The Aging Eye: Preventing and treating eye disease
/ May 28, 2015 / By / No Comments

Dear Reader,

Of your five senses, which one are you most afraid of losing? If you’re like most people, the answer is your ability to see. Despite this, many people are not conscientious about caring for their eyes and often neglect to visit an ophthalmologist for routine eye exams as they get older.

Like the rest of your body, your eyes naturally change throughout your life. These changes occur gradually and become apparent in later years, as the structures in and around your eyes become less efficient. For most people, the first sign is presbyopia, deterioration of close-up vision. Luckily, this problem can be treated with reading glasses or progressive lenses.

However, more serious age-related eye problems can cause vision loss or visual distortion that glasses can’t fix. More than 5.5 million adults ages 65 and over in the United States are considered legally blind, meaning that their vision is 20/200 or worse in their best eye, even with corrective lenses or surgery. The vast majority of them weren’t born with vision impairment. They lost their sight to diseases like macular degeneration, glaucoma, and diabetes. Over the next 30 years, the number of blind or visually impaired Americans is expected to double as the baby boomer generation ages. For most of these eye diseases, early detection and treatment can prevent or curb vision loss.

This report covers normal age-related conditions, such as presbyopia, as well as the four eye diseases that pose the greatest threats to vision after age 40: cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy. It also describes other common eye disorders, including dry eye, floaters and flashes, retinal detachment, and eyelid problems such as drooping upper or lower lids.

You’ll learn why you should have regular eye exams, especially if you have diabetes or a family history of glaucoma or age-related macular degeneration; how to recognize the risk factors and symptoms of specific eye diseases; and what steps you can take to prevent or treat them before your vision deteriorates further. You’ll learn about the latest advances in cataract surgery, as well as cutting-edge treatments for age-related macular degeneration. This report also provides specific information about what you can do to protect your eyes—; and your vision.

Sincerely,

Laura Fine, M.D.
Medical Editor

Jeffrey Heier, M.D.
Medical Editor

How the eye works

The eye is often compared to a camera, but in truth, the organ of sight is far more complex and efficient. Not only does the eye focus and snap pictures, but it also works continuously with the brain and nervous system to process ever-changing images, providing you with the visual information you need to do everything from hitting a golf ball to preparing your taxes.

Knowing eye anatomy can help you understand changes in the aging eye, whether they stem from the normal aging process or an eye disease.

Protection from without

Despite its reputation as a delicate organ, the eye is remarkably resilient and hardy, engineered by nature to last from infancy through old age. It sits in a bony, protective socket of the skull, called the orbit, and is surrounded by a cushiony layer of fibrous tissue, fat, and a set of six muscles (extraocular muscles) that regulate the eye’s movements (see Figure 1).

Figure 1: Eye anatomy: The outside view

The eyeball is surrounded by ligaments, fat, and muscles and rests in a protective, bony socket called the orbit. Six extraocular muscles control the eyeball’s movement. The cornea, a tough, transparent dome that helps focus light, and the sclera, the white portion of the eye, protect the interior of the eye.

Eyelids and eyelashes provide additional protection, acting like windshield wipers to constantly brush and blink away dust and debris that might otherwise blow into the eye. Tears from the lacrimal gland, located behind the upper lid, course over the surface of the eye and keep it lubricated, nourished, and clear of foreign matter.

The eyeball itself is sturdy. Its outer surface (approximately 1 millimeter thick) is made of tough collagen. You see it in the visible part of the eyeball as both the sclera (the white part) and the cornea, a clear, dome-like window at the front of the eye, which allows light to enter.

Less obvious protection comes from the conjunctiva—a thin, transparent membrane that lines the inner surfaces of the eyelids and the front portion of the sclera. The conjunctiva is so sensitive that when it becomes aware of a foreign body, it automatically triggers a protective reaction, such as tearing or blinking.


An exquisite structure within

The inner architecture of the eye is complex, with more than a dozen parts that work together. Some of these structures are quite familiar—others, less so.

The eye consists of two major compartments—the front (including the lens, iris, cornea, and aqueous humor) and the back (the rear two-thirds of the eyeball, including the retina and a large cavity filled with vitreous humor; see Figure 2). Structures in both are essential for sight.

In the front compartment, the iris is the pigmented section that gives your eye its color, which might be blue, green, brown, or hazel. Like an automatic camera, which adjusts the size of its aperture (opening) to the available light, the iris controls how much light enters the eye through the pupil—the black hole at the center of the iris. The involuntary muscles of the iris open to allow more light to enter the pupil in dim light, and close to make the pupil smaller in bright light. A good example of the eye’s adaptation is the change that occurs when you walk into sunlight after sitting in a dark movie theater. Even subtle alterations in light prompt a response from the eye, and the iris muscles are continually adjusting to the environment.

Just behind the pupil and iris is the lens. The purpose of the lens is to focus light rays on the retina, the thin, light-sensitive inner layer at the rear of the eye. Tiny muscles called ciliary muscles are attached to the lens and enable it to alter its shape so the eye can focus on objects at varying distances. When you look at a tree far away, the muscles cause the lens to flatten. But shift your gaze to something close, such as a computer screen, and the muscles contract, which makes the lens thicker and more curved in the middle. The ability of the lens to adjust its focus from far to near is called accommodation.

The anterior chamber is an area between the cornea and iris (see Figure 2). It’s filled with a clear liquid called aqueous humor, which nourishes the lens and removes wastes. The aqueous humor flows into this region from the posterior chamber—the area between the iris and the lens. It flows out through the trabecular meshwork and Schlemm’s canal, a circular drainage system located where the clear cornea, white sclera, and colored iris meet. In a healthy eye, this circulation constantly drains and resupplies the aqueous humor, maintaining a balance of fluid in the two chambers.

Figure 2: Eye anatomy: The inside story

Rays of light pass through the cornea, the anterior chamber, and then the lens, which focuses images. The lens is nourished by the aqueous humor, a clear, watery solution that circulates from the posterior chamber into the anterior chamber and helps maintain normal pressure. Light reaches the retina after it passes from the lens through the vitreous humor, a clear gel that fills most of the eyeball. The retina has light-sensitive cells that capture images, which are then sent to the brain via the optic nerve. At the retina’s center is the macula, a small region that provides sharp, central vision.

The ciliary body behind the iris produces the aqueous humor. It also contains the ciliary muscles, which help the lens change shape as your eye focuses.

In the back of the eyeball are other crucial structures. The retina is a mass of nerve cells and fibers where images are captured and recorded, much like the film in an old-fashioned camera. Within the retina are about 150 million rods and seven million cones—specialized cells made up of chemicals that react to different wavelengths in light. Each performs a specific function:

  • The cones perceive color and are responsible for fine detail in the center of vision. They enable you to read words on a page and recognize a familiar face from across the room. Cones are most active in bright light.

  • The rods are found throughout the retina, but are mainly in the periphery. They do not perceive color, but rather light, shadow, and motion. They are most sensitive in the dark, which explains why it is hard to detect colors and fine details in the dark.

The macula, the tiny part of the retina that gives you sharp central vision, is where most of the cones are located. But the best vision—for reading or detailed work—comes from the fovea, which is at the center of the macula. The rest of the retina delivers peripheral (side) vision, which is less sharply focused.

The choroid is sandwiched between the sclera and retina in the rear of the eye. This membrane is packed with blood vessels that carry oxygen and other nourishment to the outer part of the retina.

The images striking the retina travel to the brain via the optic nerve, which relays information about the size, shape, color, and distance of the objects you see.

Most of these structures are located near the surface of the eye. But the inner chamber of the eyeball is not empty. Rather, it is filled with vitreous humor. Unlike aqueous humor, which is a liquid, the vitreous humor is a clear, stable gel that looks like raw egg white. It gives shape to the eye and provides a pathway for light coming through the lens to the retina.


The art of seeing

Sight is not fully developed at birth; the brain and eyes have to learn to work together in the first months of life. Once sight is well developed, the eyes and brain team up to provide virtually instantaneous visual information.

Consider what happens when you walk through a parking lot and spot your car. First, you are actually seeing the light reflected off the car; some light must be present in order to see.

If the image is clear, it means that light rays thrown off the surfaces of the vehicle hit your cornea, which refracts, or bends, them inward so they pass into the eye to the lens. The lens bends the light rays further and projects them onto the retina as a flat, upside-down image.

The retina absorbs the light and turns it into electrical energy, which the optic nerve then conveys to the visual area of the brain. Data about your car—its size, shape, color, and position—are sent along the optic nerve as impulses, a sort of neurologic code that the brain deciphers. Although the image is upside down on the retina, the brain automatically turns it right side up.

Although it is possible to see with only one eye, you generally rely on binocular vision—vision with both eyes—for depth perception. You get a three-dimensional view of your vehicle because the brain interprets what your two eyes see (each with a slightly different perspective) as a single image.

If a flashy car nearby catches your attention, you instantly shift your gaze without a thought. The external muscles of the eyes are synchronized to keep the eyes aligned and to coordinate their movement.

Figure 3: Normal vision

The National Eye Institute created a series of photos to demonstrate how different eye problems affect vision. The photo above shows how a person with normal vision would see those two boys while standing 20 feet away from them. In this report, you’ll find examples of how people with cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy would see the same boys.

Photo courtesy of the National Eye Institute.


Why aging may cause problems

Just as hair turns gray and skin sags with age, the eyes, too, undergo changes as you grow older. Although many of these changes are part of normal aging, some set the stage for more serious eye problems.

As eyes age, eyelid muscles weaken, and skin becomes thinner and more flaccid. This can cause the upper lid to droop or the lower lid to sag. Eyelashes and eyebrows may lose their lushness and thin out considerably.

Tear production also drops off, and the oily film that tears provide decreases as lubricating glands in the conjunctiva and lids fail. These changes can lead to a buildup of mucus, resulting in stickiness, or make the cornea dry, causing irritation or an uncomfortable, gritty sensation in the eye.

The conjunctiva turns thinner and more fragile with age and takes on a yellowish tinge from an increase in elastic fibers. The white of your eye (the sclera) also assumes a yellow hue from a collection of lipid, or fat, deposits. Calcium may deposit in the sclera, leading to patches of grayish translucency. The exposed conjunctiva between the lids begins to degenerate, and the cornea can develop an opaque white ring around its edge.

With time, the lens hardens and loses its elasticity. This makes it more difficult to focus on near objects, a common condition called presbyopia. You might also find that your night vision grows poorer. These changes usually occur simultaneously in both eyes.

Medications that can affect your vision

Talk to your eye doctor about the medications you take for other conditions, because they circulate through your entire body and can affect your eyes. For example:

  • Amiodarone (Cordarone, Pacerone) for irregular heart rhythm can cause deposits to form on the cornea.

  • Corticosteroids such as prednisone (Deltasone) for arthritis and other ailments can lead to cataracts and increased pressure in the eye with long-term use.

  • Hydroxychloroquine (Plaquenil) for rheumatoid arthritis can cause retinal damage.

More serious age-related problems

Other changes lead to problems requiring medical intervention (see “Warning signs that warrant a doctor visit”). Following are the most common ones, all of which are covered at length later in this report. In addition, certain medications you take for other medical conditions may affect your eyes (see “Medications that can affect your vision”).

Warning signs that warrant a doctor visit

See an ophthalmologist if you experience any of the following symptoms or problems with your eyes:

  • Change in iris color

  • Crossed eyes

  • Dark spot in the center of your field of vision

  • Difficulty focusing on near or distant objects

  • Double vision

  • Dry eyes with itching or burning

  • Episodes of cloudy vision

  • Excess discharge or tearing

  • Eye pain

  • Floaters or flashes

  • Growing bump on the eyelid

  • Hazy or blurred vision

  • Halos (colored circles around lights) or glare

  • Inability to close eyelid

  • Loss of peripheral vision

  • Redness in or around the eye

  • Spots in your field of vision

  • Sudden loss of vision

  • Trouble adjusting to dark rooms

  • Unusual sensitivity to light or glare

  • Veil obstructing vision

  • Wavy or crooked appearance to straight lines

Cataract. This clouding of the lens usually develops slowly over many years. It may go unnoticed until the cloudiness blocks the central line of sight and impairs vision.

Glaucoma. Over time, the anterior chamber in each eye may become shallower in some susceptible people—those who have small eyes and are farsighted, for example. This raises the risk for blockage of the aqueous humor drainage system near the iris. The resulting fluid backup may lead to higher pressure inside the eye that damages the optic nerve, a condition known as closed-angle glaucoma. Left untreated, it can cause blindness.

Another form of glaucoma, called open-angle glaucoma, occurs when pressure builds up in the eye because of a different problem: the aqueous humor is less able to flow out through the trabecular meshwork. As in closed-angle glaucoma, the resulting buildup of pressure inside the eye can damage the optic nerve, if left untreated.

Age-related macular degeneration. The aging retina thins and may grow less sensitive because of cell loss, a reduced blood supply, or degeneration. The macula is especially prone to deterioration. Age-related macular degeneration is a serious disease that can steal a person’s central vision, making it difficult to read, write, or drive a car.

Diabetic retinopathy. Diabetes is a disease in which the body either doesn’t produce enough insulin or doesn’t use it effectively. Insulin normally moves sugar from the blood to the cells for energy. Without it, sugar builds up in the bloodstream and can damage blood vessels and organs throughout the body—including the eyes. Diabetic retinopathy occurs when blood vessels that feed the retina leak, leading to retinal swelling. When left untreated over time, this condition can lead to blindness.




Normal changes in the aging eye

Many people will never have to deal with serious eye disease. But nearly everyone will eventually experience some age-related changes in vision.

Ophthalmologists are able to treat many of the less serious problems; however, in some situations involving problems with the eyelids, tear drainage, or skin cancer, you may be referred to an oculoplastic specialist—a doctor with advanced training in plastic and reconstructive surgery of the eye and tissues around it.

Presbyopia: Ready for reading glasses?

As you age, you’ll discover that you need to hold menus and newspapers at arm’s length to read them. Presbyopia—coined from the Greek words for “old sight”—is a reduction in the eye’s ability to focus. It may start as early as the late 30s, but it typically develops in the 40s and 50s and eventually affects everyone. Presbyopia occurs when the aging lens becomes more rigid and less efficient at bending to accommodate changes in focus. An accompanying lag in the function of the ciliary muscles—the ring of muscles that helps the lens focus near or far—contributes to the difficulty in seeing small print.

Blurred close vision that leaves eyes tired and strained is an early hint that you’ve developed presbyopia. After reading or doing other detail work, you may find it hard to see distant objects clearly. The problem may be more pronounced when you try to read in poor light, or in the evening when you are tired. The condition occurs regardless of whether you are nearsighted, farsighted, or astigmatic. However, presbyopia often affects farsighted people at a younger age than those who are myopic (nearsighted). If you’re nearsighted (see Figure 4), you may be able to overcome presbyopia at first by taking off your glasses to read. Eventually, as your presbyopia worsens and the lens of your eye becomes stiffer, you may need new corrective lenses.

Figure 4: Faulty optics: When your vision isn’t perfect

When the eye sees normally, light focuses directly on the retina, producing a clear image. But in some people, the optics are faulty, and images appear blurred because the eye focuses the image either in front of or behind the retina. These problems are not eye diseases, but common conditions known as refractive errors of the eye. Although laser surgery procedures such as LASIK have become increasingly popular as a way to correct refractive errors, such techniques are usually appropriate only for people younger than 50. For that reason, refractive errors in older adults are most often corrected with eyeglasses and contact lenses.

Myopia (nearsightedness). A nearsighted person has difficulty seeing objects at a distance because the light rays converge and focus before reaching the retina. The cause is usually an elongated eyeball (which requires light rays to travel farther than they would in a normal eye) or a lens or cornea that is too strong, bending the light rays so they focus before reaching the retina.

Hyperopia (farsightedness). A farsighted person sees objects better at a distance than up close. In this case, the eyeball is usually too short, and light rays reach the retina before they are focused. Hyperopia can also be caused by weaknesses in the refractive power of the lens and cornea. You may not notice farsightedness for years, but because the eye’s corrective ability diminishes with age, you will probably need glasses by midlife.

Astigmatism. A person with astigmatism has irregularities in the curvature of the cornea’s surface that cause distorted vision. Light rays do not meet at a single point. For some people, vertical lines appear blurry; for others, horizontal or diagonal lines look out of focus. Astigmatism develops early and is usually well established after the first few years of life. It often occurs together with nearsightedness or farsightedness.

The most common remedy for presbyopia is reading glasses. Prescription glasses provide the greatest precision, but many drugstores and supermarkets carry inexpensive reading glasses that may work well for you. Have your ophthalmologist perform an eye exam before you purchase a pair of reading glasses, so you’ll know which strength to buy.

If you already wear glasses, you might consider bifocals, trifocals, or progressive lenses, which combine several levels of adjustment to correct both distance and close-up vision problems. Some people use two pairs of glasses—one for distance and one for close work.

If you wear contact lenses, multifocal contact lenses that combine several levels of adjustment (bifocal, trifocal, or progressive lenses) are also available. Or you can get one prescription contact lens that corrects the vision in one eye for reading, and another lens that corrects for distance—a technique called monovision (see “Surgical monovision”).

Whichever type of lens you choose, you may need to update your prescription often, because presbyopia becomes worse with age. It should finally stabilize between ages 60 and 65.

Surgical monovision. Another option for people ages 40 to 60 who have presbyopia but otherwise healthy eyes is to surgically correct one eye for close-up vision, leaving the other for distance vision. Monovision doesn’t fix the stiffened lenses that cause presbyopia, but it can eliminate the need for bifocals or multiple sets of glasses, and it may even enable you to read without glasses. However, one eye will be slightly sharper than the other at specific distances, which could affect your depth perception.

Doctors use various procedures to make the correction. Laser surgery techniques include laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and laser thermal keratoplasty (LTK), each of which reshapes the cornea or the area around it to provide correction. (The technique used depends on your particular circumstances.) If you choose laser surgery and you still have good distance vision, the surgeon will correct one eye so you can see up close, leaving the other eye with your natural ability to see far. If you’re both myopic and presbyopic, the doctor can correct your nondominant eye for near vision and your dominant eye for distance. It may take several surgeries to get the desired result, and the results may not last.

Another technique used for monovision is conductive keratoplasty (CK). This method is similar to laser surgery, but instead of a laser, it uses short bursts of radio waves to shrink and reshape the cornea. One limitation is that it can take a few months before you see the full benefits. There is a slight risk that CK may also cause astigmatism.

Monovision isn’t for everyone. It is vital that your eyes be healthy and free from other eye defects, such as cataracts, glaucoma, or corneal problems. Some people find it too difficult to adjust to different focusing abilities in each eye. If you’re considering this surgery, the FDA advises that you try monovision with contact lenses first, to see whether you can adjust.

Refractive lens exchange (clear lens extraction). The artificial lenses used for cataract surgery today are superior to earlier ones, providing another surgical option for people who are nearsighted. Replacing a still-healthy natural lens—one that hasn’t been clouded by a cataract—is controversial, but some ophthalmologists will replace the natural lenses in middle-aged or older people who have refractive vision errors like presbyopia and hyperopia, but who aren’t candidates for LASIK corrective surgery.

Keep two things in mind before undergoing refractive lens exchange surgery for presbyopia. First, it is not approved by the FDA and will not be covered by insurance unless you have cataracts. (The cost can be as high as $5,000 for each eye.) Second, many ophthalmologists are reluctant to perform this procedure in people without cataracts because of risks like retinal detachment and vision loss, and the lack of information about long-term safety and effectiveness.

Phakic intraocular lenses. These surgically implanted lenses may be an alternative to LASIK for correcting nearsightedness. In contrast to cataract surgery, which replaces your natural lens, phakic lenses are placed either between the cornea and the iris or just behind the iris, without removing your lens. The phakic lens bends light rays to focus them more accurately on your retina. Two FDA-approved phakic lenses are available—Verisyse and Visian Implantable Collamer Lens. However, the FDA lists a number of risks associated with phakic lenses, including possible vision loss or vision problems such as halos, glare, or double vision. The lenses may also increase your risk of developing glaucoma or cataracts.


Double vision

When your vision is working correctly, you should see images clearly. But sometimes, you might see not one, but two of the same image. This is called double vision, or diplopia.

Double vision can occur with one eye open (monocular diplopia), usually because of a focusing problem with the eye. More often, you’ll see double with both eyes open (binocular diplopia), which occurs when the eyes are misaligned.

Causes of double vision include

  • an aneurysm, tumor, or another growth that presses on a nerve

  • astigmatism or other refractive error

  • cataracts

  • Graves’ disease

  • multiple sclerosis

  • myasthenia gravis (an autoimmune disease that affects the muscles)

  • paralysis of nerves controlling muscles that move the eye

  • a problem with the shape of the cornea

  • stroke

  • swelling or infection of the eye.

Any double vision warrants a visit to an ophthalmologist for testing. The ophthalmologist will help determine whether the double vision is a byproduct of an underlying condition, such as a thyroid problem, in which case you will also need to have that condition treated. To help alleviate the double vision, treatment options depend on the nature of the problem and might include corrective lenses, prism glasses (which bend the light that shines through them), cataract surgery, surgery to fix the eye muscles, or Botox injections.


Eyelid problems

Age, certain diseases, and some cosmetic treatments can affect the muscles and skin of the upper and lower eyelids. Often the problem affects your appearance and nothing more, but in other cases it may interfere with vision or cause eye irritation, leading to watery eyes and other difficulties.

Blepharitis. Blepharitis is inflammation of the eyelids. It can be caused by a problem with the oil glands near the base of the eyelids, a bacterial infection, or skin conditions like rosacea or seborrheic dermatitis (dandruff of the scalp and eyebrows). Though blepharitis usually doesn’t affect your sight, it can make your eyelids red, itchy, and swollen and leave your eyes red and watery. Your ophthalmologist might recommend treatments like artificial tears or steroid eye drops to relieve discomfort from blepharitis. You’ll also get treated for the cause of the problem, for example, with anti-dandruff shampoo or antibiotics. It also helps to regularly clean your eyelids with a warm washcloth.

Ptosis. Over time, the upper eyelids may start to sag as the muscles that support them lose their strength. Eye injury, nervous system problems, and disease (such as diabetes or myasthenia gravis) can also bring on this condition. Botox injections to eliminate wrinkles at the brow and forehead may also cause drooping, which can last as long as three months.

Although upper eyelid drooping is often a cosmetic concern, it can interfere with sight if the lid is so lax that it covers or partially covers the pupil. Before trying any treatment, you will need a medical exam to identify the cause. If a disease caused your ptosis, the drooping usually improves when the disease is treated. If the problem is caused by Botox injections, it’s best to wait until the injections wear off, which should happen in about three to four months.

If a droopy eyelid is unattractive or interferes with your vision and is not caused by a treatable disease, you may want to consider surgical repair. The ptosis repair procedure removes excess tissue and lifts the lid. It can be performed under local or general anesthesia on an outpatient basis. Many health insurers will cover this operation only if the ptosis affects your vision. Your ophthalmologist or oculoplastic specialist can determine whether this is the case.

Blepharochalasis. When the skin loses elasticity and sags, it creates new skin folds that can actually droop over the lashes and block the upper field of sight by covering the pupil. In blepharochalasis, just the skin of the lid begins to droop, not the entire lid as in ptosis. This condition may be surgically corrected with a procedure called blepharoplasty. As with ptosis, most health insurers will pay for this repair only if the condition interferes with vision.

Ectropion. This condition occurs when the muscles of the lower lid weaken, making the lid sag and turn outward, away from the eyeball. As a result, the upper and lower lids no longer meet when the eye is closed, and the eye may tear excessively. The constantly exposed cornea and conjunctiva may become red and irritated. In mild cases, no treatment is needed. You can use over-the-counter artificial tears and a plastic eye shield at night to help retain moisture. If the symptoms or appearance are more bothersome, surgery can tighten the lower eyelid and surrounding muscles so that the eyelid rests more closely against the eyeball. After the surgery, you may need to wear an eye patch and apply antibiotic ointment for a few days.

Entropion. In this condition the lower lid rolls in, toward the eye. Because the lashes constantly rub against the cornea, entropion may produce irritation, a feeling of something in the eye, tearing, and blurring. Sometimes, in mild cases, it helps to tape the lower lid to the cheek every night so the edge of the lid and the lashes are in the proper position. Ask your doctor if this approach might work for you and find out how to do it properly. A surgeon can also correct this disorder with a relatively simple procedure that removes a piece of your lower eyelid to tighten the skin and underlying muscles of the lid.

Skin cancer. It’s a good idea to periodically check your eyelids for any unusual growths that change color or shape. Alert your ophthalmologist if you notice anything unusual. Your doctor can examine the growth and decide whether it should be biopsied. If it is cancerous, an oculoplastic specialist will remove it and reconstruct the eyelid as necessary.


Dry eye syndrome

As people age, their tear production declines, producing irritation, burning, or a slightly painful, scratchy feeling in the eye. Sometimes mucus accumulates, causing a sticky sensation. You may become sensitive to light, have trouble wearing contact lenses, or even find it difficult to cry. When the problem is severe, it may feel like you have sand in your eyes. This syndrome is called dry eye.

Symptoms of dry eye syndrome

  • Persistent sensation of grittiness in the eyes

  • Difficulty wearing contact lenses

  • Inability to shed tears

  • Burning sensation in low humidity or polluted air

About six million women and three million men in the United States have moderate to severe dry eye syndrome. An estimated 20 million to 30 million more have milder symptoms of this condition. Dry eye syndrome usually starts in middle age, and it affects 5% to 30% of people ages 50 and older.

Dry eye is more common in people who have

  • allergies

  • blepharitis (inflammation of the eyelid)

  • lupus

  • rheumatoid arthritis

  • Sjögren’s syndrome (an immune system disorder)

  • skin disorders like rosacea or seborrheic dermatitis.

An ophthalmologist can diagnose dry eye syndrome with a slit lamp and can test the amount of tear production. If the problem is caused by a reduction in natural tear production, artificial tears may help. When the condition is mild, it may not require treatment. For moderate to severe cases, treatment usually involves some type of topical medication (nonprescription artificial tears or ointments; see Table 1) or a prescription medication, such as topical cyclosporine (Restasis). Some doctors can provide you with tears made from your own serum, which is the clear liquid separated from clotted blood. Although dry eye may be sporadic, longtime sufferers often need to use these drugs regularly.

Your doctor might also prescribe an eye insert such as hydroxypropyl cellulose (Lacrisert), which is placed between your lower eyelid and eyeball. As the insert dissolves, it slowly releases the same substance found in artificial tear eye drops to keep your eyes moist.

To minimize evaporation of tears, avoid exposure to dust, pollen, cigarette smoke, and other pollutants. Also, stay out of the wind and away from hair dryers and air conditioner currents. Humidifiers may help by adding moisture to indoor air.

What you eat may also help keep your eyes moist. One study found that women who ate plenty of omega-3 fatty acids (a healthy fat found in tuna, salmon, and other fatty fish, as well as in flaxseed) were less likely to develop dry eye syndrome than women who rarely ate such fats. Tuna in particular seemed to be the most beneficial.

In severe cases, an ophthalmologist may need to insert plugs into the tear drainage ducts. The plugs prevent your natural tears from draining out of the opening in the inner corner of the eyelid. Alternately, your doctor may prescribe special soft contact lenses that help hold in moisture. You may also be advised to wear goggles at night to retain moisture, especially if your eye does not fully close while you sleep.

Table 1: Over-the-counter options for dry eye syndrome

Products known as artificial tears or ophthalmic lubricants relieve dryness and discomfort by adding moisture and lubrication to the eyes. If you need to use these products more than four times a day, you should use single-dispense vials, which many brands offer. Multiple-use containers generally include preservatives, which may cause eye irritation if the drops are used frequently. The thicker gel formulations and ointments are best used just before bedtime, as they tend to blur vision during the day.

Active ingredient

Brand names

methylcellulose

GenTeal, Just Tears, Nature’s Tears, Refresh, TheraTears, Ultra Tears

polyethylene glycol

Advanced Eye Relief, Blink Tears, Oasis Tears, Soothe, Systane, Viva Drops

polyvinyl alcohol

Akorn Artificial Tears, Clear Eyes Artificial Tears, Freshkote, Murine Tears, Nutratear, Refresh Classic, Tears Again

combinations of active ingredients

Hylo, Hypotears, Refresh Optive, Similasan, Soothe XP, Tears Naturale, Tears Renewed

Watery eyes

Although some people develop dry eyes as they grow older, others have the opposite problem—watery eyes. This may seem counterintuitive, but the problem often develops because of dry eye syndrome. Dry eyes are uncomfortable, which causes the eyes to reflexively produce more tears.

Symptoms of watery eyes

  • Persistent tearing

  • Redness

  • Discomfort

  • or sinuses

Watery eyes also can result from tear drainage problems. Normally tears drain from the surface of your eyes, flow under the eyelids, and pass down into the nasal passages. But if this drainage system gets blocked, tears can build up in the eyes until they spill over the lids. An eyelid problem or infection also can lead to watery eyes.

Your doctor may analyze tear samples to see if an infection is to blame, or test your tear production. Another test involves irrigating the tear drainage system to check for possible blockages.

Treatment for watery eyes depends on the cause. If dry eye syndrome is causing excessive tearing, the treatment is the same as for dry eyes (see previous section). When an infection is responsible, your doctor will most likely prescribe antibiotics. Surgery may help repair an obstruction in the drainage system.



Conjunctivitis

Conjunctivitis, also known as “pink eye,” isn’t just for children. This inflammation or infection of the conjunctiva—the clear layer lining the inner surface of the eyelid and the white of the eye—can occur at any age.

Signs that you might have conjunctivitis include

  • itching or burning in the eyes

  • discharge from one or both eyes

  • a pinkish color to the whites of the eyes

  • tearing and greater light sensitivity.

Four different types of conjunctivitis exist, and each type is treated slightly differently:

Allergic conjunctivitis is caused by an allergy to an airborne substance (such as seasonal pollen) or a foreign body in the eye (such as a contact lens). The best way to prevent it is to avoid the offending substance. You can treat mild cases with artificial tears. Relieve more severe allergic conjunctivitis with antihistamines, NSAIDs, or steroid eye drops.

Bacterial conjunctivitis occurs from an infection with staphylococcal or streptococcal bacteria, and it is contagious. This type of conjunctivitis is treated with antibiotic drops or ointment.

Chemical conjunctivitis occurs after you’ve been exposed to an irritant, such as air pollution or chlorine in a swimming pool. You can treat it by flushing the eye with a saltwater solution (saline), then applying steroid drops.

Viral conjunctivitis is caused by the same types of viruses responsible for upper respiratory infections like the common cold. It should go away once the illness runs its course. To increase your comfort in the meantime, try artificial tears and cool compresses.


Floaters

Older people often notice occasional spots or opaque flecks drifting across their line of vision, particularly when they look at a page of a book, a computer screen, or a solid, light background. These symptoms may be most noticeable when you are tired. These floaters are tiny clusters of cells or gel in the vitreous cavity, where the clear, jelly-like substance called vitreous humor fills your eyeball. What you actually see is the shadow these little clumps cast on the retina. In some cases, the vitreous gel may detach from the retina and suddenly cause more floaters—a condition known as posterior vitreous detachment.

About 25% of people have these vitreous detachments and floaters by their 60s, and 65% have them by their 80s. Floaters also appear more often in people who are nearsighted, have had cataract surgery, or had recent injury to the head or eyes. These phenomena are usually nothing more than an annoyance and often dissipate or become less bothersome on their own. However, if they occur suddenly or noticeably increase, consult an ophthalmologist. Certain eye diseases or injuries can cause floaters. Occasionally, floaters can also be small drops of blood from a torn retinal vessel. Less commonly, new floaters are the sign of a retinal tear, which should be evaluated.

Once floaters have been checked and declared harmless, one of three things may happen. A floater may disappear as it breaks apart or settles; it may become less noticeable with time as your brain pays less attention to it; or it may persist to the point where it becomes bothersome. Floaters can be removed, but the risk of surgery is greater than that of the floater itself. If floaters interfere with your central vision, moving the eye up and down or left and right may shift them out of your line of sight and provide temporary relief.


Flashes

Seeing shooting stars—a phenomenon called photopsia—is relatively common as people age. Solitary flashes appear as sparks or minuscule strands of light, almost like streaks of lightning across the sky. They occur when the vitreous gel bumps, rubs, or tugs against the retina. Flashes are generally harmless and require no treatment, but in rare cases, they may warn of more severe retinal complications (see “When flashes signal an emergency: Retinal tear or detachment”). If their appearance is sudden or accompanied by a shower of floaters or a loss of peripheral vision, call your ophthalmologist at once. Photopsia differs from the flashing or zigzag lights that may precede migraine headaches.


When flashes signal an emergency: Retinal tear or detachment

Occasionally, floaters and flashes can be a sign of something far more serious: a retinal tear or retinal detachment. In a retinal tear, the vitreous gel pulls on the retina with enough force to tear the retina. Fluid from inside the eye may enter through this tear and separate the retina from the underlying tissues that nourish it. Separation of the retina from the back of the eye is called a retinal detachment.

Symptoms of retinal detachment

Contact your ophthalmologist immediately—or failing that, go to the emergency department of your local hospital—if you notice any of these early warning symptoms of retinal detachment:

  • Flashing lights

  • New or increased floaters

  • Gradual shading of vision from one side (like a curtain being drawn)

  • Quick deterioration of sharp, central vision (this occurs when the macula detaches)

People who are middle-aged and older are most likely to experience retinal detachment. Nearsightedness increases the chances for detachment, as do cataract removal surgery and eye injuries.

Retinal detachment is a serious condition that can lead to permanent vision loss. If you suspect that your retina is detaching, contact your ophthalmologist immediately. If you cannot reach your own doctor, go to an emergency room for evaluation. When a retinal tear is caught early, treatment may prevent detachment. Left untreated, the condition may worsen until the retina separates completely from the inner wall of the eye, remaining connected only at the optic nerve in the back of the eye and the ciliary body in the front of the eye. In the worst cases, retinal detachment causes blindness.

Because the underlying disorder that causes retinal tears may occur in both eyes, your ophthalmologist will want to examine both eyes thoroughly. Your other eye may also have retinal deterioration or other problems that require treatment.

A dilated eye exam using an indirect ophthalmoscope (a device that is mounted on special headgear) enables the doctor to determine the extent of the detachment and the location of any holes or tears. This can help the doctor determine the best way to treat the problem. Some retinal tears don’t require treatment, especially if they are old. But most cases of retinal detachment call for surgery to reposition the separated retina against the back wall of the eye.

Laser photocoagulation. In this procedure, which is done on an outpatient basis with topical anesthesia, the doctor uses pinpoints of laser light to create tiny burns around any small holes or tears in the retina. The resulting scar tissue forms a barrier that essentially welds the retina to the back wall of the eye so that it is less likely to detach (see Figure 5).

Figure 5: Laser photocoagulation

In this procedure, which is usually done in an office, the ophthal-mologist uses a laser to make a series of tiny burns around the retinal tear. This creates a barrier of scar tissue that stops the tear from getting worse.

Cryopexy. An ophthalmologist may also repair tears that have not yet caused detachment by applying a freezing treatment called cryopexy. Like laser photocoagulation, this approach functions as spot welding for the retina, reducing the likelihood that the tear might lead to a detachment. This procedure is performed on an outpatient basis using local anesthesia. It may be used when the location of a tear makes laser surgery too difficult to perform.

Pneumatic retinopexy. This approach is frequently used as the initial treatment for repairing a detached retina, because it can be done on an outpatient basis and it leads to the quickest vision recovery. Whether or not it will work for you depends on the location of your retinal tear (or tears) and the characteristics of the retinal detachment.

For this procedure, you receive local anesthesia to numb the eye. The ophthalmologist first uses cryopexy (or, less frequently, laser photocoagulation) to create a barrier with scar tissue. The ophthalmologist then injects a gas bubble into the vitreous cavity. As the gas bubble expands over the next few days, you are positioned in a way that allows the gas to hold the retina in place, enabling the cryopexy to seal off any holes. This leads to reattachment. Eventually the gas bubble dissipates, and fluid in the eye takes its place.

The most challenging aspect of this procedure may be the recovery. To ensure that the retina reattaches properly, and depending on the location of the retinal tears, you may have to spend a significant amount of time each day in a face-down position to keep the bubble in the correct position. (If necessary, you can rent special equipment to help you achieve the right position.) Until the gas bubble disappears, you should also position pillows in your bed to prevent you from lying on your back. Your physician can provide more specific advice.

Scleral buckling. This procedure, which is done in an operating room under local or general anesthesia, drains the fluid so the retina falls back against the choroid. The hole is sealed, and then a silicone buckle is sutured around the outside of the eyeball to slightly indent the sclera (the white outer layer of the eyeball) so that it makes better contact with the retina. In addition to this procedure, you will undergo cryopexy or laser therapy, and a gas bubble may be injected to keep the retina in place.

Vitrectomy. This surgery is usually performed under local anesthesia. The surgeon removes the vitreous humor that might be causing traction or tugging on the retina and performs cryopexy or laser treatment. Then the vitreous humor is replaced with a saline solution or gas bubble, which dissipates on its own.



Safeguarding your sight

Although aging puts people at greater risk for serious eye diseases, vision loss does not have to go hand in hand with growing older. Practical, preventive measures can help protect against such devastating eye changes.

An estimated 40% to 50% of all blindness can be avoided or treated with regular visits to a vision specialist. Eye exams are the cornerstone of visual health as people age. (For guidelines on how often to be examined, see Table 2.) Individuals who have a family history of eye disease or other risk factors should have more frequent exams. Don’t wait until your vision deteriorates to have an eye exam. One eye can often compensate for the other while an eye condition progresses. Frequently, only an exam can detect eye disease in its earliest stages.

Beyond regular eye exams, there are also practical steps that everyone should take to help prevent damage to the eyes. These include adapting your lifestyle and protecting the eye from dangerous exposures, both internal and external.

Table 2: How often do you need routine eye exams?

Otherwise healthy people with no risk factors

Younger than 40

Get a vision screening once every three years, but see an ophthalmologist if you are having problems

Ages 40 to 64

Get a complete eye exam from an ophthalmologist once every two to four years to monitor for glaucoma and a vision screening to correct for presbyopia

Ages 65 and older

Get a complete eye exam every one to two years

People at high risk for eye diseases

Type 1 diabetes

Get a complete eye exam five years after diagnosis, then once a year

Type 2 diabetes

At the time of diagnosis, then once a year

At risk for glaucoma, ages 40 to 54

Every one to three years

At risk for glaucoma, ages 55 to 64

Every one to two years

At risk for glaucoma, ages 65 or older

Every six to 12 months

Special considerations

  • People with certain eye conditions or risk factors for those conditions need to have eye examinations more frequently.

  • People with certain illnesses, or those taking certain medications, such as amiodarone (Cordarone), ethambutol (Myambutol), hydroxychloroquine (Plaquenil), prednisone, or tamoxifen, may need more frequent exams; ask your doctor for guidance.

The eye examination

Regular, comprehensive eye exams are the best way to detect eye disease early, when treatment is most effective. A thorough eye exam involves a series of evaluations—some done in the dark, some in the light, and some with special instruments. People who feel their eyes are too sensitive or who fear an eye exam should be assured it is not painful.

Because some eye disorders are inherited and others develop after an illness, the doctor will ask about your family and personal health history. Diabetes, for example, can affect vision and always deserves careful attention (see “Diabetic retinopathy”).

Your eye professionals

If you’ve ever been confused about whether you need to see an ophthalmologist, optometrist, or optician, you’re not alone. Although the names of these specialists sound similar, each plays a distinct role in eye care. Because the training and experience of each specialist varies, it is important to seek the services of the appropriate professional for your eye care needs.

Ophthalmologist. An ophthalmologist is a physician—either a doctor of medicine (M.D.) or doctor of osteopathy (D.O.)—who specializes in medical and surgical care of the eyes and visual system, as well as in the prevention of eye disease. Licensed ophthalmologists must complete four or more years of medical school, one year of internship, and three or more years of specialized medical, surgical, and refractive training. Ophthalmologists are qualified to diagnose and treat (medically and surgically) diseases, disorders, and injuries of the eyes and visual system. In addition, they can provide more basic eye care, including prescribing eyeglasses and contact lenses.

Oculoplastic specialist. This is an ophthalmologist who has received advanced training in plastic and reconstructive surgery of the eye and surrounding structures. Oculoplastic specialists are often consulted for problems with the eyelids, tear drainage, and skin cancer around the eyes.

Optometrist. An optometrist, or doctor of optometry, is a health service provider who deals with vision problems. Optometrists must complete a four-year course at an
accredited college of optometry, but they do not attend medical school and are not trained to perform surgery.

They are licensed by the state to examine the eyes, determine the presence of vision problems (including eye diseases), and prescribe eyeglasses and contact lenses. In many states, optometrists are permitted to treat certain eye conditions with medications. Normally, if an optometrist diagnoses a serious eye disorder in a patient, he or she will refer that person to an ophthalmologist.

Optician. An optician is a technician who makes and fits eyeglasses, contact lenses, or other optical devices that have been prescribed by an ophthalmologist or optometrist.


Testing your vision

The familiar set of rows of letters and numbers that diminish in size is called the Snellen chart. A doctor or technician uses this chart to test the sharpness of your central vision, known as visual acuity. Think of central vision as your eye’s “vital sign,” much like blood pressure and heart rate are the heart’s vital signs. If you wear corrective lenses, the doctor tests your vision while you wear your glasses or contact lenses and also looks at your glasses through a device called a lensometer to determine their exact prescription.

Your exam score indicates how well you see compared with someone whose vision is normal. For instance, if you have 20/20 vision—considered the standard for normal—you can see at a distance of 20 feet what another individual with normal vision sees at 20 feet. However, if your vision is 20/40, you see at a distance of 20 feet what a person with normal vision would be able to see at 40 feet; in other words, you need to stand closer to the object to see it as clearly. In general, the higher the second number, the worse your vision.

If the test indicates a need for corrective lenses or a prescription adjustment, the doctor measures the eye’s refraction, or focusing accuracy, using instruments that contain a combination of corrective lenses. To confirm that reading, you will be asked to look through a variety of lenses to ascertain which one gives you the best sight.

The doctor will also evaluate your peripheral vision. Typically you’ll be asked to cover one eye and fix the other eye on a point straight ahead. The doctor will shift an object, such as a pen, back and forth at the outer edges of your visual field and ask you to note when you see it moving.

In certain circumstances, your color vision may also be measured with special color pictures. In addition, depth perception can be determined with a series of three-dimensional images. This is especially important if anyone in your family has had strabismus (eye muscle imbalance).


Examining the external eye

The doctor examines the outer eye—the lids, lashes, and orbit—and looks for signs of any underlying problems, such as infections, sties, cysts, tumors, or lid muscle weakness. The doctor then checks your eyeball’s appearance (including the sclera and conjunctiva) and notes whether the pupil reacts normally to light.

Checking the coordination of the six muscles in each eye is an important part of the exam. Tests vary, but the goal is to ensure that your eyes function properly together.


Examining the internal eye

Using a slit lamp, a diagnostic tool with a powerful microscope and a narrow slit of light, the doctor can explore different levels of the eye’s transparent tissue and assess the inner workings of the eye. As you keep your head steady on a chin rest, beams of light are projected onto and into your eye. The instrument’s use of narrow light beams and high magnification provides a cross-sectional picture of eye tissue. This gives the doctor a close-up view of the cornea, anterior chamber, lens, vitreous humor, and retina. The doctor will check for many things, including degeneration or the presence of foreign particles in the cornea, inflammation within the anterior chamber, cataract, floaters, and tumors or abnormal blood vessels in the iris.

Testing pupil dilation. The doctor applies special eye drops to dilate your pupils, allowing a better examination of the eye’s interior. The drops take time to wear off, so people often experience light sensitivity and difficulty focusing on close tasks for several hours afterward. Be aware that it is often difficult to drive while your eyes are dilated. Some ophthalmologists offer drops to reverse the dilation of your eyes after the exam. These drops typically reduce the time it takes to recover from the dilation and help your vision return to normal more quickly.

Measuring eye pressure (tonometry). This painless test to measure eye pressure can detect possible signs of glaucoma and is also used to monitor glaucoma treatment. The simplest version, known as air-puff or noncontact tonometry, uses an instrument called a tonometer that emits a puff of air to determine what force it takes to flatten the cornea. Anyone at risk for glaucoma, including those who are over age 40 or who have a borderline result with the air-puff test, should be given a more accurate test, known as applanation tonometry. After the eye is numbed with anesthetic drops, the doctor gently touches the cornea with an instrument to measure the eye’s internal pressure.

Viewing the retina and optic nerve. Finally, the doctor will use a hand-held ophthalmoscope or focusing lenses with a light source (mounted on the doctor’s head or on the slit lamp) to look more deeply into your eye to evaluate the clarity of the lens and vitreous humor and the health of the retina, macula, optic nerve, and their blood vessels. In special circumstances, the doctor will use different lenses to view the far periphery of the retina.



Practical steps

You can take other steps on your own to protect and preserve your vision. The eyes are priceless and deserve to be treated with care and respect. Following are some of the most important steps you can take to help ward off problems.

Don’t smoke. The chemicals in cigarette smoke travel through the network of tiny blood vessels that supply your macula. Eventually, those chemicals can damage the blood vessels and lead to age-related macular degeneration. Smoking has also been linked to an increased risk for cataracts.

Wear sunglasses and a hat. For tips on choosing sunglasses, see “Investing in the right sunglasses”. As for the hat, it should have a three-inch brim to protect your eyes from the sun’s ultraviolet (UV) radiation, which has been linked to eye damage—particularly cataracts and age-related macular degeneration.

Investing in the right sunglasses

The easiest way to protect your eyes from the sun’s hazardous radiation is to wear sunglasses, not only in the summer months, but year-round. Ultraviolet (UV) light can damage the iris, retina, lens, and cornea, leading to permanent vision loss. It’s a good idea to request UV protection (an invisible coating) on all of your prescription glasses.

UV light has three wavelengths:

  • UVA is long, looks almost blue in the visible spectrum, and is responsible for skin tanning and aging.

  • UVB is shorter, more active, and linked to sunburn and skin cancer. A large portion of UVB light is absorbed by the atmosphere’s ozone layer.

  • UVC is short and completely absorbed by the ozone layer.

Sunglasses are labeled according to guidelines for UV protection established by the American National Standards Institute (ANSI). There are three categories:

  • Cosmetic. Lightly tinted lenses, good for daily wear. Block 70% of UVB rays, 20% of UVA, and 60% of visible light.

  • General purpose. Medium to dark lenses, fine for most outdoor recreation. Block 95% of UVB, 60% of UVA, and 60% to 90% of visible light. Most sunglasses fall into this category.

  • Special purpose. Extremely dark lenses with UV blockers, recommended for places with very bright conditions, such as beaches and ski slopes. Block 99% of UVB, 60% of UVA, and 97% of visible light.

Just because a lens is expensive or appears darker doesn’t mean that its ability to block out UV radiation is any greater than that of a cheaper or lighter lens. Look for the ANSI label. Even inexpensive sunglasses can be effective.

There is some evidence that blue light from the sun may contribute to the development of age-related macular degeneration. Lenses with a red, amber, or orange tint may provide better protection against this light. You may find less distortion, however, with gray or green lenses.

If you aren’t sure what kind of sunglasses to buy or think you may be at high risk for eye disease, consult an eye care professional.

Eat a nutritious diet, with plenty of fruits and vegetables. Just as sunglasses and a hat protect your eyes from the outside, these foods can protect your vision from the inside, helping to ward off certain eye diseases. For example, studies show that people who eat the most foods rich in the antioxidants lutein and zeaxanthin (such as spinach and other dark green vegetables) are less likely to develop cataracts and age-related macular degeneration. These nutrients filter out harmful blue wavelengths of light, protecting your eye cells from damage. It’s also a good idea to minimize saturated fats and hydrogenated oils, which contribute to blood vessel damage and can diminish blood flow to your eyes.

Wear safety glasses or goggles. Thousands of eye injuries occur every day, and 90% of them would have been preventable with the use of appropriate safety eyewear. Put on protective goggles or safety glasses whenever you work with power tools, use cleaning supplies or other chemicals, or play sports. If you do get chemicals in your eyes, immediately flush the eye with water in the sink or shower for 15 minutes. Do not bandage it. Seek medical care immediately.

Common eye myths dispelled

Myth: Doing eye exercises will delay the need for glasses.

Fact: Eye exercises will not improve or preserve vision or reduce the need for glasses. Your vision depends on many factors, including the shape of your eye and the health of the eye tissues, none of which can be significantly altered with eye exercises.

Myth: Reading in dim light will worsen your vision.

Fact: Dim lighting will not adversely affect your eyesight. However, it will tire your eyes out more quickly. The best way to position a reading light is to have it shine directly onto the page, not over your shoulder. A light that shines over your shoulder will cause a glare, making it more difficult to see the reading material. A desk lamp with an opaque shade pointing directly at the reading material is the best possible arrangement.

Myth: Carrots are the best food for the eyes.

Fact: Carrots, which contain vitamin A, are indeed good for the eyes. But fresh fruits and dark green leafy vegetables, which contain more antioxidant vitamins such as C and E, are even better. Antioxidant vitamins may help protect the eyes against cataracts and age-related macular degeneration. Just don’t expect them to prevent or correct basic vision problems such as nearsightedness or farsightedness.

Myth: It’s best not to wear glasses all the time. Taking a break from glasses or contact lenses allows your eyes to rest.

Fact: If you need glasses for distance or reading, use them. Attempting to read without reading glasses will simply strain your eyes and tire them out. Using your glasses won’t worsen your vision or lead to eye disease.

Myth: Staring at a computer screen all day is bad for the eyes.

Fact: Using a computer will not damage your eyes. However, staring at a computer screen all day will contribute to eyestrain or tired eyes. Adjust lighting so that it does not create a glare or harsh reflection on the screen. When you work on a computer or do other close work such as reading or sewing, it’s a good idea to rest your eyes briefly every 20 minutes to lessen eye fatigue. People who stare at a computer screen for long periods tend not to blink as often as usual, which can cause the eyes to feel dry and uncomfortable. Make a conscious effort to blink regularly so that your eyes stay well lubricated.

Learn about the aging eye. You should know how to recognize risks and symptoms, so you’re alert to the warning signs of vision problems and can see a doctor right away, before a condition causes further damage. If you have diabetes, controlling your blood sugar can delay both the start and progression of retinopathy.

Limit your screen time. Spending many hours in front of a television or computer screen or working in poor light does not cause harmful medical conditions (see “Common eye myths dispelled”), but it can tire the eyes. Follow the 20-20 rule: for every 20 minutes you spend looking at your computer screen, look away for at least 20 seconds to give your eyes a rest.



Cataracts

Cataracts affect more than 24 million Americans. A cataract is a clouding of the normally clear lens of the eye. The term was apparently coined because looking through a clouded lens is like looking through a cataract, or large waterfall. It takes years for the lens to become foggy, but the opacity can eventually cause a disabling loss of vision, either by distorting light rays or keeping them from reaching the retina at all. People can develop cataracts in their 40s and 50s, but most of these are small. It is after age 60 that most cataracts start to cause vision problems.

Despite surgical advances, the lack of access to health care in developing countries makes cataracts the leading preventable cause of blindness in the world today.

Symptoms of cataracts

Any of these symptoms in one or both eyes may be a sign of cataracts:

  • Blurry or dim vision

  • Glare from bright lights

  • Double vision

  • images

  • nearsightedness

  • Declining night vision

What causes cataracts?

Contrary to what some people believe, cataracts are not caused by a film blanketing the eye; nor are they related to overuse of the eyes. They do not spread from one eye to the other—although the condition may develop in both eyes.

Aging and accompanying changes in the chemical composition of the lens are the most common causes. Many cataracts develop as an exaggeration of a normal aging process known as sclerosis or hardening. The lens becomes less resilient, less transparent, and often thicker. Fibers in the lens compress, and the lens stiffens. Clarity fades as proteins clump together, creating tiny specks or wheel-like spokes in the outer edges of the lens. In later stages, the milkiness becomes denser and occurs in the center, making it difficult to see (see Figure 6). The change in the lens is similar to what happens when you cook an egg white—it goes from clear to opaque. Early on, before cataracts cloud vision, they can cause nearsightedness, double vision, or distorted vision.

Figure 6: Cataract vision

As cataracts progress, your vision gradually blurs or dims.

Photo courtesy of the National Eye Institute.

Most cataracts result from age-related changes in the lens. But other factors, such as family history, eye injuries, the use of some medications (particularly corticosteroids such as prednisone), and certain health problems (such as diabetes) can also contribute (see “Are you at risk for cataracts?”). Several studies have linked cataracts with alcohol consumption and smoking. Even if you have smoked for many years, quitting now will help lower the chances of cataracts forming in the future. Long-term exposure to high levels of ultraviolet-B (UVB) rays from the sun is another hazard, and studies have found a greater prevalence of cataracts in people who live in areas with abundant sunlight. Wearing sunglasses can help protect your eyesight and minimize cataract formation.

Are you at risk for cataracts?

Age is the most common risk factor for cataracts. By age 80, more than half of Americans have developed a cataract. You are at higher risk for this common eye problem if you

  • smoke

  • use corticosteroid medications (commonly prescribed for asthma, inflammatory bowel disease, rheumatoid arthritis, and other illnesses)

  • have had an eye injury

  • have diabetes

  • have spent considerable time in the sun

  • are obese

  • are an alcoholic

  • have a family history of cataracts.

Source: American Academy of Ophthalmology.


Diagnosing cataracts

Cataracts are painless and progress slowly. Vision usually turns blurry, hazy, or dim, and glare from lights and the sun can be especially distressing. In the early stages, the eye may become more nearsighted because the denser the lens, the greater its refracting power. Night vision worsens, and colors appear duller. Because most cataracts develop very slowly, many people don’t realize what is wrong until the decline in visual acuity forces them to frequently change their eyeglass or contact lens prescription. These efforts become fruitless, however, because corrective lenses don’t help once the cataract becomes fairly dense.

Anyone who experiences blurring or eye discomfort should visit an ophthalmologist immediately for a full examination, because cataract is only one of several important diseases that affect vision. The doctor will test the sharpness of your vision with a Snellen chart (see “Testing your vision”) and will probably dilate your pupils with drops. By painlessly examining the interior of the eye with a slit lamp, the doctor can see any cataract and assess just how extensive the cloudy patches are. Additional examinations and tests help rule out other eye disorders, such as glaucoma or retinal degeneration.


Preventing cataracts

There is no sure way to avoid developing cataracts. However, because of the link between cataracts and the sun’s ultraviolet radiation, make sure to wear sunglasses as well as a hat or visor whenever you are outdoors (see “Investing in the right sunglasses”). Smoking also appears to raise the risk of cataracts, so if you smoke, quit.

Eating plenty of fruits and vegetables, which contain an abundance of antioxidant vitamins, seems to make people less likely to develop cataracts. Especially helpful are spinach and other dark green vegetables, which are rich in the antioxidants lutein and zeaxanthin.


Coping with early cataracts

In the early stages of cataract formation, you might notice a slight decline in your vision, but not so much that it affects your day-to-day activities. In some cases, the lens simply thickens, causing nearsightedness, rather than becoming opaque. In these instances, the following tips can help:

  • Get a new eyeglass prescription if it improves your distance vision.

  • Increase lighting at home, particularly for close work.

  • Reduce glare by positioning lights directly behind you, focused on the task at hand, and by shielding your eyes from direct light.

  • Get antireflective coating on your lenses.

These measures help many people successfully delay cataract surgery for years—and some end up never needing it.


Do you need cataract surgery?

Surgical removal of the clouded lens is the only effective cure for a cataract. No drugs, eye drops, diets, exercises, or glasses can reverse the problem. For most people, the only choice is when to undergo the procedure. That decision is usually based on how much the cataract is interfering with your vision.

The questionnaire below (“Should you consider cataract surgery?”) can help you determine how much your vision loss is affecting your daily activities and when you should consider an operation. Those who rely on their eyes for detailed work—such as architects, dentists, and jewelers—are likely to require surgery sooner than others. You should be able to delay cataract surgery until you feel that you need better vision, but there is research to suggest that timely cataract surgery can increase safety when driving and decrease risk of falls or depression.

Should you consider cataract surgery?

If you answer “yes” to more than a few of these questions, consider a consultation with an ophthalmologist.

Even with glasses, do you have difficulty

  • reading a newspaper or book?

  • seeing steps or curbs?

  • reading traffic signs, street signs, or store signs?

  • taking part in sports such as bowling, handball, tennis, or golf?

  • watching television?

  • seeing well in poor or dim light?

  • recognizing people, even when they’re close to you?

  • Do you experience

  • glare caused by bright lights or street lights?

  • blurry or hazy vision?

  • halos or rings around lights?

  • poor color vision?

  • Do you

  • avoid driving because of your vision?

  • have difficulty driving at night?

If your doctor determines that you have cataracts in both eyes, he or she may recommend operating first on the eye with the denser cataract (and poorer vision). If surgery is successful and your vision improves substantially, you may elect to forgo surgery on your other eye. However, most people note significant benefits from having the second eye operation, including better depth perception and improvements in their ability to drive and to read. Many people choose to have the second surgery once the first eye has healed and vision is stable. If you are extremely farsighted or nearsighted and need cataract surgery in both eyes, you may want to have the second surgery within about one month of the first surgery. Otherwise, you might have problems with double vision and depth perception because of the difference in the eyeglasses prescription between your two eyes. These problems will resolve once you’ve had surgery in both eyes.

Some people with cataracts have an additional eye problem, such as age-related macular degeneration. In some cases, your doctor may recommend cataract surgery because the cataracts make it difficult to examine and manage the other problem. Whatever the situation, you and your doctor should discuss the rationale for the operation, as well as its benefits and risks.


Types of cataract surgery

Cataract surgery is the most common eye operation in the United States, with more than two million performed each year. Once an inpatient procedure requiring up to a week of hospitalization, cataract surgery today is performed under local anesthesia on an outpatient basis and is considered one of the safest of all surgeries. Most ophthalmologists either are trained to perform cataract surgery or can refer you to someone who is. Ask around to find an experienced surgeon.

Cataract surgery involves removing the clouded natural lens and replacing it with an artificial substitute. There are a variety of approaches for doing this.

Traditional cataract surgery

Unlike some other eye surgeries, traditional cataract surgery does not use lasers, except in some follow-up procedures. To remove the original lens, the surgeon makes a tiny incision in the eye, a delicate procedure done with the aid of special surgical microscopes. The doctor may choose between two main procedures for extracting the lens: phacoemulsification and extracapsular surgery.

Phacoemulsification. This procedure requires only a tiny incision in the cornea that often needs no stitches and heals rapidly. Through this incision, the doctor inserts a thin probe that releases ultrasound waves. These waves break up the clouded lens into tiny pieces. Then the doctor suctions out the pieces. The outer lining of the lens capsule (the membrane that surrounds the lens) is left behind to support the artificial lens implant (see Figure 7). Phacoemulsification—informally known as phaco—offers good long-term results, and 97% to 98% of all cases done by an experienced surgeon are successful and free of complications.

Figure 7: Cataract surgery

The ophthalmologist makes a small incision about an eighth of an inch long in the side of the cornea.

Using a small, needle-like probe called a phacoemulsifier, the doctor directs high-frequency sound waves through the lens to break it into small pieces, which are then gently suctioned out through the probe.

The artificial lens, which is folded to fit inside the probe, is inserted through the same incision.

The new lens unfolds inside the lens capsule and is held in place by tiny loops called haptics.

Extracapsular surgery. This older technique is typically used for very dense or hard cataracts and in other special circumstances. It involves an incision of about three-eighths of an inch in the sclera (the white of the eye) under the upper eyelid, above where the sclera and cornea join. The surgeon opens the lens capsule and removes the harder, central portion of the clouded lens, usually in one piece, and then gently vacuums out the softer part of the lens. The outer part of the lens capsule is left undisturbed, providing support for a replacement lens. After putting in the new lens, the surgeon stitches up the incision.

The main difference between extracapsular surgery and phacoemulsification is that with phaco, most people can resume their normal routine sooner because the smaller incision heals faster. Both procedures restore vision to 20/40 or better in more than 90% of cases.


Laser-assisted cataract surgery

Surgeons typically remove clouded lenses by hand using a metal or diamond-edged blade. But new techniques are being developed that allow surgeons to make incisions and break up a cataract with a femtosecond laser. The pieces are then suctioned out, as in phacoemulsification.

Laser-assisted cataract surgery may provide certain advantages, allowing surgeons to attain a higher degree of safety, efficiency, and precision. For example, creating the corneal incision with a laser rather than with a blade may reduce the likelihood of astigmatism or wound leakage. In addition, to reach the lens, the surgeon must first make a 5-millimeter circular opening in the front part of the clear capsule surrounding the lens. This step is called an anterior capsulotomy. It’s a very delicate procedure, because the remainder of the capsule can’t be damaged—it must be kept intact to hold the new lens in place. Theoretically, performing the capsulotomy with a laser may be more accurate than with a needle. However, this has yet to be confirmed by extensive research.

On the negative side, femtosecond laser–assisted cataract surgery (FLACS) is more expensive—about $4,500 compared with $3,500 for phacoemulsification. And experts say the added costs may not always be worth the benefits. Also, laser-assisted cataract surgery is not yet available at every medical center, and it’s not covered by most insurance plans.



Replacement lenses

After your clouded lens is removed, a clear artificial lens called an intraocular lens (IOL) is implanted to replace it. Many factors affect which IOL is the right choice for you. Here are some questions your surgeon might ask:

  • How do you feel about continuing to wear glasses or contact lenses after your cataract surgery?

  • How important is good night vision for your lifestyle?

  • In general, how well do you adjust to changes and learn new skills?

  • What activities or tasks are part of your daily life, both for work and pleasure?

  • During which activities would you find glasses the most inconvenient or aggravating?

There are two basic types of IOLs—monofocal and multifocal—each with pluses and minuses. There are also some newer types of lenses that aim to address additional problems such as reduced night vision.

Monofocal IOLs

Most people who have cataract surgery receive monofocal IOLs—lenses with a single focal length, like an ordinary pair of glasses. Again, there is a choice in monofocal lenses.

Fixed-focus monofocal lenses can help you see at a distance, but you’ll need reading glasses to see up close. Some people who get monofocal IOLs have one eye fitted with a lens that provides near vision and the other eye with a lens that provides far vision. This combination is called monovision. If you are considering this option, your eye surgeon may recommend that you try out monovision with contact lenses before your cataract surgery to see how well you can adjust to the change. Monovision is usually not an ideal option for people who require crisp, detailed vision.

Accommodating monofocal lenses are a newer option. They do not have multiple focal lengths built in, but they can shift (or accommodate) from near to far vision in response to movements of the ciliary muscles in your eye, similar to the natural lens in a younger eye. These IOLs offer excellent distance and middle vision, but they aren’t as reliable for near vision. Eye exercises can help you get used to them, but about half of people who receive them still end up needing reading glasses.

Toric lenses are specialized monofocal IOLs designed for people with astigmatism. These lenses offer focused vision at a single distance and also correct your astigmatism, so you might not need distance glasses after surgery. Alternatively, to treat astigmatism, the surgeon can use a standard monofocal IOL, but make a few small incisions in the cornea during cataract surgery, known as limbal relaxing incisions, to reshape the curvature of the cornea, making it less like a football and more like a basketball. While toric IOLs and limbal relaxing incisions can treat astigmatism, neither technique will help you focus at a range of distances. However, both techniques may reduce your dependence on glasses either for reading or for distance, depending on which you prefer. One drawback to toric IOLs is the risk that they will rotate out of position, which may require further surgery to reposition or replace the lens.


Multifocal IOLs

Like bifocals or the progressive lenses used in glasses, these IOLs include different areas designed for distance, intermediate, and near vision. The brain and eye figure out which part of the lens to use. One example, the ReStor IOL, uses a type of refractive technology to provide focus for multiple distances. The lens has small, concentric circular ridges that permit the eye to change its range of focus. Another lens, called the ReZoom, has five broad zones to provide distance, intermediate, and near vision. The main drawback of multifocal lenses is they can distort bright light, creating more glare and halos at night.


Newer lenses

IOLs have come a long way in the last few years. Companies that make these lenses are refining several modifications designed to enhance vision after cataract surgery. New IOL design technologies have helped some—but not all—people with cataracts minimize their need for glasses.

Aspheric IOLs. Unlike traditional IOLs, which are spherical (meaning the front surface is uniformly curved), aspheric IOLs are slightly flatter around the edges. These lenses improve the ability to distinguish an object from its background and reduce glare and halos. One aspheric IOL, the Tecnis Z9000, advertises that it can help people see in varying light conditions, such as rain, snow, fog, twilight, and nighttime darkness.

Light-blocking IOLs. A few IOLs include filters that block blue light, the type of light that is thought to increase the risk of age-related macular degeneration and other vision problems. However, some experts say the protection these lenses provide is no better than that of the eye’s natural lens, and that people who receive non-light-blocking IOLs can simply wear sunglasses in bright light to reduce their risk of developing these vision issues.

Three-piece light-adjustable lens. This new technology allows the surgeon to adjust the power of the lens by shining an ultraviolet light on it. As the light hits the lens, it changes shape to correct vision. The doctor can make adjustments several weeks after surgery, once the eye has healed and vision has become stable.



Preparing for cataract surgery

Before surgery, the ophthalmologist will measure the curvature of your cornea and the length of your eye to calculate the power of the implant you need. Your doctor will perform a general medical exam and may request tests to assess your overall health.

He or she may also ask about any medications you take on a regular basis, because you may need to avoid certain drugs before surgery. For example, your doctor may ask you to avoid taking aspirin and other drugs that have an anticoagulant (blood-thinning) effect, especially if the surgery involves larger incisions, because these drugs increase the risk of bleeding during surgery. Note that some people cannot under any circumstances stop taking blood thinners, because of their high risk of developing a blood clot. In these cases, your eye surgeon should discuss the surgery with your primary care physician or cardiologist and may require you to undergo blood testing before your operation. Don’t stop taking any medications on your own without consulting your doctor.

Inform your eye surgeon if you take or have ever taken an alpha blocker. Alpha blockers, which include alfuzosin (Uroxatral), doxazosin (Cardura), silodosin (Rapaflo), tamsulosin (Flomax), and terazosin (Hytrin), are used mainly to treat enlarged prostate in men, but they may be prescribed for high blood pressure or urinary retention in women. These drugs, along with tolterodine (Detrol) and the herb saw palmetto (both used to treat benign prostate enlargement), can interfere with the medications used to keep the pupils dilated during cataract surgery, raising the risk of complications. If the surgeon knows ahead of time that you take one of these drugs, special steps can be taken before or during surgery to avoid these complications. Depending on your medical situation, your doctor may prescribe antibiotic eye drops, anti-inflammatory eye drops, or both before the surgery.


During and after surgery

Local anesthesia (given directly on the eye or by injection) keeps the eye comfortable and immobile during surgery. The entire procedure usually lasts less than half an hour, during which you may see light, hear noises, and be aware of the presence of the surgical team. However, you probably will not see formed images, and you may not be able to tell whether your eye is open or closed. Most people do not have pain during the procedure.

Afterward, the surgeon may cover the eye with a bandage or shield, which may be removed later that day or the following day. Typically you will be discharged after you rest for a while in the recovery area, but you will need someone to drive you home. Reading and watching television are permitted almost immediately. Although it’s a good idea to take it easy, most people can resume normal activities within a few days. Check with your doctor, however, before doing anything strenuous.

Vision usually improves soon after cataract surgery. For some people, vision may be excellent within hours. For others, it may take several days or even a few weeks to return to normal. This longer interval does not necessarily indicate any complication or failure of the surgery.

During the healing process, you may be surprised by changes in color. Because the clouded lens, which commonly filters out some colors, has been removed, colors may appear more luminous or seem to have a bluish glow. Spending time in bright sunlight may give objects a reddish afterimage when you come indoors.

Sticky eyelids, itching, sensitivity to light, and mild tearing are perfectly normal after surgery, but severe pain and sudden changes in vision are unusual and warrant an immediate call to your doctor. People who have minor discomfort can take a non-aspirin pain reliever such as acetaminophen (Tylenol) every four to six hours. Any discomfort should subside on its own within a day or two.

The ophthalmologist will schedule several postoperative visits: the day after surgery, after about a week, at three to four weeks, and then usually six to eight weeks later. The doctor will examine your eye, test your visual acuity, and measure eye pressure. Corrections for eyeglasses will probably not be prescribed until three to six weeks following surgery.

Driving safely as you age

Good driving is a total-body experience involving motor coordination as well as the senses. But vision is key to staying safe behind the wheel. Aging can increase your challenges as a driver, especially if you have an eye condition such as macular degeneration, presbyopia, glaucoma, or cataracts. Stay safe by getting annual eye exams, checking in with your ophthalmologist, and taking necessary precautions.

Invest in new, more powerful glasses to compensate for any vision loss. Consider adding antiglare coating to your eyeglasses to reduce the temporary blindness caused by oncoming headlights at night.

You can adjust your car to suit your needs, as well. Consider installing broader side-view and rear-view mirrors to provide greater peripheral vision, or choose a car with bigger and brighter gauges to help you stay in control.

Simple lifestyle adjustments may also be in order. Perhaps driving in heavy rain or at night is no longer a good idea. For instance, cataracts, which cloud the lens, make night driving particularly difficult. Fortunately, cataract surgery is one of the safest, most common procedures performed in the United States.

To help stay on top of your driving skills, you may take one of the courses offered for older drivers by the AARP (http://www.aarp.org/families/driver_safety) or AAA (www.seniordrivers.org). These courses cover everything from loss of vision, hearing, cognitive function, and motor function to the side effects of common medications.

Elderly drivers do have one advantage: experience. All those years behind the wheel are invaluable when it comes to making sound driving decisions. Older drivers buckle up more frequently—and are far less likely to use cellphones or drive while intoxicated—than people under 50, according to National Highway Traffic Safety Administration polls and other sources. Still, it’s up to the older driver to identify his or her limits and develop a suitable safe-driving plan.

Self-care

Once at home, you will use antibiotic and cortisone drops or ointment, as well as a nonsteroidal anti-inflammatory drug, to prevent infection and reduce inflammation. Wash your hands thoroughly before applying the drops, and avoid touching the bottle tip to your eye. Because the eye is sensitive after surgery, avoid rubbing or touching your eye, and guard against any sudden movement that could jar your head. To avoid accidentally rubbing your eye while you are sleeping, you may need to wear a protective metal eye shield at night for a few days or weeks.

Your doctor or health professional will show you how to clean your eyelids, which may become crusted from discharge.

Many people prefer to wear medium-density sunglasses when outdoors to screen out the glare, even though most implants have ultraviolet blockers (see “Investing in the right sunglasses”).

Make sure you understand all of your doctor’s postoperative care instructions. It’s important that you follow these instructions carefully to help ensure a rapid and full recovery. Discuss any questions you have with your doctor.



Possible complications

More than 98% of people who undergo cataract surgery have improved vision and an uneventful recuperation afterward, assuming they have no other eye disease or serious medical condition. Although cataract surgery is generally very safe, the operation does involve some risk. Fortunately, most complications can be treated with medications, glasses, or a second surgery. The risk of partial or total vision loss is very low.

Following are some potential complications.

Infection of the eye (endophthalmitis). Most ophthalmologists use topical or injected antibiotics before, during, and after surgery to minimize this risk. If you do get an infection (symptoms include red, swollen, painful eyes and a decline in vision), see your doctor right away.

Swelling and fluid in the center of the retina (cystoid macular edema). Symptoms include blurred or reduced central vision. This can be treated with steroid injections or nonsteroidal anti-inflammatory drops. It’s important to take your drops exactly as your doctor prescribed to reduce this risk.

Swelling of the clear covering of the eye (corneal edema). If you have this complication, you’ll probably notice blurred vision or haloes around lights. Corneal edema is often temporary, and it rarely leads to corneal transplant surgery.

Bleeding in the front or back of the eye (hyphema, vitreous hemorrhage, or suprachoroidal hemorrhage). You may see the blood or have symptoms such as blurred vision and floaters. Bleeding often clears on its own, but it can lead to elevated eye pressure and a loss of vision if the bleeding is severe. Occasionally, a second surgery is needed to clear the bleeding.

Retinal detachment. This rare complication is treated with surgery in the eye doctor’s office or hospital operating room (see “Retinal tear or detachment”).

Problems with glare. These can be temporary or permanent. Glare that seriously affects vision is rare.

Dislocation of the IOL. You might notice movement in your vision, or total whiteness, if your IOL dislocates. This can occur soon after the procedure or later. If the lens shifts out of place, it may need to be repositioned with surgery.

Clouding of the portion of the lens capsule that remains after surgery. This is usually not a significant problem. It can be treated with laser surgery, if needed.

Increased pressure in the eye or glaucoma. This is usually temporary. Glaucoma medications can usually control the pressure (see “Glaucoma”).

Astigmatism. This can be managed with glasses or refractive surgery.

Eye muscle imbalance (strabismus). Your eyes will be crossed, they won’t focus on the same object at the same time, or you’ll have double vision. This is sometimes temporary, but if it is permanent, it can be treated with eyeglass modifications (prisms) or, rarely, eye muscle surgery.

Drooping of the upper eyelid (ptosis). If the drooping is severe, it can be treated with lid muscle surgery (see “Ptosis”).



Glaucoma

Nearly three million Americans over age 40 have glaucoma, according to the Glaucoma Research Foundation, but about half of them don’t know it because the early stages of the disease usually progress without symptoms. By the year 2030, experts estimate, that number will rise to 4.2 million people. Glaucoma is a major cause of blindness, accounting for up to 12% of all cases of total vision loss. The problem increases with age. Glaucoma threatens sight in 2% of people over age 40, but up to 10% of those over 80. Early diagnosis and treatment can almost always save vision.

What causes glaucoma?

Glaucoma is a group of eye diseases that cause vision loss through damage to the optic nerve. Doctors used to think that high pressure within the eye, called intraocular pressure, was the only cause of this damage, but they now know that other factors besides pressure must be involved, because some susceptible people with “normal” intraocular pressure can experience vision loss from glaucoma.

Normally, the aqueous humor—the liquid that fills the area behind the iris—circulates through the pupil into the front compartment of the eye, nourishing the lens and the cells lining the cornea. It then passes through a circular, sieve-like system of tissues called the trabecular meshwork and drains out of the eye through Schlemm’s canal. From there, it is absorbed into surrounding blood vessels. The process works continuously as more aqueous humor is produced and excess fluid is eliminated through the trabecular meshwork to keep a healthy balance of pressure in the eye (see Figure 8).

Figure 8: The anatomy of glaucoma

In a healthy person, the ciliary body continuously produces aqueous humor, a clear liquid that circulates from the posterior chamber into the anterior chamber of the eye and helps maintain its shape and pressure. The fluid (see arrows) bathes and nourishes the interior of the eye, then drains through the trabecular meshwork into small blood vessels.

If this sieve-like meshwork is blocked, aqueous humor accumulates, and pressure inside the eye increases, causing closed-angle glaucoma. In open-angle glaucoma, the meshwork remains open, but the fluid drains too slowly. In both cases, the excess fluid places undue pressure on the optic nerve in the back of the eye (not shown), and nerve fibers gradually begin to die off, leading to vision loss.

In glaucoma, this drainage system breaks down, slowing or blocking the outflow of fluid. The fluid backs up in the eye, much like water in a clogged sink, and internal pressure rises. This, in turn, puts stress on the optic nerve, which provides the eye’s wiring to the brain. If the pressure continues unabated, nerve fibers that carry the optical messages begin to die off, and vision starts to fade. Loss of vision may also result from the obstruction of tiny blood vessels that feed the retina and optic nerve. Nerve fibers on the outer edge of the optic nerve are typically affected first, so vision loss begins with peripheral vision (see Figure 9) and gradually closes in until the cells supplying central vision are lost. The damage that occurs in glaucoma is irreversible.

Figure 9: Glaucoma vision

As glaucoma progresses, you may notice that your peripheral vision diminishes.

Photo courtesy of the National Eye Institute.

While pressure plays an important role in most glaucoma cases, other mechanisms also appear to cause cell death in nerve fibers. Scientists are now investigating ways to prevent this cell death through several different strategies, collectively known as neuroprotection. However, the results of studies on neuroprotective treatments could still be years away. For now, drugs to lower intraocular pressure remain the mainstay of treatment for glaucoma.


Types of glaucoma

Although more than two dozen types of glaucoma exist, the following affect the greatest number of people.

Open-angle glaucoma

This is the most common form of the disease, accounting for more than 90% of all cases. It strikes black and Hispanic people far more frequently than whites, is most prevalent in people over 60, and tends to run in families.

The name comes from the fact that the angle through which fluid drains from the anterior chamber of the eye remains open, yet the aqueous humor drains out too slowly, leading to fluid backup and a gradual but persistent elevation in pressure. Ultimately this damages the optic nerve and causes vision loss if not controlled in time with medication. Because the condition generally has no symptoms in its early stages, regular eye exams are important, especially for anyone at increased risk.

You are at higher risk for open-angle glaucoma if any of the following apply to you—specifically, if you

  • are African American or Hispanic

  • are over age 60

  • are severely nearsighted or farsighted

  • have had an eye injury or eye surgery

  • have a family history of the condition

  • have thin corneas (see “The importance of corneal thickness”)

  • have high intraocular pressure

  • use corticosteroid medications.

The importance of corneal thickness

Roughly a decade ago, researchers discovered that the thickness of your cornea (the clear part of the eye’s protective covering) plays a role in the accuracy of your eye pressure reading. Many times, people with thin corneas (less than 540 micrometers) have artificially low intraocular pressure readings. If your actual pressure is higher than the reading indicates, you might have glaucoma without realizing it.

On the other hand, people with thick corneas may show an artificially high pressure reading, which could lead to unnecessary treatment.

Fortunately, there is a quick, painless test, called a pachymetry test, to measure corneal thickness. The measurement (done routinely with pressure screenings) enables your doctor to better understand your intraocular pressure reading and develop an appropriate treatment plan.


Closed-angle glaucoma

In closed-angle glaucoma, pressure in the eye rises rapidly as the angle between the iris and cornea narrows and the iris suddenly blocks the trabecular meshwork, preventing fluid from flowing out. When this form of the disorder occurs, the eyeball quickly hardens and the pressure causes pain and blurred vision. Also, people often see halos—colored rings around lights (see “Symptoms of glaucoma”). This condition is a medical emergency and should be treated right away.

You are at higher risk for closed-angle glaucoma if you

  • are Asian

  • are farsighted

  • are female

  • have a shallow anterior chamber or small eye (short axial length).

Symptoms of glaucoma

Open-angle glaucoma

  • Few or no symptoms in early stages

  • Blind spots and diminishing peripheral vision in later stages

Closed-angle glaucoma

(This is a medical emergency; call your doctor immediately.)

  • Severe pain

  • Nausea

  • Colored halos around lights

  • Eye redness

  • Blurry vision or rapid vision loss


Low-tension or normal-tension glaucoma

In this less common condition, the optic nerve suffers damage typical of glaucoma, but at normal eye pressures. Symptoms don’t usually appear until late in the disease, when blind spots may occur in peripheral vision. The diagnosis is often made after there has been some vision damage, but more sensitive diagnostic techniques are making it possible to detect this disease earlier, before peripheral vision is lost. After other possible causes of the optic nerve damage and visual loss have been ruled out, you can usually stabilize the condition by lowering the pressure even further with medication, surgery, or both.

You are at higher risk for low-tension glaucoma if you

  • have abnormal blood flow in the eye

  • have an autoimmune disease

  • have low blood pressure.

Your risk for normal-tension glaucoma increases if you have a disorder that affects blood vessels, such as migraines or Raynaud’s phenomenon. Several studies also suggest that obstructive sleep apnea—repeated pauses in breathing that occur while you’re asleep—can affect blood flow to the optic nerve and increase optic-nerve damage in people with glaucoma.


Congenital glaucoma

This rare condition is present at birth and is often inherited. It is attributed to a structural defect in the drainage angle and is frequently found in both eyes. Usually, children with this condition are more sensitive to light. Their corneas may be cloudy and their lacrimal glands may produce excessive amounts of tears.


Secondary glaucoma

Secondary glaucoma may develop as a result of some other eye problem—such as longstanding inflammation, injury, cataract, diabetes, or blood vessel blockage in the eye—or, rarely, as a complication of cataract surgery. Corticosteroids (oral, inhaled, or topical) can also increase intraocular pressure, especially in people with glaucoma or a family history of glaucoma. People who take these medicines should have their eye doctor carefully monitor their eye pressure.



Progression of glaucoma

Except in the case of closed-angle glaucoma (which can appear suddenly with pain and blurred vision), glaucoma often has no symptoms in its early stages. Even blind spots or diminishing peripheral vision may not be noticeable until the disease is already advanced. Occasionally, people realize something is awry when they repeatedly need new eyeglass prescriptions or have trouble adjusting to the dark. However, these symptoms generally occur later in the disease. The good news is that vision loss from glaucoma can be prevented if the condition is discovered before the nerve is damaged. This makes regular screening for glaucoma beginning at age 40 very important.

Symptoms are much more obvious in closed-angle glaucoma. Most people experience blurred vision, eye pain, rainbow halos around lights, headaches, nausea, and vomiting. This is a serious condition that can cause blindness in a relatively short time. Go to an emergency room if you can’t get through to your ophthalmologist right away. Left untreated, glaucoma can lead to tunnel vision and eventual blindness.


Diagnosing glaucoma

Most doctors agree that a regular eye exam should include glaucoma screening beginning at age 40, and people who are at higher risk should be screened annually.

During your exam, the ophthalmologist evaluates pressure in the eye using tonometry (see “Measuring eye pressure”). Normal pressure is 8 to 21 millimeters of mercury (mm Hg), but people with eye pressure in this range may still develop the disease (see “Low-tension or normal-tension glaucoma”). Conversely, those who have slightly elevated pressure might never develop glaucoma. The amount of stress the optic nerve can withstand differs for each person and each eye.

The doctor will use both a slit lamp and an ophthalmoscope to look for any deterioration of your optic nerve. If the front surface of the nerve (the optic disc) is affected by glaucoma, the doctor may see a characteristic called cupping: the disc may appear indented, and its color—normally pinkish yellow—may turn pale and more yellow because the advancing disease has hindered blood flow to the area.

If your eye pressure is not in the normal range or your optic nerve looks unusual, the doctor will perform one or two specialized glaucoma tests:

  • Visual field test. Also called perimetry, this test requires you to look straight ahead and indicate whether you see lights flashing on and off in different locations within your peripheral (side) vision.

  • Gonioscopy. This procedure involves placing a special contact lens on the surface of an anesthetized eye. The lens has mirrors and facets that, when studied through the slit lamp, give a detailed view of the corner of the eye and show whether the drainage angle is open, narrowed, or closed.

To confirm the presence of the disease, the doctor may repeat the tonometry test, since pressure in the eye may vary at different times of the day.

If you have glaucoma, your ophthalmologist may use a technique called fundus photography to produce three-dimensional pictures of the optic disc. These images serve as a baseline for later comparisons of the disc. If the disc changes over time, your pressure hasn’t been well controlled and you need more aggressive treatment. Several newer techniques create computer-generated images that analyze fiber layers of the optic nerve. Over time, they can detect the loss of optic nerve fibers, allowing the doctor to track the progression of the disease.

Home testing for glaucoma

Regular glaucoma checks from your ophthalmologist are an accurate and effective way to make sure your eye pressure stays under control. But having the ability to test your eye pressure at home could help your doctor better monitor your progress and quickly make adjustments to your medications, if needed.

One home device, called the Proview Eye Pressure Monitor, measures pressure through the eyelid based on phosphene—a sensation of light produced in the eye by something other than light. To see a phosphene, close your eye and gently press your finger on your eyelid where it meets the nose. The phosphene appears as a bright central area surrounded by a dark ring with an outer bright halo. The eye pressure monitor works by gently applying pressure with a pencil-like probe on the eyelid until you see the phosphene ring. The device then converts the input to a pressure measurement. Further studies are under way to evaluate the device’s accuracy.

Another promising home monitoring method is called iCare Home. In studies, about 75% of people were able to use this device themselves and got results similar to those of devices used by ophthalmologists. iCare Home is not yet FDA-approved, but it could be an option in the future.

You can also use one of several online tools to check your peripheral vision, but experts typically don’t recommend these tests because the results haven’t been fully validated and may be inaccurate. If you choose to use the Proview Eye Pressure Monitor or an online test, first check with an ophthalmologist.


Treating glaucoma

Most types of glaucoma—including open-angle glaucoma, the most common type—can be controlled but not cured. No treatment can restore vision lost to the damage of glaucoma, but it is possible to stop the progression of the disease by keeping pressure under control. Studies have shown that lowering eye pressure prevents optic nerve damage and vision loss in people with all stages of glaucoma—from those who are newly diagnosed to those with advanced disease. Lowering eye pressure can even protect your vision if you don’t have glaucoma but your eye pressure is high (ocular hypertension).

For open-angle glaucoma, treatment usually begins with topical medications—eye drops or sometimes ointments—administered one to several times a day (see Table 3). Depending on the severity of the condition, multiple drops and sometimes pills may be required. Most ophthalmologists begin with the lowest effective dose to minimize cost and potential side effects.

You can apply drops best by tilting your head back while standing and pulling your lower lid out to create a small pouch for the medicine. Let the drop fall into the pocket. Gently close your eye to ensure that the medicine spreads over its surface. Try not to blink, squint, or shut your eyes too tightly, as these could push the drops out of your eyes. To minimize the amount of medicine that gets into your bloodstream, press your fingertip against the inner corner of the eye for two to three minutes after adding the drops. This compresses the tear duct and prevents the medicine from entering the drainage pathway into the nose. Generally, drops should be used every 12 hours if prescribed twice a day, every eight hours if prescribed three times a day, and so forth.

Although eye drops help control pressure in the eye, they may have side effects that can keep you from using them. These side effects may affect just the eye or your whole body, as the drops can enter your bloodstream through your nose and throat. (That’s why you should press the inner corner of the eye for two to three minutes after applying the drops.) If you have questions about your drugs, trouble following your treatment plan, or difficulty using your medicine, ask your doctor for advice and solutions.

Regular exams are equally important. Without an exam, you can’t know whether pressure in your eye is in a safe range or if your visual field is slowly deteriorating. Each year, people with glaucoma typically undergo two to four exams to check visual acuity, the optic nerve, and eye pressure. The visual field test and other tests are done at selected intervals to determine whether the disease is stable or if it’s worsening—a problem requiring more aggressive treatment.

In some respects, treatment of glaucoma is similar to that of heart disease. Both conditions may require multiple medications to manage the condition. And in both cases, therapy represents a lifetime commitment. Furthermore, it’s important to adhere to your treatment plan even when you may not feel any benefit, because quite often benefits are not immediately obvious. Take eye pressure, for example. Like blood pressure, intraocular eye pressure varies over the course of the day. Because an important goal of glaucoma treatment is to control eye pressure and stop the progression of the disease, your physician may tailor your medication schedule to address such fluctuations in eye pressure. Follow your doctor’s treatment recommendations and take your medications regularly to manage your glaucoma and preserve your vision.

Table 3: Glaucoma medications

These drugs are taken topically as eye drops, unless otherwise noted.

Generic name (brand name)

Doses per day

Side effects/comments

Adrenergics

dipivefrin* (AKPro, Propine)

2–3

Headache, stinging, redness, burning, temporary blurring of vision. May cause pounding heart and fast heartbeat in some people.

Alpha agonists

apraclonidine* (Iopidine)

brimonidine* (Alphagan)

2–3

Stinging, burning, redness of the eyes, dry mouth, blurred vision, fatigue. Minimal effect on the lungs and cardiovascular system.

Beta blockers

betaxolol* (Betoptic, others)

carteolol* (Cartrol, Ocupress)

levobetaxolol (Betaxon)

levobunolol* (AKBeta, Betagan)

metipranolol* (OptiPranolol)

timolol maleate* (Betimol, Istalol, Timoptic-XE)

1–2

Stinging, irritation, blurred vision, tearing, allergic reaction. Elderly people are especially prone to side effects. May cause breathing problems in people with asthma. Can slow heart rate in those with heart disease. May cause mental and physical lethargy. Men may experience a decrease in libido.

Carbonic anhydrase inhibitors

Oral

acetazolamide* (Diamox)

methazolamide* (Neptazane)

2–3

Dizziness, diarrhea, loss of appetite, metallic taste in the mouth, numbness or tingling in hands and feet, weight loss, fatigue, excessive urination, anemia. Can lead to loss of potassium.

Topical

brinzolamide (Azopt)

dorzolamide hydrochloride* (Trusopt)

2–3

Burning, stinging, bitter taste in mouth, corneal inflammation, allergic reaction. Dorzolamide is also available in oral form; drops have fewer side effects for most people.

Miotics

echothiophate (Phospholine Iodide)

3–4

Blurred vision, change in near or distance vision, reduced night vision, headache, eyelid twitching, tearing, sweating, diarrhea.

pilocarpine* (Betoptic Pilo, Isoptic Carpine, Pilopine HS Gel, Ocusert Pilo, others)

Blurred vision, change in near or distance vision, reduced night vision.

Prostaglandins

bimatoprost* (Lumigan)

latanoprost* (Xalatan)

tafluprost (Zioptan)

travoprost (Travatan)

1

Burning, stinging, itching, redness, blurred vision. Used only once a day; some people report growth of lashes or change in eye color due to increase in brown pigment in the iris.

Combination medications

brinzolamide plus brimonidine tartrate (Simbrinza)

timolol plus dorzolamide hydrochloride* (Cosopt)

timolol plus brimonidine (Combigan)

2

A more convenient option for people who need more than one type of medication.

Another class of glaucoma medications known as hyperosmotics is used only to control sudden elevations in eye pressure. Hyperosmotics are given orally or by injection; examples include glycerin (Osmoglyn) and isosorbide (Ismotic).

*These medications are available in generic versions.

Glaucoma medications

The following classes of drugs are listed in the order in which an ophthalmologist is most likely to prescribe them. However, the doctor will adjust treatment to your individual needs. Depending on the severity of your glaucoma and your medical history, your doctor may prescribe these drugs in a different order or use two or more drugs in combination. The more commonly used medications tend to have fewer and less severe side effects than those less commonly prescribed (see Table 3).

Prostaglandins. Many people use prostaglandin eye drops because they require only one application per day. Prostaglandins lower eye pressure by increasing the flow of aqueous humor through the uveal and scleral tissues.

Beta blockers. These eye drops contain medication similar to the beta blockers that are used to treat some types of heart disease. Beta blockers lower pressure in the eye by reducing the amount of aqueous humor produced by the ciliary body. This class of medication is usually well tolerated, but side effects may occur. You may use topical beta blockers even if you are also taking beta blockers in pill form for heart disease, but you should notify both your ophthalmologist and physician that you are doing so.

Carbonic anhydrase inhibitors. Medications in this class, also known as CAIs, can be used either orally or topically to decrease eye pressure by reducing the amount of aqueous humor produced in the eye.

Alpha agonists. These eye drops lower pressure in the eye by both decreasing production of aqueous humor and increasing the fluid outflow.

Adrenergics. These drugs reduce the amount of aqueous humor and increase its outflow through the trabecular meshwork.

Miotics. These are the oldest of the current glaucoma medications. Applied as eye drops, they improve the drainage system. Today miotics are not used as often because they have more side effects—including dim vision at night or in darkened rooms—than many other glaucoma medications.

Hyperosmotics. Hyperosmotic medication is used for closed-angle glaucoma. It can be taken by mouth or injected intravenously. The medication quickly reduces pressure in the eye by pulling fluid from the eyeball into the blood vessels inside the eye. The fluid then leaves the eye with the normal blood flow.

Potential new drugs. Researchers are currently investigating new treatments to lower eye pressure. Some therapies under development improve the function of retinal ganglion cells—the nerve cells that transmit visual information from the eye to the brain. Other potential new therapies protect the optic nerve through various mechanisms.


Glaucoma surgery

If medication fails to control your eye pressure, your ophthalmologist may recommend either laser or incisional glaucoma surgery.

Laser trabeculoplasty. This procedure uses very focused light energy from lasers to treat open-angle glaucoma (see Figure 10). There are two versions: argon laser trabeculoplasty and selective laser trabeculoplasty. Both treatments effectively lower eye pressure more than 75% of the time.

Figure 10: Laser trabeculoplasty for glaucoma

In this procedure, the surgeon uses a high-energy beam of light (laser) to produce small burns on the trabecular meshwork. The light energy tightens the beams of the trabecular meshwork, enhancing the flow of aqueous humor out of the eye. It also causes metabolic changes in the drainage system by recruiting cells called macrophages and other cells that enhance the activity of the drain.

Laser trabeculoplasty is done in an ophthalmologist’s office, and it usually takes less than 10 minutes. After you receive anesthetic drops to numb your eye, the doctor puts a temporary contact lens on your eye, then focuses and applies the laser. You may see flashes of green or red light during the procedure, but you won’t feel any pain. The doctor then checks your eye pressure and prescribes anti-inflammatory eye drops for use at home. You may experience blurred vision and sensitivity to light for a day or two after the operation, but real discomfort is rare. You’ll probably still need to keep taking your regular glaucoma medicines after the procedure.

Laser trabeculoplasty is often helpful, but the benefits aren’t permanent. As the treatment effect wanes (usually within two to three years), you may need additional medicines or more surgery.

Laser iridotomy. Doctors use this procedure to treat people who have closed-angle glaucoma or are at risk for it. Like trabeculoplasty, this procedure is done in an ophthalmologist’s office. After numbing your eye and applying a temporary contact lens to guide the laser, the doctor creates a tiny hole—no bigger than the head of a pin—in your iris. The new hole allows fluid to drain from your eye. This restores the balance between fluid entering and leaving your eye and stabilizes eye pressure. The actual procedure takes only a few minutes. Laser iridotomy often cures closed-angle glaucoma. Occasionally, people who have this procedure need additional treatment with medications or incisional surgery.

Incisional glaucoma surgery. If medications or laser treatment fail to lower your eye pressure enough, you may need incisional surgery.

Glaucoma filtration surgery (trabeculectomy) is the most common type of incisional surgery. This delicate microsurgical procedure is done in an operating room under local anesthesia. The eye surgeon makes a small flap in the sclera (the white of the eye). This creates a reservoir called a filtration bleb under the conjunctiva, the thin, clear coating covering the sclera. The aqueous humor inside the eye can then drain through the flap to collect in the bleb, where it is absorbed by blood vessels and other nearby tissues. The doctor closes the flap with tiny stitches. Some of these stitches may be removed after surgery to increase fluid drainage and lower the pressure inside your eye. You will likely receive medications to help reduce scarring in your eye both during and after surgery.

Other approaches. If your doctor is concerned that a trabeculectomy will not be successful, he or she may recommend an aqueous shunt. This is a small valve with a tube. The doctor places the valve under the conjunctiva and sews it to the sclera, then inserts the tube into the anterior chamber. The shunt drains excess fluid into the filtration bleb—the small reservoir between the conjunctiva and sclera. Another option is to implant a stent—a small titanium tube—in the meshwork between the iris and cornea to improve fluid drainage and decrease eye pressure.

Incisional surgery helps to lower eye pressure in many people, allowing them to reduce or even stop taking their glaucoma medications. However, up to 20% of people need a second surgery. The filtering blebs created by this surgery may leak, become infected, or fail to form. Incisional surgery may also lead to blurred or reduced vision or the development of a cataract.

Cyclophotocoagulation. Doctors use cyclophotocoagulation for advanced or aggressive open-angle glaucoma when other treatments fail to remove excess fluid from the eye. This procedure can be done without incisions through the eye wall, or during intraocular surgery, to help control eye pressure. A laser is aimed at the ciliary body, the structure behind the iris that produces aqueous humor, to help reduce the amount of fluid entering the eye, which in turn lowers eye pressure. Although serious complications are uncommon, this surgery can cause inflammation and may increase the risk of a cataract.

Newer surgical options. Half a dozen new surgical procedures are able to lower intraocular pressure by rerouting the aqueous fluid in a more natural way, through Schlemm’s canal.

  • Ab interno trabeculotomy is a minimally invasive procedure that uses an electric current to remove tissue from the trabecular meshwork and open up the drainage system.

  • Canaloplasty uses a small incision to widen the eye’s drainage canal, allowing more of the aqueous fluid to drain out.

  • Deep sclerotomy makes a tiny incision into the sclera to provide a new drainage route.

  • Ex-Press mini shunt is a small steel device used during the trabeculectomy procedure to reduce the risk of excessively low eye pressure—a possible complication of glaucoma surgery.

  • iStent is a tiny titanium device that is implanted during cataract surgery. It creates a permanent opening in the trabecular meshwork to improve the flow of fluid from your eyes and control eye pressure.

  • Viscocanalostomy inserts a gel-like material called viscoelastic into Schlemm’s canal. This improves drainage and lowers eye pressure.

All of these procedures are still being studied to confirm their effectiveness and safety over time.




Age-related macular degeneration

Unlike glaucoma, which first affects peripheral vision, age-related macular degeneration (AMD) affects central vision. It strikes at the macula—the small central part of the retina (measuring only about 3 by 5 millimeters, or less than one-quarter-inch square) that is responsible for sharp images at the center of your visual field. People with AMD often develop blurred or distorted vision and cannot clearly see objects directly in front of them. Eventually they may develop a blind spot in the middle of their field of vision that increases in size as the disease progresses (see Figure 11).

Figure 11: Age-related macular degeneration vision

As age-related macular degeneration progresses, you may notice a blind spot develop in your central vision.

Photo courtesy of the National Eye Institute.

Although AMD eventually can become debilitating, in the earliest stages there often are no symptoms. If the condition progresses to intermediate AMD, some people begin to notice blurring or distortion in the center of their vision. At the advanced stage, the blurred area increases, making it hard to read or even recognize people. Ten million to 15 million elderly Americans have AMD, and about seven million of those are at risk of progressing from the less serious form (dry AMD) to the more serious forms (advanced dry AMD and/or wet AMD; see “Types of AMD”). AMD is the leading reason for loss of close-up and detailed vision in adults 65 and older.

Symptoms of AMD

Report any of the following symptoms to your doctor:

  • Blurred vision

  • Distorted vision

  • Faded colors

  • Difficulty reading

  • Difficulty distinguishing faces

  • Blind spot in the center of the visual field

Types of AMD

The disease occurs in two main forms: dry and wet. While this discussion focuses on these two age-related forms, younger people may develop other kinds of macular degeneration, some inherited and some acquired, which may have similarities to age-related macular degeneration.

Dry AMD

The vast majority (90%) of people with AMD have the dry or atrophic type. This form of the disease is caused by a breakdown or thinning of retinal tissue and, in its advanced stages, by the loss of photoreceptor (light-sensitive) cells in the macular area of the retina. Although some people have no symptoms and are completely unaware that they have the disease, others completely lose their central vision.

Dry AMD has three stages—early, intermediate, and advanced. In the early stage, central vision is usually not affected, though there are some small abnormalities. In the intermediate phase, a blind spot and blurring may appear. Dry AMD may affect only one eye at first, causing gradual distortion of the visual field and blurring of central sight. It is likely that the second eye is also affected, but with no symptoms. However, the disease may continue to develop in the second eye and show symptoms over time. After five years with intermediate dry AMD, the risk increases of developing advanced dry AMD, in which blurring becomes more pronounced.


Wet AMD

All people with wet AMD start out with the dry form. Although wet AMD is less common than dry AMD, it is the form of the disease most likely to cause severe vision loss. By definition, it is an advanced form of the disease. It progresses more rapidly, and vision loss can occur suddenly. It results when abnormal blood vessels develop in the layer of cells beneath the retina (the choroid layer) and extend like tentacles under and into the retina, often toward the macula. These new vessels are prone to leaking fluid and blood, which damage tissue and photoreceptor cells. The result is scarring and marked loss of vision, usually in the center of the macula.

What is a macular hole?

A macular hole is different from and less common than macular degeneration. It occurs when the vitreous humor, the gel-like substance that fills the back of the eye, pulls away from the surface of the retina, creating traction that may cause a hole to develop in the macula. In severe cases, a person with this condition will lose much of his or her central vision.

Ophthalmologists use a procedure called vitrectomy and membrane stripping with gas injection to close the hole and possibly restore vision. The doctor removes the vitreous humor to prevent it from pulling on the retina, along with any visible scar tissue, and fills the resulting space with a gas bubble. If you have this procedure, you must spend a few days to a week in a face-down position, to allow the gas bubble to push against and gradually seal the hole at the back of the eye. This procedure is more than 90% effective in closing the hole, but the degree of vision improvement varies widely from person to person. Outcomes are best when the surgery is performed early in the course of the disease (typically within the first few months), although visual improvement is commonly seen when it’s done within one year.



Causes and risk factors

The causes of AMD are not well understood. Scientists don’t know exactly why the macula deteriorates. But they do know that certain factors can increase your risk of developing AMD.

Aging. People in their 50s have only a 2% chance of developing any form of AMD, yet that risk jumps to 30% in those older than 75.

Gender. Women (who tend to live longer than men) get the disorder more often.

Race. White people are more likely to get AMD, and to lose their vision from it, than people of other races.

Smoking. Smokers have up to four times the risk of developing the later stages of macular degeneration. Quitting lowers your risk, with benefits becoming evident after a year of being smoke-free.

Other factors that may increase risk include

  • coronary artery disease

  • unprotected exposure to bright sunlight and ultraviolet radiation

  • family history of AMD

  • farsightedness

  • high blood pressure

  • high cholesterol

  • light-colored eyes

  • nighttime drop in blood pressure

  • obesity

  • sleep apnea.

There has been some question as to whether cataract surgery may play a role in the development of AMD, particularly because many older adults have both conditions. However, recent research hasn’t supported this idea.

Diet may play a role in the development of AMD. Studies have found that AMD is more common in people whose diets are deficient in nutrients such as vitamins C and E, the mineral zinc, and lutein and zeaxanthin (substances known as carotenoids that are found in green leafy vegetables and fruits and are also the dominant pigments in the macula). A diet high in refined carbohydrates and sugary foods such as cakes, cookies, and white bread, as well as one that’s high in saturated fat, may also raise the risk of AMD.

Ongoing research continues to focus on causes—such as genes, diet, and environmental conditions—with the hope of ultimately preventing AMD. Researchers have identified several gene variants that are linked to a higher risk of developing AMD, including the complement factor H gene. A few genetic tests for AMD are commercially available. However, the American Academy of Ophthalmology doesn’t recommend gene testing for AMD, because with no real preventive therapies currently available, testing can’t do much, if anything, to change the disease course. Genetic information may be more valuable in the future, as new treatment options emerge.


Diagnosing AMD

Often there are no symptoms in the early stages of the disease. As AMD progresses, people with the dry form will experience blurred vision and difficulty reading or distinguishing faces. These can also be symptoms of early stages of wet AMD. Wet AMD typically progresses swiftly if left untreated, causing a blind spot at the center of the visual field. Over time, this area may enlarge and hinder sight. However, some people who have AMD in only one eye often do not realize they have any vision loss because their healthy eye compensates so well.

Distorted vision is another early sign of wet AMD. Leaking blood vessels raise the position of the macula and cause straight lines to suddenly appear wavy and shapes to look deformed. Colors may seem faded. While AMD can severely damage central vision, it does not affect peripheral vision, and people do not go totally blind from even the most severe forms of the disease.

A routine dilated eye examination can often detect signs of AMD before sight is affected and permanent visual loss occurs. The eye exam includes an acuity test to measure how well you see at different distances (with glasses, if needed). A complete eye exam will rule out or identify coexisting eye diseases, such as cataract or glaucoma.

A doctor may suspect dry AMD if the view through an ophthalmoscope reveals clumps of pigment or clusters of drusen (small yellow deposits that build up under the macula). Although these lesions can indicate early or intermediate stages of dry AMD, drusen alone are not conclusive evidence that you have the disease.

If the doctor suspects wet AMD, you may have additional tests to confirm the diagnosis and help determine the best course of treatment.

Fluorescein angiography. A special dye is injected into your arm. As the dye travels through the blood vessels in the retina, your doctor uses a special camera to take images that reveal whether the blood vessels in your eyes are leaking and where any abnormalities are located.

Indocyanine green (ICG). This test uses another special dye to view blood circulation in your retina and look for various components of retinal disease.

Optical coherence tomography (OCT). This test uses ultrasound to take pictures of your retina. It can show fluid in the retina—a sign of wet AMD.


Monitoring AMD

The earlier the progression to wet AMD is detected, the greater the likelihood of successful treatment. That’s why it’s important for anyone with dry AMD to get in the habit of checking their central vision at home once or more a week to catch the progression to wet AMD.

A good way to do this is with the Amsler grid test (see Figure 12). You focus your eyes on a central dot on a grid that resembles graph paper. If the lines near the dot appear wavy or are missing, AMD may be to blame. (You can simulate this test on your own by looking at windowpanes, floor tiles, or ceiling tiles. See if the straight edges look wavy.) Distortion that appears on the grid may be a sign of the wet form of AMD and should be evaluated, especially if it represents a change from previous observations. If you already show evidence of dry AMD, it’s a good idea to perform this test regularly to check for signs of progression to the wet form of the disease. You can find the Amsler grid and instructions for using it online. (www.preventblindness.org/amsler-grid-instructions ), or download an app on your smartphone.

Figure 12: When central vision is damaged

When the macula is damaged, you may first experience blurred or distorted vision and see straight lines as wavy. As the condition progresses, you may notice a black or dark space at the center of your visual field. An ophthalmologist may ask you to focus on a dot on a visual grid (the Amsler grid). If the lines near the dot appear wavy, macular degeneration may be responsible.

A device called ForeseeHome also allows for home AMD monitoring with a few simple tests that measure your ability to detect a wave in a straight line. The device is relatively small—about the size of a tabletop microscope. To use ForeseeHome, you must pay a one-time activation fee and a monthly monitoring fee (though the activation fee can be waived if you give the code FSH4AMD when you order). The daily test takes a few minutes per eye, and the results are automatically sent via phone to a monitoring center. If the monitoring detects a change in your test results, the company alerts you and your doctor to schedule an appointment. A large, government-sponsored study was conducted to better understand the potential benefits of this device. In response to highly positive outcomes, the trial was stopped before it was completed. People who used ForeseeHome were more likely to have better vision and fewer symptoms, because the device detected wet AMD earlier in its course. Research shows that the better your vision is when you start treatment, the better your outcome.


Treating dry AMD

Currently, the only treatment for dry AMD is a well-balanced diet that includes leafy green vegetables—combined with supplements of vitamins studied in the federally funded Age-Related Eye Disease Study (AREDS). This study found that daily high doses of vitamins C and E, beta carotene, and the minerals zinc and copper can slow (and sometimes even prevent) progression from intermediate to advanced AMD, thereby preserving vision in many people (see “Vitamins for AMD”). A follow-up study, AREDS2, aimed to determine whether the formulation might be improved by adding omega-3 fatty acids, lutein, and zeaxanthin; removing beta carotene; or reducing zinc. In this subsequent study, adding lutein and zeaxanthin didn’t have an effect on AMD progression, but these antioxidants were safer than beta carotene for people who currently smoke or who recently stopped smoking, and they were particularly helpful for people who were deficient in these carotenoids.

Vitamins for AMD

The clinical trial known as AREDS found that a combination of antioxidants and zinc may help protect against advanced age-related macular degeneration. The follow-up study, AREDS2, tested the following formulation:

  • vitamin C: 500 milligrams (mg)

  • vitamin E: 400 international units (IU)

  • zinc: 25 mg

  • copper (cupric oxide): 2 mg

  • lutein: 10 mg

  • zeaxanthin: 2 mg

  • omega-3 fatty acids (DHA and EPA): 1,000 mg.

AREDS2 substituted lutein and zeaxanthin for the beta carotene in the previous formulation, because they are safer for smokers. Also, the dose of zinc was lowered to prevent stomach upset and other side effects from the previously higher zinc dose. Copper was included because high levels of zinc may cause copper deficiency.

Several innovative treatment approaches are also being evaluated, and while the results won’t be available for several years, there is hope for a new dry AMD drug in the future. Treatments under development include oral medicines that minimize the accumulation of toxic byproducts in the eye, and an injected medication that blocks the buildup of inflammatory substances in the retina. One drug that has shown promise for slowing the progress of late-stage dry AMD is lampalizumab—a monoclonal antibody that works by inhibiting an enzyme involved in the development of macular degeneration. You can search online for a listing of clinical trials evaluating these and other treatments at http://www.clinicaltrials.gov.

Because dry AMD progresses very slowly, people are usually able to manage well in their daily routines, even with some central vision loss. If the condition worsens, special low-vision aids—such as magnifying lenses or devices that “read” regular print and then enlarge it on a monitor—can help maintain quality of life (see “Living with low vision”).


Treating wet AMD

The development of anti-vascular endothelial growth factor drugs, or anti-VEGF drugs, has revolutionized the treatment of wet AMD. Less often, laser surgery may be used. Another treatment that may help certain people with severe, end-stage AMD is a device called the implantable miniature telescope (see “A tiny telescope inside the eye”).

Anti-VEGF drugs

Vascular endothelial growth factor (VEGF) is a substance that stimulates the growth of new blood vessels. VEGF has been linked to abnormal blood vessel growth and leakage in AMD and other common retinal diseases, such as diabetic retinopathy and retinal venous occlusive disease. Anti-VEGF drugs block the effects of VEGF (see Figure 13), inhibiting the growth of abnormal new blood vessels.

Figure 13: Targets for anti-VEGF therapy

The wet form of age-related macular degeneration injures healthy tissue in the retina. The blood vessels and photoreceptor cells of a healthy eye are seen in the top illustration (A). When VEGF molecules stimulate abnormal blood vessel development, healthy blood vessels sprout tentacles that extend under and into the retina, often involving the macula (B).

These new vessels are fragile, often leaking blood and other fluids that injure tissue and photoreceptor cells. Anti-VEGF drugs counteract the action of VEGF molecules, inhibiting blood vessel proliferation. The drugs also appear to decrease the amount of leakage from abnormal blood vessels.

During anti-VEGF treatments, the doctor first numbs your eye and then injects the drug into your eyeball with a very fine needle. Most people who receive the injection say it either doesn’t hurt or it causes mild to moderate discomfort that feels a bit like touching their eye in search of a lost contact lens. You will need injections at regular intervals for several months to several years. Possible side effects include short-term eye pain, irritation, discharge, and seeing spots or floaters, but these are often mild. More serious side effects, including infections that can lead to vision loss, occur in less than one in 2,000 to 3,000 injections.

Three anti-VEGF drugs are FDA-approved for treating wet AMD. Doctors rarely prescribe the oldest one, pegaptanib (Macugen) because the newer drugs—ranibizumab (Lucentis) and aflibercept (Eylea)—are far more effective. A fourth drug, bevacizumab (Avastin), is FDA-approved for treating several types of cancer, but it has long been used “off-label” to treat AMD.

Most research suggests that ranibizumab, aflibercept, and bevacizumab are all highly effective for AMD. Bevacizumab and ranibizumab have gone head-to-head in a number of studies, and the two drugs appear to work equally well for stabilizing or improving visual acuity. In one trial, both drugs improved vision when given either monthly or on an as-needed basis, although monthly treatments led to greater vision improvement. For some people, one drug might work better than another.

The main difference between these drugs is the cost, which runs about $50 per dose for bevacizumab versus about $2,000 per dose for ranibizumab and $1,900 for aflibercept. Because anti-VEGF drugs can be expensive, check your insurance plan or Medicare coverage to see how much of the cost you will need to shoulder (if any) if you choose this therapy.


Laser treatments

Because anti-VEGF drugs have become the treatment of choice for many people with wet AMD, laser treatments are not often used today. Laser surgery has been supplanted for two reasons: it often fails to prevent the growth of new blood vessels, and it destroys both diseased sections of the retina and adjacent healthy ones. Moreover, laser surgery does nothing to correct or slow the underlying disease process in wet AMD.

In general, lasers are used only in situations where the leaking blood vessels are relatively small and located far from the central portion of the macula, or when someone cannot have intraocular injections because of an eye infection or advanced glaucoma. Few people fall into these categories.

When laser surgery is performed, the following treatments can be used.

Laser photocoagulation. In this procedure, the doctor aims a laser at leaky blood vessels to seal them and prevent further see page. People reap the most benefits when the procedure is done on newly formed vessels that haven’t yet encroached on the fovea­—­though such cases are rare, as most people with wet AMD already have blood vessels adjacent to or under the fovea. In people who qualify for the procedure, sealing off the leaking blood vessels may restore vision. Laser photocoagulation can be done in a doctor’s office and takes only a few minutes, although the entire office visit may take significantly longer, and sometimes multiple treatments are necessary. You may experience some mild discomfort and sensitivity to light afterward. Frequent checkups will be scheduled, during which the doctor may repeat the fluorescein angiography test to assess the status of the blood vessels. The surgery is often helpful, but in about half the cases, the condition recurs and may require more laser treatments.

Photodynamic therapy. Another option is photodynamic therapy, which uses a laser in combination with the light-activated drug verteporfin (Visudyne) to treat wet AMD. The procedure is a two-step, 15-minute process that can be done in a doctor’s office. First, the drug is injected into a vein in the arm through an intravenous line over a 10-minute period. During the next five minutes, the drug travels through the body and accumulates in the abnormal blood vessels in the eye. The doctor then activates the drug by shining a low-intensity laser into the eye for about 90 seconds. This produces a highly energized form of oxygen that kills abnormally growing cells, closing off the abnormal blood vessels without damaging surrounding healthy eye tissue. Visudyne therapy alone rarely restores vision; more often, it simply slows retinal damage and vision loss. To preserve vision, people usually need more than one Visudyne treatment per year, as recurrences are common.

For people who don’t get good results from anti-VEGF drugs, doctors sometimes add photodynamic therapy and steroid injections to the anti-VEGF drug regimen. However, studies have not found that this combination treatment is any more effective than anti-VEGF drugs alone.

If you undergo Visudyne therapy, you’ll need to avoid exposing your skin or eyes to direct sunlight or bright light for two to five days after treatment. Your eyes may be especially sensitive to light. Speak to your eye doctor about other steps you’ll need to take following this therapy.

On the horizon

Current AMD treatments target the proliferating leaky blood vessels that are the hallmark of AMD. These treatments, while effective, require frequent injections—often every four to eight weeks. These injections can be expensive and time-consuming, and they can have side effects. Pioneering new therapies aim to protect vision without the need for such injections. At the forefront of AMD research are two breakthrough technologies: gene therapy and stem cell therapy.

Gene therapy for AMD involves introducing a new gene into the body to control blood vessel growth and improve vision. One technique under investigation uses a virus to carry specific DNA into the retina. Once in place, the new DNA codes for the production of a protein that stops abnormal blood vessel growth. The body then continues producing this protein long-term, minimizing or eliminating the need for repeated anti-VEGF drug injections. A similar treatment has already been successfully used to treat one type of childhood retinal disease, and doctors hope it will also work for AMD.

Another avenue of research aims to replace damaged retinal cells using stem cells—fledgling cells that can develop into many different kinds of cells, including those of the retina. Researchers are examining the potential of embryonic stem cells to replace damaged retinal pigment epithelial (RPE) cells, which are essential for a healthy retina. Once implanted, stem cells can also release substances called trophic factors, which help the damaged tissue heal and restore itself. However, stem cell therapy is considered controversial because embryonic stem cells are taken from unimplanted human embryos. Also, there is concern that the stem cells might replicate uncontrollably, potentially leading to the development of cancer. So far, research has not shown evidence of this risk. Both gene therapy and stem cell research for AMD are promising, but still preliminary.

A tiny telescope inside the eye

A telescopic lens the size of a pea that is surgically placed within the eye may help older people with severe AMD see more clearly. The implantable miniature telescope (IMT) functions like a telephoto lens on a camera, magnifying images by two to three times. The telephoto effect allows images in the central visual field (so-called straight-ahead vision) to focus not on the damaged macula but instead on other, healthier areas of the retina. By reducing the “blind spot” that results from severe AMD, the implant enables people to recognize images that had been either difficult or impossible for them to see.

The IMT is designed to go in one eye only, for jobs like reading and recognizing faces. The other eye is used for peripheral vision during activities such as walking. People who receive the IMT must participate in a structured vision rehabilitation program to learn how to use their new eyesight. In a study of 206 people who received the IMT, 67% of the treated eyes had an improvement of three lines or greater on an eye chart, compared with 13% of the non-implanted control eyes.

The device, which was approved by the FDA in 2010, costs about $15,000, which doesn’t include the surgery used to implant it. Medicare will cover the cost for eligible patients, but this device isn’t appropriate for everyone with AMD. To be considered for the implant, you must

  • be at least 65 years old

  • have irreversible, end-stage AMD in both eyes (either dry or wet AMD)

  • have vision between 20/160 and 20/800

  • have been unsuccessful with other AMD treatments

  • show improvement on a vision chart when you use an external telescope

  • have not had cataract surgery in the eye in which the
    telescope will be implanted.



Self-care

Although AMD cannot be cured, early detection is important to prevent further deterioration of the retina. For this reason, it’s crucial that older people have regular eye exams and contact their doctors about any changes in their eye health and vision. Because all the available treatments for wet AMD work best in the disease’s early stages, consult an ophthalmologist immediately if you notice symptoms.

Home monitoring. People who are already diagnosed with AMD can monitor their condition by testing themselves at home with an Amsler grid (see Figure 12) or the ForeseeHome monitor (see “Monitoring AMD”). Keep the Amsler grid on the refrigerator door or another convenient spot. By routinely testing each eye, someone with dry AMD may be warned that wet AMD is beginning, while people who have already had laser surgery for AMD may be alerted to leakage or bleeding.

If you have already lost some of your vision to AMD, low-vision aids can help maximize the sight you have left (see “Living with low vision”). Specialists in low vision can prescribe appropriate aids and provide referrals to agencies that offer support and assistance to the visually impaired.


Preventing and slowing AMD

While there is no surefire way to prevent AMD, you can take steps that may delay onset of the disease or reduce its severity. Because smoking can accelerate AMD damage, quitting smoking is an important preventive step. Wearing hats and sunglasses that block the sun’s blue wavelengths—which are thought to possibly promote AMD—may also provide protection.

Evidence also suggests that certain nutrients help prevent macular degeneration. Middle-aged and older people may benefit from diets with plenty of fresh fruits and dark green leafy vegetables—such as spinach, collard greens, and kale—that are rich in lutein and zeaxanthin. For people at high risk of developing the advanced stages of wet AMD, high-dose combinations of antioxidant vitamins and minerals may lower their risk by about 25%. Supplements don’t seem to benefit people who either do not have AMD or who have early AMD. Ask your doctor about taking antioxidant-zinc supplements if you have intermediate or advanced dry AMD or wet AMD. The omega-3s tested in AREDS2 also didn’t seem to have a benefit for slowing AMD progression, but eating fish and other foods high in these nutrients may still be worthwhile for preserving optimal vision and overall good health.



Diabetic retinopathy

With cases of diabetes escalating, the eye problem known as diabetic retinopathy is a serious public health issue. In fact, it’s the leading cause of new blindness cases in adults. Nearly eight million Americans live with diabetic retinopathy, and their vision is at risk.

Diabetes comes in two main forms: type 1 and type 2. Type 1 diabetes is an autoimmune disease, in which the body’s own immune system damages the pancreas so that it is unable to produce insulin, the hormone that enables sugar and other nutrients to enter cells for energy and growth. Type 2 diabetes occurs when the body becomes resistant to the effects of insulin. Both disorders lead to high blood sugar levels that, if left untreated, have serious long-term consequences throughout the body, including the eyes.

People with diabetes are at greater risk of developing cataracts and glaucoma, but a third problem—diabetic retinopathy—is most likely to cause severe vision loss and even blindness. Diabetic retinopathy occurs when abnormal blood sugar levels damage small blood vessels in the retina.

Diabetic retinopathy occurs in two stages. First, the walls of the small blood vessels become abnormal and weaken. They leak fluid into the surrounding tissue, often leaving deposits of protein and fat called hard exudates. The vessels also develop microaneurysms, tiny bulges or balloons in their walls that tend to leak red blood cells and plasma into the retina. As the condition progresses, the abnormal vessels begin to close, robbing the retina of its blood supply. Nerve fibers die off because of poor circulation and a lack of oxygen, creating white cottony patches known as soft exudates or cotton-wool spots (see Figure 14).

Figure 14: Diabetic retinopathy

Ongoing high blood sugar levels that result from poorly managed diabetes can cause the tiny blood vessels in the retina to break down and leak fluid into surrounding tissues, leaving deposits of protein and fat called hard exudates. The vessel walls can also develop tiny bulges called microaneurysms. Eventually, the damage blocks the retina’s blood supply. Nerve fibers die, creating white fluffy patches known as cotton-wool spots or soft exudates.

These changes may not necessarily alter your vision. But if the fluid or blood leakage occurs near the macula—the part of the retina responsible for sharp, central vision—your sight will be impaired (see Figure 15). When fluid leaks into the center of the macula, the macula can swell, blurring vision. This condition, known as macular edema, can range from minimal to severe.

Figure 15: Diabetic retinopathy vision

As diabetic retinopathy progresses, you may notice spots and floaters in your vision. Central vision may become distorted.

Photo courtesy of the National Eye Institute.

As retinopathy advances, the decreased blood flow causes the damaged retina to try to repair itself by sprouting new blood vessels. However, these new vessels grow abnormally and extend into the vitreous humor, the gel-filled compartment in front of the retina. The fragile new vessels are prone to leak blood and break. When they bleed into the vitreous humor, they can block the passage of light and cause a sudden loss of vision. The blood is usually reabsorbed, but scar tissue may form. The scar tissue tugs on the retina, pulling it away from the back of the eye, which can lead to permanent vision loss (see “Retinal tear or detachment”). In some cases, the blood does not reabsorb, and surgery may be required to remove the blood and treat the underlying retinopathy.

Symptoms of diabetic retinopathy

  • Blurred vision

  • Fluctuating vision

  • Distorted vision

  • Floating spots

Preventing diabetic retinopathy

One of the best ways to protect your vision if you have diabetes is to control your blood glucose levels carefully. People with diabetes who keep their blood sugar at near-normal levels cut their risk of developing eye diseases and macular edema by 75%. If you have diabetes, also pay careful attention to your blood pressure and cholesterol levels. Levels above normal increase the likelihood that diabetic retinopathy will occur and that it will significantly affect your vision.


Progression of diabetic retinopathy

In the early stages of diabetic retinopathy, there may be no symptoms. But as the problem becomes more severe, macular edema may develop. This can cause a noticeable decline in central vision, especially as the swelling increases. An eye exam can detect even the earliest changes, such as

  • leaking blood vessels

  • retinal swelling (macular edema)

  • fatty deposits on the retina

  • damaged nerve tissue

  • small, balloon-like abnormalities known as microaneurysms.

As diabetic retinopathy progresses to its later stage, symptoms become more dramatic. You might notice spots that are really specks of blood floating in your vision. Although sometimes the specks will clear without treatment, hemorrhaging can occur repeatedly, often while you sleep. Seek treatment immediately from an eye care professional if you notice specks obscuring your vision. Otherwise, bleeding may become more severe, and vision loss and blindness can occur. The sooner you get help, the better, as earlier treatment is more likely to be effective.


Detecting diabetic retinopathy

Unfortunately, diabetic retinopathy has no early warning signs. The best way to protect yourself is to understand your risk and get your vision tested as often as necessary. Anyone with diabetes—either type 1 or type 2—should get a comprehensive dilated eye exam at least once a year. Comprehensive eye exams can detect macular edema and diabetic retinopathy in their earliest stages. Prompt treatment can help prevent severe vision loss and blindness.


Treating diabetic retinopathy

There is no cure for diabetic retinopathy. But you can take steps to prevent vision loss—or at least slow its progression. Treatments include laser therapies, anti-VEGF drugs, and steroids. The choice depends on the type and extent of your retinopathy.

Managing your blood sugar and blood pressure are also important for helping to slow the worsening of eye damage and other complications of diabetes. Three other Harvard Special Health Reports—Diabetes, Healthy Eating for Type 2 Diabetes, and Controlling Your Blood Pressure—provide more information on these topics. (To order, call 877-649-9457, toll-free, or go to www.health.harvard.edu.)

Laser treatments

Focal laser treatment is often used for macular edema. In this procedure, the doctor identifies individual leaking blood vessels and seals them off with the laser. This slows leakage and decreases fluid around the retina. Local anesthetics prevent any discomfort during the procedure, which typically involves 20 to 50 laser burns per eye. If macular edema affects both eyes, you’ll need a second session—usually a week or so later—for the other eye. The procedure can cut the risk of further vision loss in half, and in a small number of people, it actually restores vision.

Another type of laser procedure, known as scatter laser therapy, is used for advanced retinopathy. The doctor makes 1,000 to 1,500 laser burns in the outer edges of the retina, away from the centrally located macula. Because so many laser burns are needed, treatment may require more than one session. This laser treatment may be uncomfortable, so ask your doctor about the possibility of receiving a shot to numb the eye. Scatter laser therapy helps prevent new blood vessel growth. The vessels stop proliferating or even regress, which lowers the risk of hemorrhage or detachment. Possible downsides to this treatment include slight impairments to peripheral vision, color vision, and night vision.

If the bleeding in your eye is severe, the doctor may need to perform a vitrectomy before the laser surgery. The doctor makes several small incisions in your eye and replaces the vitreous humor (which is clouded with blood) with a salt solution or an air or gas bubble. Your eye will be red and sensitive, and you’ll need to use medicated eye drops and wear an eye patch while it heals.


Anti-VEGF drugs

Although laser treatments have been the standard of care for diabetic retinopathy for nearly 30 years, recent research has shown that anti-VEGF drugs—either alone or in combination with laser therapy—may be the best way to prevent vision loss. These drugs, which block a chemical signal that stimulates blood vessel growth, are also used to treat advanced AMD (see “Anti-VEGF drugs”).

In 2012, the FDA approved the anti-VEGF drug ranibizumab (Lucentis) for the treatment of diabetic macular edema. In studies, ranibizumab led to rapid vision improvements, and those gains were sustained for three years. The FDA approved another VEGF drug, aflibercept (Eylea), in 2014. Aflibercept was already approved for wet AMD and macular edema after central retinal vein occlusion (a blockage of the main vein in the retina). A third drug, bevacizumab (Avastin), is FDA-approved for treating several types of cancer, but is also used for diabetic retinopathy. While all three are effective in treating this disease, recent research has shown that aflibercept may be more effective for people whose initial vision is worse.


Steroids

Steroid injections have also been used to treat advanced diabetic retinopathy. Steroids can reduce retinal swelling and often improve vision, at least for a while. The benefits often disappear after one to two years, and there are long-term risks, which include the possible development of cataract or glaucoma.

Two recently approved steroid implants, which gradually release steroids into the eye, prevent the need for regular injections. Dexamethasone intravitreal implant (Ozurdex) is biodegradable, meaning that it dissolves in the eye and never needs to be removed. In a large European study called the Geneva Study, it both reduced the risk of vision loss and led to vision improvement. Plus, this implant appears less likely to cause glaucoma than traditional steroid injections. The other steroid implant, fluocinolone (Iluvien), can continue to work for up to three years.




Living with low vision

Many people must live with vision that limits their daily activities, a condition known as low vision. Macular degeneration is the most common cause of low vision. Low vision may involve blurry vision, poor central vision, loss of peripheral vision, or even double vision. Whatever the symptom, the immediate consequences are often the same—difficulty performing day-to-day activities such as reading a newspaper, using a computer, watching television, cooking a meal, or crossing the street. Although you may not be able to cure low vision, you often can find ways to cope with it.

Magnification tools. The magnifying lens remains one of the most common tools to help compensate for low vision. Most magnifying lenses are handheld, but some are mounted in stands. Others can be incorporated into prescription glass lenses to be used for reading or detail work. Special lenses that work like miniature telescopes can also be mounted on a pair of glasses and used for driving or watching a movie. If you have trouble with excessive glare or reduced contrast (less distinction between light and dark), glasses with special filters or stand-mounted magnifiers containing a light source may help. An expensive option is a device similar to something once featured in Star Trek: goggles consisting of two tiny high-definition television sets that display images recorded and enhanced by a digital camcorder. You may need to invest some time and effort to learn how to use these devices properly.


Computer aids. Many software programs can make the text on a computer monitor larger or more readable. Options include programs that enable you to change font size and background displays, and specialized text-to-speech conversion programs that read text aloud. Separate devices—such as special keyboards or monitor magnifiers—are also available. Most major computer supply stores carry these products.

Reading aids. If you have trouble discerning text, you can buy any number of assistive products. Inexpensive, low-tech vision aids include large-print versions of address books, checks, utility bills, playing cards, and telephones. “Talking” watches, alarm clocks, pillboxes, and calculators allow you to hear, rather than see, numbers and words. Video magnifiers project the words from a book or other reading material onto a large screen.

If you have trouble reading books and newspapers, consider buying large-print versions. Or, purchase an e-reader like the Kindle Paperwhite, which both improves contrast and provides a light source to increase readability and reduce eyestrain. If you have trouble reading books, audiobooks are another option. You can order these and other low-vision devices through several organizations, including the Low Vision Center (see “Resources”).

Improved lighting. By age 60, your retina requires three times as much light as it did when you were 20. One very easy way to enhance your vision is to improve the lighting in your home. Use compact fluorescent light bulbs of 15 watts or more, or incandescent bulbs of at least 60 watts. Position lamps so that the light shines from behind you, directly onto the materials in front of you, rather than from high above you.

Rehabilitation. In addition to using various gadgets, people with low vision can learn a few simple tactics to compensate for their diminished sight and make the home safer.

  • Arrange furniture so you have a clear path to walk, and reduce clutter in your home to prevent falls.

  • Remove or tape down throw rugs.

  • Buy plates and cups in colors that contrast with your tablecloth or placemats.

  • Label your foods and medications with large print to make them easier to identify.

Ophthalmologists, optometrists, and occupational therapists can help you learn these and other techniques.

Whatever your vision problem, there are now more ways to cope than ever before. But remember, whatever your age, the single most important step you can take to preserve your vision is simply to have your eyes checked regularly and to follow your doctor’s recommendations. By following these simple steps, you can prevent a great deal of damage and safeguard this precious sense as you age.

Vision apps for low vision and other eye problems

Over the past decade, cellphones have evolved from devices that can simply make calls to ones that can let us check email, surf the Internet, schedule our day, and even keep us healthier. A few free or low-cost apps for the iPhone and Android are specifically designed to promote eye health.

Big Clock. If you struggle to see the numbers on your clock, this large-numbered phone app makes it much easier for you to tell time.

Eye Drops. This free app reminds you when to take your glaucoma medications. It even lets you take a photo of the bottle, so you’ll know exactly which medicine you need.

EyeXam. This app lets you test your vision, which can help you determine whether it’s time for a checkup with your ophthalmologist. EyeXam also will help you locate an eye doctor in your area and schedule an appointment.

iRead. Designed by an ophthalmologist, iRead turns your iPhone into a light, making it easier to read menus in dimly lit restaurants or programs in dark theaters.

MaculaTester. This interactive version of the Amsler grid not only helps you identify vision changes that can signal macular degeneration or retinopathy, but also allows you to record the area where you notice distortion so you can share the information with your ophthalmologist.

Magnifying Glass. Download this app and point your phone at a book, menu, or other hard-to-read material and it will instantly magnify the text for you. The iPhone version also includes a light.

Vision Sim. This app simulates vision through the eyes of someone with macular degeneration, glaucoma, diabetic retinopathy, or other common eye diseases, so you can see what might happen if you don’t take the appropriate steps to care for your sight.


Resources

Association for Macular Diseases

210 E. 64th St., 8th Floor
New York, NY 10065
212-605-3719
www.macula.org

This organization provides information and support for people with macular degeneration and other macular diseases.

EyeCare America

P.O. Box 429098
San Francisco, CA 94142
877-887-6327 (toll-free)
www.eyecareamerica.org

Seniors EyeCare Program

800-222-EYES (800-222-3937) (toll-free)

This program of the American Academy of Ophthalmology seeks to raise awareness about eye diseases and ensure that everyone has access to medical eye care. It includes a Seniors EyeCare Program for older adults. The website also offers an online referral center that can help you determine whether you qualify for a free eye exam.

Eye Surgery Education Council

4000 Legato Road, Suite 700
Fairfax, VA 22033
703-591-2220
www.eyesurgeryeducation.org

Established by the American Society of Cataract and Refractive Surgery, the Eye Surgery Education Council provides information on a variety of common vision problems and therapies.

Glaucoma Research Foundation

251 Post St., Suite 600
San Francisco, CA 94108
800-826-6693 (toll-free)
www.glaucoma.org

This foundation provides educational materials on glaucoma and publishes a free newsletter, Gleams, three times a year.

Lighthouse International

111 E. 59th St.
New York, NY 10022
800-284-4422 (toll-free)
www.lighthouse.org

Lighthouse provides educational materials on age-related vision problems and offers referrals to vision and rehabilitation agencies. Call for a catalog of aids for daily living.

Low Vision Center

4905 Del Ray Ave., Suite 504
Bethesda, MD 20814
301-951-4444
www.lowvisioninfo.org

The center offers information to help people with limited vision remain independent and lead fuller lives.

National Eye Institute

Information Office
31 Center Drive, MSC 2510
Bethesda, MD 20892
301-496-5248
www.nei.nih.gov

Part of the National Institutes of Health, the National Eye Institute provides up-to-date information on eye diseases and research.

Prevent Blindness America

211 W. Wacker Drive, Suite 1700
Chicago, IL 60606
800-331-2020 (toll-free)
www.preventblindness.org

Prevent Blindness America provides fact sheets, brochures, and other informational material on eye safety, eye care, vision screening, and eye ailments.


Glossary

accommodation: The ability of the eye’s lens to focus at a range of distances.

anterior chamber: The space behind the cornea and in front of the iris; it is filled with aqueous humor.

aqueous humor: The watery fluid that nourishes the eye and fills the anterior and posterior chambers.

astigmatism: A refractive error characterized by irregular curvature of the cornea, causing distorted images.

cones: Specialized cells in the retina that are sensitive to color and light; they are more active in light than in darkness, provide sharp vision, and are abundant in the macular area of the retina.

conjunctiva: The transparent membrane that lines the eyelid and covers the front portion of the sclera.

cornea: The curved, transparent dome of tissue at the front of the eye, through which light first passes on its way into the eye.

drusen: Tiny yellow deposits that form beneath the macula and may indicate early stages of age-related macular degeneration.

fluorescein angiography: A diagnostic test that photographs blood vessels in the retina after the intravenous injection of a special dye.

fovea: A pitlike area in the middle of the macula that provides the clearest vision.

hyperopia: An optical error in which light rays reach the retina before converging at a focal point; commonly known as farsightedness.

intraocular lens: A small artificial lens permanently fixed inside the eye to replace the natural lens during cataract surgery.

iris: The colored ring in front of the lens that controls the size of the pupil and how much light enters the eye.

lacrimal gland: The gland that produces tears. It is located in the upper, outer section of the eye’s orbit.

lens: A flexible, transparent structure directly behind the iris that focuses rays of light onto the retina.

macula: The area of the retina packed with cones, which is responsible for sharp central vision.

miotic: A type of eye drop that constricts the pupil. It treats glaucoma by improving the capacity of the eye’s drainage system.

myopia: An optical error in which light rays meet and focus before reaching the retina; also known as nearsightedness.

ophthalmoscope: An instrument with a light and mirrors for examining the deep interior of the eye.

optic nerve: A “cable” that emanates from the back of the eye, consisting of specialized nerve fibers that transmit visual impulses to the brain.

orbit: The bony socket that surrounds the eyeball.

peripheral vision: Side vision, or what the eye perceives outside the direct line of vision.

posterior chamber: The area behind the iris and in front of the lens that is filled with aqueous humor.

retina: The innermost layer of the eye, consisting of specialized cells and lining nearly three-quarters of the back of the eye. It converts light energy to electrical energy and sends visual images to the brain via the optic nerve.

retinal vein occlusion: A blockage in the small veins that transport blood away from the retina.

rods: Light-sensitive cells in the retina that respond best in darkness and dim light.

sclera: The white of the eye. This tough, protective coating of collagen and elastic tissue, together with the cornea, makes up the outer layer of the eyeball.

slit lamp: An instrument that magnifies internal structures of the eye with the aid of a beam of light directed through a narrow slit.

tonometry: A glaucoma screening test that measures pressure inside the eye.

visual acuity: The eye’s ability to see sharply. Acuity is usually measured in comparison with what a normal eye would see from 20 feet.

visual field: The scope of what the eye sees, including central and peripheral vision.

vitreous humor: The clear, gel-like substance that fills the space behind the lens and supports the shape of the rear portion of the eye.


Credits

Medical Editor
Laura C. Fine, MD

Clinical Instructor in Ophthalmology,
Harvard Medical School
Glaucoma and Cataract Specialist,
Ophthalmic Consultants of Boston

Jeffrey S. Heier, MD

Clinical Instructor in Ophthalmology,
Harvard Medical School
Director, Vitreoretinal Service,
Ophthalmic Consultants of Boston

Executive Editor
Anne Underwood

Writer
Stephanie Watson, Julie Corliss

Copy Editor
Robin Netherton

Creative Director
Judi Crouse

Production Manager
Lori Wendin

Illustrators
Harriet Greenfield, Scott Leighton

Published by Harvard Medical School
Gregory D. Curfman, MD, Editor in Chief
Patrick J. Skerrett, Executive Editor

In association with Belvoir Media Group, LLC
Robert Englander, Chairman and CEO
Timothy H. Cole, Executive Vice President and Editorial Director

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