Eye Disorders

Section 17.1: Cataracts

This section includes text excerpted from “Facts about Cataract,” National Eye Institute (NEI), September 2015.

What Is a Cataract?

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery. A cataract can occur in either or both eyes. It cannot spread from one eye to the other.

What Is the Lens?

The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye. In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain. The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image you see will be blurred.

 


Figure 17.1. Eye





Figure 17.1. Eye
What Causes Cataracts?

The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.

But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see. Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.

How Do Cataracts Affect Vision?

Age-related cataracts can affect your vision in two ways:

Who Is at Risk for Cataract?

The risk of cataract increases as you get older. Other risk factors for cataract include:

What Are the Symptoms of a Cataract?

The most common symptoms of a cataract are:

These symptoms also can be a sign of other eye problems. If you have any of these symptoms, check with your eye care professional.

How Is a Cataract Treated?

The symptoms of early cataract may be improved with new eyeglasses, brighter lighting, antiglare sunglasses, or magnifying lenses. If these measures do not help, surgery is the only effective treatment. Surgery involves removing the cloudy lens and replacing it with an artificial lens.

Sometimes a cataract should be removed even if it does not cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration (AMD) or diabetic retinopathy.

If you choose surgery, your eye care professional may refer you to a specialist to remove the cataract. If you have cataracts in both eyes that require surgery, the surgery will be performed on each eye at separate times, usually four weeks apart.

Is Cataract Surgery Effective?

Cataract removal is one of the most common operations performed in the United States. It also is one of the safest and most effective types of surgery. In about 90 percent of cases, people who have cataract surgery have better vision afterward.

What Are the Risks of Cataract Surgery?

As with any surgery, cataract surgery poses risks, such as infection and bleeding. Before cataract surgery, your doctor may ask you to temporarily stop taking certain medications that increase the risk of bleeding during surgery. After surgery, you must keep your eye clean, wash your hands before touching your eye, and use the prescribed medications to help minimize the risk of infection. Serious infection can result in loss of vision.

What If I Have Other Eye Conditions and Need Cataract Surgery?

Many people who need cataract surgery also have other eye conditions, such as age-related macular degeneration or glaucoma. If you have other eye conditions in addition to cataract, talk with your doctor. Learn about the risks, benefits, alternatives, and expected results of cataract surgery.

When Will My Vision Be Normal Again?

You can return quickly to many everyday activities, but your vision may be blurry. The healing eye needs time to adjust so that it can focus properly with the other eye, especially if the other eye has a cataract. Ask your doctor when you can resume driving. If you received an IOL (intraocular lens), you may notice that colors are very bright. The IOL is clear, unlike your natural lens that may have had a yellowish/ brownish tint. Within a few months after receiving an IOL, you will become used to improved color vision. Also, when your eye heals, you may need new glasses or contact lenses.

What Can I Do If I Already Have Lost Some Vision from Cataract?

If you have lost some vision, speak with your surgeon about options that may help you make the most of your remaining vision.

What Can I Do to Protect My Vision?

Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataract. If you smoke, stop. Researchers also believe good nutrition can help reduce the risk of age-related cataract. They recommend eating green leafy vegetables, fruit, and other foods with antioxidants. If you are age 60 or older, you should have a comprehensive dilated eye exam at least once every two years. In addition to cataract, your eye care professional can check for signs of age-related macular degeneration, glaucoma, and other vision disorders. Early treatment for many eye diseases may save your sight.

Section 17.2: Corneal Diseases and Conditions

This section includes text excerpted from “Facts about the Cornea and Corneal Disease,” National Eye Institute (NEI), May 2016.

What Is the Cornea?

The cornea is the eye's outermost layer. It is the clear, dome-shaped surface that covers the front of the eye. It plays an important role in focusing your vision.

Why Are Tears Important to the Cornea?

Every time we blink, tears are distributed across the cornea to keep the eye moist, help wounds heal, and protect against infection. Tears form in three layers:

What Are Some Common Conditions That Affect the Cornea?

Injuries

After minor injuries or scratches, the cornea usually heals on its own. Deeper injuries can cause corneal scarring, resulting in a haze on the cornea that impairs vision. If you have a deep injury, or a corneal disease or disorder, you could experience:

If you experience any of these symptoms, seek help from an eye care professional.

Allergies

The most common allergies that affect the eye are those related to pollen, particularly when the weather is warm and dry. Symptoms in the eye include redness, itching, tearing, burning, stinging, and watery discharge, although usually not severe enough to require medical attention. Antihistamine decongestant eye drops effectively reduce these symptoms. Rain and cooler weather, which decreases the amount of pollen in the air, can also provide relief.

Keratitis

Keratitis is an inflammation of the cornea. Noninfectious keratitis can be caused by a minor injury, or from wearing contact lenses too long. Infection is the most common cause of keratitis. Infectious keratitis can be caused by bacteria, viruses, fungi or parasites. Often, these infections are also related to contact lens wear, especially improper cleaning of contact lenses or overuse of old contact lenses that should be discarded. Minor corneal infections are usually treated with antibacterial eye drops. If the problem is severe, it may require more intensive antibiotic or antifungal treatment to eliminate the infection, as well as steroid eye drops to reduce inflammation.

What Are Corneal Dystrophies?

A corneal dystrophy is a condition in which one or more parts of the cornea lose their normal clarity due to a build-up of material that clouds the cornea. These diseases:

Corneal dystrophies affect vision in different ways. Some cause severe visual impairment, while a few cause no vision problems and are only discovered during a routine eye exam. Other dystrophies may cause repeated episodes of pain without leading to permanent vision loss. Some of the most common corneal dystrophies include keratoconus, Fuchs dystrophy, lattice dystrophy, and map—dot—fingerprint dystrophy.

Fuchs Dystrophy

Fuchs dystrophy is a slowly progressing disease that usually affects both eyes and is slightly more common in women than in men. It can cause your vision to gradually worsen over many years, but most people with Fuchs dystrophy won't notice vision problems until they reach their 50s or 60s.

Fuchs dystrophy is caused by the gradual deterioration of cells in the corneal endothelium; the causes aren't well understood. Normally, these endothelial cells maintain a healthy balance of fluids within the cornea. Healthy endothelial cells prevent the cornea from swelling and keep the cornea clear. In Fuchs dystrophy, the endothelial cells slowly die off and cause fluid buildup and swelling within the cornea. The cornea thickens and vision becomes blurred.

As the disease progresses, Fuchs dystrophy symptoms usually affect both eyes and include:

The first step in treating Fuchs dystrophy is to reduce the swelling with drops, ointments, or soft contact lenses. If you have severe disease, your eye care professional may suggest a corneal transplant.

Map—Dot—Fingerprint Dystrophy

Symptoms include blurred vision, pain in the morning that lessens during the day, sensitivity to light, excessive tearing, and a feeling that there's something in the eye.

Map—dot—fingerprint dystrophy usually occurs in both eyes and affects adults between the ages of 40 and 70, although it can develop earlier in life. Typically, map—dot—fingerprint dystrophy will flare up now and then over the course of several years and then go away, without vision loss. Some people can have map-dot-fingerprint dystrophy but not experience any symptoms.

Others with the disease will develop recurring epithelial erosions, in which the epithelium's outermost layer rises slightly, exposing a small gap between the outermost layer and the rest of the cornea. These erosions alter the cornea's normal curvature and cause blurred vision. They may also expose the nerve endings that line the tissue, resulting in moderate to severe pain over several days.

The discomfort of epithelial erosions can be managed with topical lubricating eye drops and ointments. If drops or ointments don't relieve the pain and discomfort, there are outpatient surgeries including:

What Other Diseases Can Affect the Cornea?

Herpes Zoster (Shingles)

Shingles is a reactivation of the varicel-lazoster virus (VZV), the same virus that causes chickenpox. If you have had chickenpox, the virus can live on within your nerve cells for years after the sores have gone away. In some people, the varicel-lazoster virus (VZV) reactivates later in life, travels through the nerve fibers, and emerges in the cornea. If this happens, your eye care professional may prescribe oral antiviral treatment to reduce the risk of inflammation and scarring in the cornea. Shingles can also cause decreased sensitivity in the cornea.

Corneal problems may arise months after the shingles are gone from the rest of the body. If you experience shingles in your eye, or nose, or on your face, it's important to have your eyes examined several months after the shingles have cleared.

Ocular Herpes

Herpes of the eye, or ocular herpes, is a recurrent viral infection that is caused by the herpes simplex virus (HSV-1). This is the same virus that causes cold sores. Ocular herpes can also be caused by the sexually transmitted herpes simplex virus (HSV-2) that causes genital herpes.

Ocular herpes can produce sores on the eyelid or surface of the cornea and over time the inflammation may spread deeper into the cornea and eye, and develop into a more severe infection called stromal keratitis. There is no cure for ocular herpes, but it can be controlled with antiviral drugs.

Glaucoma

ICE is usually present in only one eye. It is caused by the movement of endothelial cells from the cornea to the iris. This loss of cells from the cornea leads to corneal swelling and distortion of the iris and pupil. This cell movement also blocks the fluid outflow channels of the eye, which causes glaucoma.

There is no treatment to stop the progression of ICE, but the glaucoma is treatable. If the cornea becomes so swollen that vision is significantly impaired, a corneal transplant may be necessary.

Pterygium

A pterygium is a pinkish, triangular tissue growth on the cornea. Some pterygia (plural for pyterygium) grow slowly throughout a lifetime, while others stop growing. A pterygium rarely grows so large that it covers the pupil of the eye.

Pterygia are more common in sunny climates and in adults 20–40 years of age. It's unclear what causes pterygia. However, since people who develop pterygia usually have spent significant time outdoors, researchers believe chronic exposure to UV light from the sun may be a factor.

To protect yourself from developing pterygia, wear sunglasses, or a wide-brimmed hat in places where the sunlight is strong. If you have one or more pterygia, lubricating eye drops may be recommended to reduce redness and soothe irritation.

Because a pterygium is visible, some people might want to have it removed for cosmetic reasons. However, unless it affects vision, surgery to remove a pterygium is not recommended. Even if it is surgically removed, a pterygium may grow back, particularly if removed before age 40.

What Treatments Are There for Advanced Corneal Disease?

Laser Surgery

Phototherapeutic keratectomy (PTK) is a surgical technique that uses UV light and laser technology to reshape and restore the cornea. PTK has been used to treat recurrent erosions and corneal dystrophies, such as map-dot-fingerprint dystrophy and basal membrane dystrophy. PTK helps delay or postpone corneal grafting or replacement.

Section 17.3: Dry Eye

This section includes text excerpted from “Facts about Dry Eye,” National Eye Institute (NEI), July 2017.

What Is Dry Eye?

Dry eye occurs when the quantity and/or quality of tears fails to keep the surface of the eye adequately lubricated. Experts estimate that dry eye affects millions of adults in the United States. The risk of developing dry eye increases with advancing age. Women have a higher prevalence of dry eye compared with men.

What Are the Symptoms of Dry Eye? What Are Tears and How Do They Relate to Dry Eye?

In a healthy eye, lubricating tears called basal tears continuously bathe the cornea, the clear, dome-shaped outer surface of the eye. With every blink of the eye, basal tears flow across the cornea, nourishing its cells and providing a layer of liquid protection from the environment. When the glands nearby each eye fail to produce enough basal tears, or when the composition of the tears changes, the health of the eye and vision are compromised. Vision may be affected because tears on the surface of the eye play an important role in focusing light.

Tears are a complex mixture of fatty oils, water, mucus, and more than 1500 different proteins that keep the surface of the eye smooth and protected from the environment, irritants, and infectious pathogens. Tears form in three layers:

What Causes Dry Eye?

Dry eye can occur when basal tear production decreases, tear evaporation increases, or tear composition is imbalanced. Factors that can contribute to dry eye include the following:

How Is Dry Eye Diagnosed and Treated?

People experiencing dry eye symptoms should consult an eye care professional to determine the cause, which guides treatment strategy.

Change medications. Consult a physician about switching medications to alternative ones that are not associated with dry eye. This may alleviate dry eye symptoms.

Over-the-counter (OTC) topical medications. Mild dry eye symptoms may be treated with over-the-counter medications such as artificial tears, gels, and ointments.

Environmental and lifestyle changes. Cutting back on-screen time and taking periodic eye breaks may help. Closing the eyes for a few minutes, or blinking repeatedly for a few seconds, may replenish basal tears and spread them more evenly across the eye. Sunglasses that wrap around the face and have side shields that block wind and dry air can reduce symptoms in windy or dry conditions. In cases of Meibomian gland dysfunction, warm lid compresses and scrubs may be helpful. Smoking cessation and limiting exposure to second-hand smoke also may help.

Devices. FDA-approved devices provide temporary relief from dry eye by stimulating glands and nerves associated with tear production.

Surgical options. Punctal plugs made of silicone or collagen may be inserted by an eye care professional to partially or completely plug the tear ducts at the inner corners of the eye to keep tears from draining from the eye. In severe cases, surgical closure of the drainage ducts by thermal punctal cautery may be recommended to close the tear ducts permanently.

Section 17.4: Glaucoma

This section includes text excerpted from “Healthy Living—Don't Let Glaucoma Steal Your Sight!” Centers for Disease Control and Prevention (CDC), January 11, 2017.

Know the Facts Know Your Risk

Anyone can get glaucoma, but certain groups are at higher risk. These groups include African Americans over age 40, all people over age 60, people with a family history of glaucoma, and people who have diabetes. African Americans are 6 to 8 times more likely to get glaucoma than whites. People with diabetes are 2 times more likely to get glaucoma than people without diabetes.

Take Action

There are many steps you can take to help protect your eyes and lower your risk of vision loss from glaucoma.

Manage and Treat

Vision loss from glaucoma usually affects peripheral vision (what you can see on the side of your head when looking ahead) first. Later, it will affect your central vision, which is needed for seeing objects clearly and for common daily tasks like reading and driving.

Section 17.5: Low Vision

This section includes text excerpted from “Low Vision—What You Should Know,” National Eye Institute (NEI), January 24, 2013. Reviewed September 2017.

What Is Low Vision?

When you have low vision, eyeglasses, contact lenses, medicine, or surgery may not help. Activities like reading, shopping, cooking, writing, and watching TV may be hard to do.

In fact, millions of Americans lose some of their sight every year. While vision loss can affect anyone at any age, low vision is most common for those over age 65.

Low vision is usually caused by eye diseases or health conditions. Some of these include age-related macular degeneration (AMD), cataract, diabetes, and glaucoma. Eye injuries and birth defects are some other causes. Whatever the cause, lost vision cannot be restored. It can, however, be managed with proper treatment and vision rehabilitation.

You should visit an eye care professional if you experience any changes to your eyesight.

How Do I Know If I Have Low Vision?

Below are some signs of low vision. Even when wearing your glasses or contact lenses, do you still have difficulty with—

These could all be early warning signs of vision loss or eye disease. The sooner vision loss or eye disease is detected by an eye care professional, the greater your chances of keeping your remaining vision.

How Do I Know When to Get an Eye Exam?

Visit your eye care professional regularly for a comprehensive dilated eye exam. However, if you notice changes to your eyes or eyesight, visit your eye care professional right away!

What Can I Do If I Have Low Vision?

To cope with vision loss, you must first have an excellent support team. This team should include you, your primary eye care professional, and an optometrist or ophthalmologist specializing in low vision.

Occupational therapists, orientation and mobility specialists, certified low vision therapists, counselors, and social workers are also available to help.

Together, the low vision team can help you make the most of your remaining vision and maintain your independence.

Second, talk with your eye care professional about your vision problems. Even though it may be difficult, ask for help. Find out where you can get more information about support services and adaptive devices. Also, find out which services and devices are best for you and which will give you the most independence.

Third, ask about vision rehabilitation, even if your eye care professional says that “nothing more can be done for your vision.”

Vision rehabilitation programs offer a wide range of services, including training for magnifying and adaptive devices, ways to complete daily living skills safely and independently, guidance on modifying your home, and information on where to locate resources and support to help you cope with your vision loss.

Medicare may cover part or all of a patient's occupational therapy, but the therapy must be ordered by a doctor and provided by a Medicare-approved healthcare provider. To see if you are eligible for Medicare-funded occupational therapy, call 800-633-4227 (800-MEDICARE).

Finally, be persistent. Remember that you are your best healthcare advocate. Explore your options, learn as much as you can, and keep asking questions about vision rehabilitation. In fact, write down questions to ask your doctor before your exam, and bring along a notepad to jot down answers.

There are many resources to help people with low vision, and many of these programs, devices, and technologies can help you maintain your normal, everyday way of life.

What Questions Should I Ask My Eye Care Team?

An important part of any doctor patient relationship is effective communication. Here are some questions to ask your eye care professional or specialist in low vision to jumpstart the discussion about vision loss.

Questions to Ask Your Eye Care Professional Questions to Ask Your Specialist in Low Vision

Section 17.6: Macular Degeneration

This section includes text excerpted from “Facts about Age-Related Macular Degeneration,” National Eye Institute (NEI), September 2015.

What Is Age-Related Macular Degeneration (AMD)?

AMD is a common eye condition and a leading cause of vision loss among people age 50 and older. It causes damage to the macula, a small spot near the center of the retina and the part of the eye needed for sharp, central vision, which lets us see objects that are straight ahead.

In some people, AMD advances so slowly that vision loss does not occur for a long time. In others, the disease progresses faster and may lead to a loss of vision in one or both eyes. As AMD progresses, a blurred area near the center of vision is a common symptom. Over time, the blurred area may grow larger or you may develop blank spots in your central vision. Objects also may not appear to be as bright as they used to be.

AMD by itself does not lead to complete blindness, with no ability to see. However, the loss of central vision in AMD can interfere with simple everyday activities, such as the ability to see faces, drive, read, write, or do close work, such as cooking or fixing things around the house.

The Macula

 


Figure 17.2. Parts of the Eye





Figure 17.2. Parts of the Eye
Who Is at Risk?

Age is a major risk factor for AMD. The disease is most likely to occur after age 60, but it can occur earlier. Other risk factors for AMD include:

Does Lifestyle Make a Difference?

Researchers have found links between AMD and some lifestyle choices, such as smoking. You might be able to reduce your risk of AMD or slow its progression by making these healthy choices:

How Is AMD Detected?

The early and intermediate stages of AMD usually start without symptoms. Only a comprehensive dilated eye exam can detect AMD. The eye exam may include the following:

During the exam, your eye care professional will look for drusen, which are yellow deposits beneath the retina. Most people develop some very small drusen as a normal part of aging. The presence of medium-to-large drusen may indicate that you have AMD. Another sign of AMD is the appearance of pigmentary changes under the retina. In addition to the pigmented cells in the iris (the colored part of the eye), there are pigmented cells beneath the retina. As these cells break down and release their pigment, your eye care professional may see dark clumps of released pigment and later, areas that are less pigmented. These changes will not affect your eye color.

What Are the Stages of AMD?

There are three stages of AMD defined in part by the size and number of drusen under the retina. It is possible to have AMD in one eye only, or to have one eye with a later stage of AMD than the other.

AMD has few symptoms in the early stages, so it is important to have your eyes examined regularly. If you are at risk for AMD because of age, family history, lifestyle, or some combination of these factors, you should not wait to experience changes in vision before getting checked for AMD.

Not everyone with early AMD will develop late AMD. For people who have early AMD in one eye and no signs of AMD in the other eye, about five percent will develop advanced AMD after 10 years. For people who have early AMD in both eyes, about 14 percent will develop late AMD in at least one eye after 10 years. With prompt detection of AMD, there are steps you can take to further reduce your risk of vision loss from late AMD.

If you have late AMD in one eye only, you may not notice any changes in your overall vision. With the other eye seeing clearly, you may still be able to drive, read, and see fine details. However, having late AMD in one eye means you are at increased risk for late AMD in your other eye. If you notice distortion or blurred vision, even if it doesn't have much effect on your daily life, consult an eye care professional.

How Is AMD Treated?

Early AMD

Currently, no treatment exists for early AMD, which in many people shows no symptoms or loss of vision. Your eye care professional may recommend that you get a comprehensive dilated eye exam at least once a year. The exam will help determine if your condition is advancing.

As for prevention, AMD occurs less often in people who exercise, avoid smoking, and eat nutritious foods including green leafy vegetables and fish. If you already have AMD, adopting some of these habits may help you keep your vision longer.

Intermediate and Late AMD

If you have intermediate or late AMD, you might benefit from taking supplements containing these ingredients. But first, be sure to review and compare the labels. Many supplements have different ingredients, or different doses, from those tested in the AREDS trials. Also, consult your doctor or eye care professional about which supplement, if any, is right for you. For example, if you smoke regularly, or used to, your doctor may recommend that you avoid supplements containing beta-carotene.

Even if you take a daily multivitamin, you should consider taking an AREDS supplement if you are at risk for late AMD. The formulations tested in the AREDS trials contain much higher doses of vitamins and minerals than what is found in multivitamins. Tell your doctor or eye care professional about any multivitamins you are taking when you are discussing possible AREDS formulations.

Finally, remember that the AREDS formulation is not a cure. It does not help people with early AMD, and will not restore vision already lost from AMD. But it may delay the onset of late AMD. It also may help slow vision loss in people who already have late AMD.

Advanced Neovascular AMD

Neovascular AMD typically results in severe vision loss. However, eye care professionals can try different therapies to stop further vision loss. You should remember that the therapies described below are not a cure. The condition may progress even with treatment.

Coping with AMD

AMD and vision loss can profoundly affect your life. This is especially true if you lose your vision rapidly.

In addition to getting medical treatment for AMD, there are things you can do to cope:

  This information is not a tool for self-diagnosis or a substitute for professional care.