Points to Remember

1. Diabetic eye disease comprises a group of eye conditions that affect people with diabetes. These conditions include diabetic retinopathy, diabetic macular edema (DME), cataract, and glaucoma.
2. All forms of diabetic eye disease have the potential to cause severe vision loss and blindness.
3. Diabetic retinopathy involves changes to retinal blood vessels that can cause them to bleed or leak fluid, distorting vision.
4. Diabetic retinopathy is the most common cause of vision loss among people with diabetes and a leading cause of blindness among working-age adults.
5. DME is a consequence of diabetic retinopathy that causes swelling in the area of the retina called the macula.
6. Controlling diabetes—by taking medications as prescribed, staying physically active, and maintaining a healthy diet—can prevent or delay vision loss.
7. Because diabetic retinopathy often goes unnoticed until vision loss occurs, people with diabetes should get a comprehensive dilated eye exam at least once a year.
8. Early detection, timely treatment, and appropriate follow-up care of diabetic eye disease can protect against vision loss.
9. Diabetic retinopathy can be treated with several therapies, used alone or in combination.
10. NEI supports research to develop new therapies for diabetic retinopathy, and to compare the effectiveness of existing therapies for different patient groups.

What is diabetic eye disease?

Diabetic eye disease is a group of eye conditions that can affect people with diabetes.

• Diabetic retinopathy affects blood vessels in the light-sensitive tissue called the retina that lines the back of the eye. It is the most common cause of vision loss among people with diabetes and the leading cause of vision impairment and blindness among working-age adults.
• Diabetic macular edema (DME). A consequence of diabetic retinopathy, DME is swelling in an area of the retina called the macula.

Diabetic eye disease also includes cataract and glaucoma:

• Cataract is a clouding of the eye’s lens. Adults with diabetes are 2-5 times more likely than those without diabetes to develop cataract. Cataract also tends to develop at an earlier age in people with diabetes.
• Glaucoma is a group of diseases that damage the eye’s optic nerve—the bundle of nerve fibers that connects the eye to the brain. Some types of glaucoma are associated with elevated pressure inside the eye. In adults, diabetes nearly doubles the risk of glaucoma.

All forms of diabetic eye disease have the potential to cause severe vision loss and blindness.

Diabetic Retinopathy

What causes diabetic retinopathy?

Chronically high blood sugar from diabetes is associated with damage to the tiny blood vessels in the retina, leading to diabetic retinopathy. The retina detects light and converts it to signals sent through the optic nerve to the brain. Diabetic retinopathy can cause blood vessels in the retina to leak fluid or hemorrhage (bleed), distorting vision. In its most advanced stage, new abnormal blood vessels proliferate (increase in number) on the surface of the retina, which can lead to scarring and cell loss in the retina.

Diabetic retinopathy may progress through four stages:

1. Mild nonproliferative retinopathy. Small areas of balloon-like swelling in the retina’s tiny blood vessels, called microaneurysms, occur at this earliest stage of the disease. These microaneurysms may leak fluid into the retina.
2. Moderate nonproliferative retinopathy. As the disease progresses, blood vessels that nourish the retina may swell and distort. They may also lose their ability to transport blood. Both conditions cause characteristic changes to the appearance of the retina and may contribute to DME.
3. Severe nonproliferative retinopathy. Many more blood vessels are blocked, depriving blood supply to areas of the retina. These areas secrete growth factors that signal the retina to grow new blood vessels.
4. Proliferative diabetic retinopathy (PDR). At this advanced stage, growth factors secreted by the retina trigger the proliferation of new blood vessels, which grow along the inside surface of the retina and into the vitreous gel, the fluid that fills the eye. The new blood vessels are fragile, which makes them more likely to leak and bleed. Accompanying scar tissue can contract and cause retinal detachment—the pulling away of the retina from underlying tissue, like wallpaper peeling away from a wall. Retinal detachment can lead to permanent vision loss.

What is diabetic macular edema (DME)?

DME is the build-up of fluid (edema) in a region of the retina called the macula. The macula is important for the sharp, straight-ahead vision that is used for reading, recognizing faces, and driving. DME is the most common cause of vision loss among people with diabetic retinopathy. About half of all people with diabetic retinopathy will develop DME. Although it is more likely to occur as diabetic retinopathy worsens, DME can happen at any stage of the disease.

Who is at risk for diabetic retinopathy?

People with all types of diabetes (type 1, type 2, and gestational) are at risk for diabetic retinopathy. Risk increases the longer a person has diabetes. Between 40 and 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy, although only about half are aware of it. Women who develop or have diabetes during pregnancy may have rapid onset or worsening of diabetic retinopathy.

Symptoms and Detection

What are the symptoms of diabetic retinopathy and DME?

The early stages of diabetic retinopathy usually have no symptoms. The disease often progresses unnoticed until it affects vision. Bleeding from abnormal retinal blood vessels can cause the appearance of “floating” spots. These spots sometimes clear on their own. But without prompt treatment, bleeding often recurs, increasing the risk of permanent vision loss. If DME occurs, it can cause blurred vision.

How are diabetic retinopathy and DME detected?

Diabetic retinopathy and DME are detected during a comprehensive dilated eye exam that includes:

1. Visual acuity testing. This eye chart test measures a person’s ability to see at various distances.
2. Tonometry. This test measures pressure inside the eye.
3. Pupil dilation. Drops placed on the eye’s surface dilate (widen) the pupil, allowing a physician to examine the retina and optic nerve.
4. Optical coherence tomography (OCT). This technique is similar to ultrasound but uses light waves instead of sound waves to capture images of tissues inside the body. OCT provides detailed images of tissues that can be penetrated by light, such as the eye.

A comprehensive dilated eye exam allows the doctor to check the retina for:

1. Changes to blood vessels
2. Leaking blood vessels or warning signs of leaky blood vessels, such as fatty deposits
3. Swelling of the macula (DME)
4. Changes in the lens
5. Damage to nerve tissue

If DME or severe diabetic retinopathy is suspected, a fluorescein angiogram may be used to look for damaged or leaky blood vessels. In this test, a fluorescent dye is injected into the bloodstream, often into an arm vein. Pictures of the retinal blood vessels are taken as the dye reaches the eye.

Prevention and Treatment

How can people with diabetes protect their vision?

Vision lost to diabetic retinopathy is sometimes irreversible. However, early detection and treatment can reduce the risk of blindness by 95 percent. Because diabetic retinopathy often lacks early symptoms, people with diabetes should get a comprehensive dilated eye exam at least once a year. People with diabetic retinopathy may need eye exams more frequently. Women with diabetes who become pregnant should have a comprehensive dilated eye exam as soon as possible. Additional exams during pregnancy may be needed.

Studies such as the Diabetes Control and Complications Trial (DCCT) have shown that controlling diabetes slows the onset and worsening of diabetic retinopathy. DCCT study participants who kept their blood glucose level as close to normal as possible were significantly less likely than those without optimal glucose control to develop diabetic retinopathy, as well as kidney and nerve diseases. Other trials have shown that controlling elevated blood pressure and cholesterol can reduce the risk of vision loss among people with diabetes.

Treatment for diabetic retinopathy is often delayed until it starts to progress to PDR, or when DME occurs. Comprehensive dilated eye exams are needed more frequently as diabetic retinopathy becomes more severe. People with severe nonproliferative diabetic retinopathy have a high risk of developing PDR and may need a comprehensive dilated eye exam as often as every 2 to 4 months.

How is DME treated?

DME can be treated with several therapies that may be used alone or in combination.

Anti-VEGF Injection Therapy. Anti-VEGF drugs are injected into the vitreous gel to block a protein called vascular endothelial growth factor (VEGF), which can stimulate abnormal blood vessels to grow and leak fluid. Blocking VEGF can reverse abnormal blood vessel growth and decrease fluid in the retina. Available anti-VEGF drugs include Avastin (bevacizumab), Lucentis (ranibizumab), and Eylea (aflibercept). Lucentis and Eylea are approved by the U.S. Food and Drug Administration (FDA) for treating DME. Avastin was approved by the FDA to treat cancer, but is commonly used to treat eye conditions, including DME.

The NEI-sponsored Diabetic Retinopathy Clinical Research Network compared Avastin, Lucentis, and Eylea in a clinical trial. The study found all three drugs to be safe and effective for treating most people with DME. Patients who started the trial with 20/40 or better vision experienced similar improvements in vision no matter which of the three drugs they were given. However, patients who started the trial with 20/50 or worse vision had greater improvements in vision with Eylea.

Most people require monthly anti-VEGF injections for the first six months of treatment. Thereafter, injections are needed less often: typically three to four during the second six months of treatment, about four during the second year of treatment, two in the third year, one in the fourth year, and none in the fifth year. Dilated eye exams may be needed less often as the disease stabilizes.

Avastin, Lucentis, and Eylea vary in cost and in how often they need to be injected, so patients may wish to discuss these issues with an eye care professional.

Focal/grid macular laser surgery. In focal/grid macular laser surgery, a few to hundreds of small laser burns are made to leaking blood vessels in areas of edema near the center of the macula. Laser burns for DME slow the leakage of fluid, reducing swelling in the retina. The procedure is usually completed in one session, but some people may need more than one treatment. Focal/grid laser is sometimes applied before anti-VEGF injections, sometimes on the same day or a few days after an anti-VEGF injection, and sometimes only when DME fails to improve adequately after six months of anti-VEGF therapy.

Corticosteroids. Corticosteroids, either injected or implanted into the eye, may be used alone or in combination with other drugs or laser surgery to treat DME. The Ozurdex (dexamethasone) implant is for short-term use, while the Iluvien (fluocinolone acetonide) implant is longer lasting. Both are biodegradable and release a sustained dose of corticosteroids to suppress DME. Corticosteroid use in the eye increases the risk of cataract and glaucoma. DME patients who use corticosteroids should be monitored for increased pressure in the eye and glaucoma.

How is proliferative diabetic retinopathy (PDR) treated?

For decades, PDR has been treated with scatter laser surgery, sometimes called panretinal laser surgery or panretinal photocoagulation. Treatment involves making 1,000 to 2,000 tiny laser burns in areas of the retina away from the macula. These laser burns are intended to cause abnormal blood vessels to shrink. Although treatment can be completed in one session, two or more sessions are sometimes required. While it can preserve central vision, scatter laser surgery may cause some loss of side (peripheral), color, and night vision. Scatter laser surgery works best before new, fragile blood vessels have started to bleed. Recent studies have shown that anti-VEGF treatment not only is effective for treating DME, but is also effective for slowing progression of diabetic retinopathy, including PDR, so anti-VEGF is increasingly used as a first-line treatment for PDR.

What is a vitrectomy?

A vitrectomy is the surgical removal of the vitreous gel in the center of the eye. The procedure is used to treat severe bleeding into the vitreous, and is performed under local or general anesthesia. Ports (temporary water-tight openings) are placed in the eye to allow the surgeon to insert and remove instruments, such as a tiny light or a small vacuum called a vitrector. A clear salt solution is gently pumped into the eye through one of the ports to maintain eye pressure during surgery and to replace the removed vitreous. The same instruments used during vitrectomy also may be used to remove scar tissue or to repair a detached retina.

Vitrectomy may be performed as an outpatient procedure or as an inpatient procedure, usually requiring a single overnight stay in the hospital. After treatment, the eye may be covered with a patch for days to weeks and may be red and sore. Drops may be applied to the eye to reduce inflammation and the risk of infection. If both eyes require vitrectomy, the second eye usually will be treated after the first eye has recovered.

What if treatment doesn’t improve vision?

An eye care professional can help locate and make referrals to low vision and rehabilitation services and suggest devices that may help make the most of remaining vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairment. A nearby school of medicine or optometry also may provide low vision and rehabilitation services.

This information was developed by the National Eye Institute to help patients and their families search for general information about glaucoma. An eye care professional who has examined the patient’s eyes and is familiar with his or her medical history is the best person to answer specific questions.

Glaucoma Defined

What is Glaucoma?

Glaucoma is a group of diseases that damage the eye’s optic nerve and can result in vision loss and blindness. However, with early detection and treatment, you can often protect your eyes against serious vision loss.

The optic nerve

The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. (See diagram above.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.

How does the optic nerve get damaged by open-angle glaucoma?

Several large studies have shown that eye pressure is a major risk factor for optic nerve damage. In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of the chamber and nourishes nearby tissues. The fluid leaves the chamber at the open angle where the cornea and iris meet. (See diagram below.) When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

In open-angle glaucoma, even though the drainage angle is “open”, the fluid passes too slowly through the meshwork drain. Since the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma-and vision loss—may result. That’s why controlling pressure inside the eye is important.

Another risk factor for optic nerve damage relates to blood pressure. Thus, it is important to also make sure that your blood pressure is at a proper level for your body by working with your medical doctor.

Fluid pathway is shown in teal.

Can I develop glaucoma if I have increased eye pressure?

Not necessarily. Not every person with increased eye pressure will develop glaucoma. Some people can tolerate higher levels of eye pressure better than others. Also, a certain level of eye pressure may be high for one person but normal for another.

Whether you develop glaucoma depends on the level of pressure your optic nerve can tolerate without being damaged. This level is different for each person. That’s why a comprehensive dilated eye exam is very important. It can help your eye care professional determine what level of eye pressure is normal for you.

Can I develop glaucoma without an increase in my eye pressure?

Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is called low-tension or normal-tension glaucoma. It is a type of open-angle glaucoma.

Who is at risk for open-angle glaucoma?

Anyone can develop glaucoma. Some people, listed below, are at higher risk than others:

• African Americans over age 40
• Everyone over age 60, especially Mexican Americans
• People with a family history of glaucoma

A comprehensive dilated eye exam can reveal more risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy. In some people with certain combinations of these high-risk factors, medicines in the form of eyedrops reduce the risk of developing glaucoma by about half.

Glaucoma Symptoms

At first, open-angle glaucoma has no symptoms. It causes no pain. Vision stays normal. Glaucoma can develop in one or both eyes.

Without treatment, people with glaucoma will slowly lose their peripheral (side) vision. As glaucoma remains untreated, people may miss objects to the side and out of the corner of their eye. They seem to be looking through a tunnel. Over time, straight-ahead (central) vision may decrease until no vision remains.

How is glaucoma detected?

Glaucoma is detected through a comprehensive dilated eye exam that includes the following:

Visual acuity test. This eye chart test measures how well you see at various distances.

Visual field test. This test measures your peripheral (side vision). It helps your eye care professional tell if you have lost peripheral vision, a sign of glaucoma.

Dilated eye exam. In this exam, drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.

Tonometry is the measurement of pressure inside the eye by using an instrument called a tonometer. Numbing drops may be applied to your eye for this test. A tonometer measures pressure inside the eye to detect glaucoma.

Pachymetry is the measurement of the thickness of your cornea. Your eye care professional applies a numbing drop to your eye and uses an ultrasonic wave instrument to measure the thickness of your cornea.

Can glaucoma be cured?

No. There is no cure for glaucoma. Vision lost from the disease cannot be restored.

Glaucoma Treatments

Immediate treatment for early-stage, open-angle glaucoma can delay progression of the disease. That’s why early diagnosis is very important.

Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.

Medicines. Medicines, in the form of eyedrops or pills, are the most common early treatment for glaucoma. Taken regularly, these eyedrops lower eye pressure. Some medicines cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye.

Before you begin glaucoma treatment, tell your eye care professional about other medicines and supplements that you are taking. Sometimes the drops can interfere with the way other medicines work.

Glaucoma medicines need to be taken regularly as directed by your eye care professional. Most people have no problems. However, some medicines can cause headaches or other side effects. For example, drops may cause stinging, burning, and redness in the eyes.

Many medicines are available to treat glaucoma. If you have problems with one medicine, tell your eye care professional. Treatment with a different dose or a new medicine may be possible.

Because glaucoma often has no symptoms, people may be tempted to stop taking, or may forget to take, their medicine. You need to use the drops or pills as long as they help control your eye pressure. Regular use is very important.

A tonometer measures pressure inside the eye to detect glaucoma.

Make sure your eye care professional shows you how to put the drops into your eye. For tips on using your glaucoma eyedrops, see the inside back cover of this booklet.

Laser trabeculoplasty. Laser trabeculoplasty helps fluid drain out of the eye. Your doctor may suggest this step at any time. In many cases, you will need to keep taking glaucoma medicines after this procedure.

Laser trabeculoplasty is performed in your doctor’s office or eye clinic. Before the surgery, numbing drops are applied to your eye. As you sit facing the laser machine, your doctor holds a special lens to your eye. A high-intensity beam of light is aimed through the lens and reflected onto the meshwork inside your eye. You may see flashes of bright green or red light. The laser makes several evenly spaced burns that stretch the drainage holes in the meshwork. This allows the fluid to drain better.

Like any surgery, laser surgery can cause side effects, such as inflammation. Your doctor may give you some drops to take home for any soreness or inflammation inside the eye. You will need to make several follow-up visits to have your eye pressure and eye monitored.

If you have glaucoma in both eyes, usually only one eye will be treated at a time. Laser treatments for each eye will be scheduled several days to several weeks apart.

Studies show that laser surgery can be very good at reducing the pressure in some patients. However, its effects can wear off over time. Your doctor may suggest further treatment.

Conventional surgery. Conventional surgery makes a new opening for the fluid to leave the eye. (See diagram on the next page.) Your doctor may suggest this treatment at any time. Conventional surgery often is done after medicines and laser surgery have failed to control pressure.

Conventional surgery, called trabeculectomy, is performed in an operating room. Before the surgery, you are given medicine to help you relax. Your doctor makes small injections around the eye to numb it. A small piece of tissue is removed to create a new channel for the fluid to drain from the eye. This fluid will drain between the eye tissue layers and create a blister-like “filtration bleb.”

For several weeks after the surgery, you must put drops in the eye to fight infection and inflammation. These drops will be different from those you may have been using before surgery.

Conventional surgery is performed on one eye at a time. Usually the operations are four to six weeks apart.

Conventional surgery is about 60 to 80 percent effective at lowering eye pressure. If the new drainage opening narrows, a second operation may be needed. Conventional surgery works best if you have not had previous eye surgery, such as a cataract operation.

Sometimes after conventional surgery, your vision may not be as good as it was before conventional surgery. Conventional surgery can cause side effects, including cataract, problems with the cornea, inflammation, infection inside the eye, or low eye pressure problems. If you have any of these problems, tell your doctor so a treatment plan can be developed.

What are some other forms of glaucoma and how are they treated?

Open-angle glaucoma is the most common form. Some people have other types of the disease.

In low-tension or normal-tension glaucoma, optic nerve damage and narrowed side vision occur in people with normal eye pressure. Lowering eye pressure at least 30 percent through medicines slows the disease in some people. Glaucoma may worsen in others despite low pressures.

A comprehensive medical history is important to identify other potential risk factors, such as low blood pressure, that contribute to low-tension glaucoma. If no risk factors are identified, the treatment options for low-tension glaucoma are the same as for open-angle glaucoma.

In angle-closure glaucoma, the fluid at the front of the eye cannot drain through the angle and leave the eye. The angle gets blocked by part of the iris. People with this type of glaucoma may have a sudden increase in eye pressure. Symptoms include severe pain and nausea, as well as redness of the eye and blurred vision. If you have these symptoms, you need to seek treatment immediately. This is a medical emergency. If your doctor is unavailable, go to the nearest hospital or clinic. Without treatment to restore the flow of fluid, the eye can become blind. Usually, prompt laser surgery and medicines can clear the blockage, lower eye pressure, and protect vision.

In congenital glaucoma, children are born with a defect in the angle of the eye that slows the normal drainage of fluid. These children usually have obvious symptoms, such as cloudy eyes, sensitivity to light, and excessive tearing. Conventional surgery typically is the suggested treatment, because medicines are not effective and can cause more serious side effects in infants and be difficult to administer. Surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.

Conventional surgery makes a new opening for the fluid to leave the eye.

Secondary glaucomas can develop as complications of other medical conditions. For example, a severe form of glaucoma is called neovascular glaucoma, and can be a result from poorly controlled diabetes or high blood pressure. Other types of glaucoma sometimes occur with cataract, certain eye tumors, or when the eye is inflamed or irritated by a condition called uveitis. Sometimes glaucoma develops after other eye surgeries or serious eye injuries. Steroid drugs used to treat eye inflammations and other diseases can trigger glaucoma in some people. There are two eye conditions known to cause secondary forms of glaucoma.

Pigmentary glaucoma occurs when pigment from the iris sheds off and blocks the meshwork, slowing fluid drainage.

Pseudoexfoliation glaucoma occurs when extra material is produced and shed off internal eye structures and blocks the meshwork, again slowing fluid drainage.

Depending on the cause of these secondary glaucomas, treatment includes medicines, laser surgery, or conventional or other glaucoma surgery.

What research is being done?

Through studies in the laboratory and with patients, NEI is seeking better ways to detect, treat, and prevent vision loss in people with glaucoma. For example, researchers have discovered genes that could help explain how glaucoma damages the eye.

NEI also is supporting studies to learn more about who is likely to get glaucoma, when to treat people who have increased eye pressure, and which treatment to use first.

What You Can Do

If you are being treated for glaucoma, be sure to take your glaucoma medicine every day. See your eye care professional regularly.

You also can help protect the vision of family members and friends who may be at high risk for glaucoma-African Americans over age 40; everyone over age 60, especially Mexican Americans; and people with a family history of the disease. Encourage them to have a comprehensive dilated eye exam at least once every two years. Remember that lowering eye pressure in the early stages of glaucoma slows progression of the disease and helps save vision.

Medicare covers an annual comprehensive dilated eye exam for some people at high risk for glaucoma. These people include those with diabetes, those with a family history of glaucoma, and African Americans age 50 and older.

What should I ask my eye care professional?

You can protect yourself against vision loss by working in partnership with your eye care professional. Ask questions and get the information you need to take care of yourself and your family.

What are some questions to ask?

About my eye disease or disorder…

• What is my diagnosis?
• What caused my condition?
• Can my condition be treated?
• How will this condition affect my vision now and in the future?
• Should I watch for any particular symptoms and notify you if they occur?
• Should I make any lifestyle changes?

About my treatment…

• What is the treatment for my condition?
• When will the treatment start and how long will it last?
• What are the benefits of this treatment and how successful is it?
• What are the risks and side effects associated with this treatment?
• Are there foods, medicines, or activities I should avoid while I’m on this treatment?
• If my treatment includes taking medicine, what should I do if I miss a dose?
• Are other treatments available?

About my tests…

• What kinds of tests will I have?
• What can I expect to find out from these tests?
• When will I know the results?
• Do I have to do anything special to prepare for any of the tests?
• Do these tests have any side effects or risks?
• Will I need more tests later?

Other suggestions

• If you don’t understand your eye care professional’s responses, ask questions until you do understand.
• Take notes or get a friend or family member to take notes for you. Or, bring a tape recorder to help you remember the discussion.
• Ask your eye care professional to write down his or her instructions to you.
• Ask your eye care professional for printed material about your condition.
• If you still have trouble understanding your eye care professional’s answers, ask where you can go for more information.
• Other members of your healthcare team, such as nurses and pharmacists, can be good sources of information. Talk to them, too.

Today, patients take an active role in their health care. Be an active patient about your eye care.

Loss of Vision

If you have lost some sight from glaucoma, ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. Ask for a referral to a specialist in low vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments.

How should I use my glaucoma eyedrops?

If eyedrops have been prescribed for treating your glaucoma, you need to use them properly, as instructed by your eye care professional. Proper use of your glaucoma medication can improve the medicine’s effectiveness and reduce your risk of side effects.

To properly apply your eyedrops, follow these steps:

• Wash your hands.
• Hold the bottle upside down.
• Tilt your head back.
• Hold the bottle in one hand and place it as close as possible to the eye.
• With the other hand, pull down your lower eyelid. This forms a pocket.
• Place the prescribed number of drops into the lower eyelid pocket. If you are using more than one eyedrop, be sure to wait at least 5 minutes before applying the second eyedrop.
• Close your eye OR press the lower lid lightly with your finger for at least 1 minute. Either of these steps keeps the drops in the eye and helps prevent the drops from draining into the tear duct, which can increase your risk of side effects.

This information was developed by the National Eye Institute to help patients and their families search for general information about refractive errors. An eye care professional who has examined the patient’s eyes and is familiar with his or her medical history is the best person to answer specific questions.

Refractive Errors Defined

What are refractive errors?

Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens can cause refractive errors.

What is refraction?

Refraction is the bending of light as it passes through one object to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.

Frequently Asked Questions about Refractive Errors

What are the different types of refractive errors?

The most common types of refractive errors are myopia, hyperopia, presbyopia, and astigmatism.

Myopia (nearsightedness) is a condition where objects up close appear clearly, while objects far away appear blurry. With myopia, light comes to focus in front of the retina instead of on the retina.

Hyperopia (farsightedness) is a common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects at any distance, near or far.

Astigmatism is a condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out.

Presbyopia is an age-related condition in which the ability to focus up close becomes more difficult. As the eye ages, the lens can no longer change shape enough to allow the eye to focus close objects clearly.

Risk Factors

Who is at risk for refractive errors?

Presbyopia affects most adults over age 35. Other refractive errors can affect both children and adults. Individuals that have parents with certain refractive errors may be more likely to get one or more refractive errors.

Symptoms and Detection

What are the signs and symptoms of refractive errors?

Blurred vision is the most common symptom of refractive errors. Other symptoms may include:

• Double vision
• Haziness
• Glare or halos around bright lights
• Squinting
• Headaches
• Eye strain

How are refractive errors diagnosed?

An eye care professional can diagnose refractive errors during a comprehensive dilated eye examination. People with a refractive error often visit their eye care professional with complaints of visual discomfort or blurred vision. However, some people don’t know they aren’t seeing as clearly as they could.

Treatment

How are refractive errors treated?

Refractive errors can be corrected with eyeglasses, contact lenses, or surgery.

Eyeglasses are the simplest and safest way to correct refractive errors. Your eye care professional can prescribe appropriate lenses to correct your refractive error and give you optimal vision.

Contact Lenses work by becoming the first refractive surface for light rays entering the eye, causing a more precise refraction or focus. In many cases, contact lenses provide clearer vision, a wider field of vision, and greater comfort. They are a safe and effective option if fitted and used properly. It is very important to wash your hands and clean your lenses as instructed in order to reduce the risk of infection.

If you have certain eye conditions you may not be able to wear contact lenses. Discuss this with your eye care professional.

Refractive Surgery aims to change the shape of the cornea permanently. This change in eye shape restores the focusing power of the eye by allowing the light rays to focus precisely on the retina for improved vision. There are many types of refractive surgeries. Your eye care professional can help you decide if surgery is an option for you.