Information on Eye Diseases & Disorders


Understanding the Eye

National Eye Institute (NEI), of the US National Institutes of Health (NIH), conducts and supports research. The NEI provides information on eye diseases and disorders and vision eye care. Topics are extensive and include information on:

Diabetic Retinopathy

What is diabetic eye disease?


Diabetic eye disease refers to a group of eye problems that people with diabetes may face as a complication of diabetes. All can cause severe vision loss or even blindness.

What is diabetic retinopathy?


Diabetic retinopathy is the most common diabetic eye disease and a leading cause of blindness in American adults. It is caused by changes in the blood vessels of the retina.

In some people with diabetic retinopathy, blood vessels may swell and leak fluid. In other people, abnormal new blood vessels grow on the surface of the retina. The retina is the light-sensitive tissue at the back of the eye. A healthy retina is necessary for good vision.

If you have diabetic retinopathy, at first you may not notice changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes.


A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye.

A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting.

The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. If you think you have a cataract, see an eye doctor for an exam to find out for sure.

If you think you have a cataract, see an eye doctor for an exam to find out for sure.

Age-related macular degeneration (AMD)

This information was developed by the National Eye Institute to help patients and their families search for general information about age-related macular degeneration.

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.

What is age-related macular degeneration?


Age-related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving.

AMD affects the macula, the part of the eye that allows you to see fine detail. AMD causes no pain.

In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. AMD is a leading cause of vision loss in Americans 60 years of age and older.

AMD occurs in two forms: wet and dry.

Where is the macula?


The macula is located in the center of the retina, the light-sensitive tissue at the back of the eye. The retina instantly converts light, or an image, into electrical impulses. The retina then sends these impulses, or nerve signals, to the brain.


What is Glaucoma?


Glaucoma is a group of diseases that can steal sight without warning or symptoms. Over three million Americans have it. Only half know.

Glaucoma is a group of diseases of the optic nerve involving loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Raised intraocular pressure is a significant risk factor for developing glaucoma (above 22mmHg).

One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressure for years and yet never develop damage. Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.

A downloadable School Program for Grades 4-8 entitled VISION is part of a nationwide public education program designed to mark the 25th anniversary of the National Eye Institute, part of the Federal government’s National Institute of Health.

The curriculum supplements can be used by a teacher and/or a guest speaker. This could serve as an invaluable resource for your grandchildren to introduce as a worthwhile classroom activity