A cataract is a clouding of the lens of the eye.
This article focuses on cataracts in adults. For information on cataracts in children, see: Congenital cataracts
Causes, incidence, and risk factors
The lens of the eye is normally clear. It acts like the lens on a camera, focusing light as it passes to the back of the eye.
Until a person is around age 45, the shape of the lens is able to change. This allows the lens to focus on an object, whether it is close or far away.
As we age, proteins in the lens begin to break down and the lens becomes cloudy. What the eye sees may appear blurry. This condition is known as a cataract.
Factors that may speed up cataract formation are:
- Eye inflammation
- Eye injury
- Family history of cataracts
- Long-term use of corticosteroids (taken by mouth) or certain other medications
- Radiation exposure
- Smoking
- Surgery for another eye problem
- Too much exposure to ultraviolet light (sunlight)
In many cases, the cause of cataract is unknown.
Symptoms
Adult cataracts develop slowly and painlessly. Vision in the affected eye or eyes slowly gets worse.
- Mild clouding of the lens often occurs after age 60, but it may not cause any vision problems.
- By age 75, most people have cataracts that affect their vision.
Visual problems may include the following changes:
- Being sensitive to glare
- Cloudy, fuzzy, foggy, or filmy vision
- Difficulty seeing at night or in dim light
- Double vision
- Loss of color intensity
- Problems seeing shapes against a background or the difference between shades of colors
- Seeing halos around lights
Cataracts generally lead to decreased vision, even in daylight. Most people with cataracts have similar changes in both eyes, although one eye may be worse than the other. Many people with this condition have only mild vision changes.
Other symptoms may include:
- Frequent changes in eyeglass prescription
Signs and tests
A standard eye exam and slit-lamp examination are used to diagnose cataracts. Other diagnostic tests are rarely needed, except to rule out other possible causes of poor vision.
Treatment
The following may help people who have an early cataract:
- Better eyeglasses
- Better lighting
- Magnifying lenses
- Sunglasses
As vision gets worse, you may need to make changes around the home to avoid falls and injuries.
The only treatment for a cataract is surgery to remove it. Surgery is done if you cannot perform normal activities, such as driving, reading, or looking at computer or video screens, even with glasses.
If a cataract is not bothersome, surgery is usually not necessary. Cataracts usually do not harm your eye, so you can have surgery when it is convenient for you.
However, some people may have additional eye problems, such as diabetic retinopathy, that cannot be treated without first having cataract surgery.
