A cataract is a clouding or opaque area over the lens of the eye – an area that is normally transparent. This clouding is caused when some of the protein that makes up the lens begins to clump together.
In its early stages, the cloudiness may affect only a small part of the lens. However, the cataract may grow larger over time and affect more of the lens. As less light reaches the retina, your vision may become dull and blurry. Cataracts generally do not cause surface irritation or pain. Cataracts cannot spread from one eye to another, but many people develop cataracts in both eyes.
According to the National Eye Institute, part of the National Institutes of Health (NIH), there are several different types of cataracts. These include:
Age-related cataracts: The majority of cataracts are age-related. Typically, age-related cataracts are nuclear, meaning that they develop in the center of the lens and can induce myopia (nearsightedness) – a temporary improvement in reading vision that is sometimes referred to as "second sight." Unfortunately, "second sight" disappears as the cataract grows.
Congenital cataracts: Even though most cataracts are the result of aging, in rare instances they can be present at birth (congenital).
Secondary cataracts: Secondary cataracts develop primarily as a result of another disease occurrence in the body (for instance, diabetes). Secondary cataract development also has been linked to steroid use. Secondary cataracts also can develop years after cataract surgery and often are called after-cataracts.
Traumatic cataracts: Eye(s) that have sustained an injury may develop a traumatic cataract either immediately following the incident, or several years later.
Cataracts may be inevitable, but there are things you can do to make sure you don’t get them before your time. To prevent early cataracts:
- Wear sunglasses with proper UV protection.
- Stop smoking.
- Prevent eye injury by wearing protective glasses or goggles when needed.
- Talk to your doctor about your cataract risk and how you can reduce it.
Diagnosis of cataracts
The only way to know for sure if you have a cataract is to have an eye examination that includes a complete medical history as well as diagnostic procedures and tests.
- Visual acuity test – The common eye chart test, which measures vision ability at various distances
- Pupil dilation – The pupil is widened with eye drops to allow a close-up examination of the retina.
- Visual field – Measures side or peripheral vision. Lost peripheral vision may be an indication of glaucoma.
- Slit-lamp examination – A slit lamp allows your eye doctor to see the structures at the front of your eye under magnification and detect any small abnormalities.
In its early stages, vision loss caused by a cataract may be aided with the use of different eyeglasses, a magnifying glass or stronger lighting.
Treatment for cataracts
When these measures are no longer helpful, surgery is the only effective treatment available for most people with cataracts. It is important to note that a cataract only needs to be removed when vision loss interferes with everyday activities such as driving, reading or watching television. You and your doctor can make that decision together.
Cataract surgery is highly successful, and distance vision is normally restored, although most people continue to need glasses or contact lenses to provide good vision at near or intermediate seeing distances.