A cataract occurs when the lens of the eye becomes cloudy and obscures vision. There are several types of cataracts such as cortical, which occur in the cortex of the lens; nuclear, which occur in the nucleus of the lens; or subcapsular, which occurs just under the capsule. Subcapsular cataracts tend to occur in younger people and the curative treatment is surgical removal. People at risk for these types of lesions should be followed by an eye doctor.
There are two main types of subcapsular cataracts: anterior and posterior. Anterior subcapsular cataracts are much less common than posterior subcapsular cataracts (PSC). PSC usually present as a small white opacity just under the back capsule of the lens and right in the path of light traveling to the retina. This type of cataract also can develop faster than other types of cataracts.
Subcapsular cataracts tend to occur in younger patients and in patients with certain diseases or who take certain medications. People with PSC have difficulty with glare (problems seeing in a bright light) and more difficulty with near vision than with distance vision. Even when the cataract is small in size, it can still create a significant amount of interference with the activities of daily living.
People with diabetes mellitus are at risk for multiple eye conditions; according to the American Diabetes Association, people with diabetes are 60 percent more likely to develop all types of cataracts compared with other people. Cataracts in diabetic patients also can develop quickly and happen at a younger age. High blood sugar levels are thought to cause these cataracts and tight blood sugar control may slow down or halt their development. Diabetics are at high risk of developing subcapsular cataracts.
Steroid medications can be used with a physician's guidance to treat patients with a variety of conditions such as people with asthma or allergies or those undergoing organ transplants. Several forms of steroids--oral, inhaled or eye drops--have been linked to higher risk of development of subcapsular cataracts. Researchers are not completely sure of the mechanism for the development of cataracts in people using steroid medications but patients using these medications need to be evaluated by an eye doctor regularly to make sure that cataracts are not forming.
Patients with specific genetic diseases like retinitis pigmentosa may be at higher risk for developing a subcapsular cataract. In these patients, the posterior subcapsular cataract develops early but does not interfere with vision until later in the disease course when the patient's visual field becomes very small. There are other genetic conditions that may increase the risk as well. If other members of a family developed this type of cataract, a person may be at higher risk for developing them.
People who are very near-sighted (myopia) or very far-sighted (hyperopia) may be at higher risk of developing posterior subcapsular cataracts as well as those who have a chronic inflammatory eye disease such as retinitis. People who suffer trauma to the eye may also develop a posterior subcapsular cataract at a later date. Radiation to the eye may also cause this type of cataract. Frequent monitoring by an eye doctor and diligence on the part of the patient to report any visual changes is very important for these people.