A cataract is a clouding of the lens. It may be partial or full-scale. It may be located in the center of the lens, or in marginal areas where vision is then less disturbed. As this clouding thickens, it prevents light from passing clearly through the lens. The slight or early signs do not affect vision, but they can be detected by ophthalmic examination. As the clouding increases, the vision decreases and it cannot be corrected with glasses.
A cataract usually affects both eyes, but the vision loss may not develop equally. The exact cause of cataracts is unknown, but many factors have been identified that may promote the formation.
The most common ones are:
- High UV radiation exposure from the sun
- Eye inflammation
- Penetrating injuries
- Cataracts in conjunction with taking prescription drugs such as chemotherapy