Eye is a complex organ. There are various parts in the eye that contributes to the formation of clear and sharp image. Lens is one of the part of the eye that is transparent and allows light rays to go into the eye. There light rays are focussed on the sensitive layers of the retina and carried to brain for the clear image to be perceived.
A cataract is opacity of crystalline lens part of eye. Cataract can cause visual disturbances in vision like decreased vision, glare at night, haloes, decreased brightness . Due to visual disturbances there may be difficulty in driving, climbing stairs that may lead more falls and accidents. Various types of cataracts include:
- A subcapsular cataract occurs at the back of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.
- A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging.
- A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
Cataract is age related changes in the lens of eye leading to opacity. Besides advancing age, cataract risk factors include:
- Ultraviolet radiation
- Prolonged use of corticosteroid medications
- Statin medicines used to reduce cholesterol
- Previous eye injury or inflammation
- Previous eye surgery
- Hormone replacement therapy
- Significant alcohol consumption
- High myopia
- Family history
One theory of cataract formation is that many cataracts are caused by oxidative changes in the human lens.