A cataract is a cloudy or opaque area in the normally clear lens of the eye. Depending upon its size and location, it can interfere with normal vision. It is said to be painless. Most cataracts develop in people over age 55, but they occasionally occur in infants and young children. Usually cataracts develop in both eyes, but one may be worse than the other.
The lens is located inside the eye behind the iris, the colored part of the eye. The lens focuses light on the back of the eye, the retina. The lens is made of mostly proteins and water. Clouding of the lens occurs due to changes in the proteins and lens fibers.Cataracts generally form very slowly. Signs and symptoms of a cataract may include:
- Blurred, hazy, or vision
- Reduced intensity of colors
- Increased sensitivity to glare from lights, particularly when driving at night
- Increased difficulty seeing at night
- Change in the eye's refractive error
Most cataracts are due to age-related changes in the lens. However, other factors can contribute to their development including:
- Diabetes mellitus - Persons with diabetes are at higher risk for cataracts.
- Drugs - Certain medications have been found to be associated with the development of a cataract. These include:
- Chlorpromazine and other phenothiazine related medications
- Ultraviolet Radiation - Studies have shown that there is an increased chance of cataract formation with unprotected exposure to ultraviolet (UV) radiation.
- Smoking - An association between smoking and increased nuclear opacities has been reported.
- Alcohol - Several studies have shown increased cataract formation in patients with higher alcohol consumption compared with people who have lower or no alcohol consumption.
- Nutritional Deficiency - Although the results are inconclusive, studies have suggested an association between cataract formation and low levels of antioxidants (e.g. vitamin C, vitamin E, carotenoids). Further studies may show that antioxidants have a significant effect on decreasing cataract development.