Cataracts are cloudy areas that form in the lens of the eye and result in a gradual painless reduction in sight. Poor vision results because the cloudiness interferes with light entering the eye, with the opacities in the lens scattering the light, in the same way that a dirty window scatters light. The time taken for this to happen varies from a few months to many years.
Most cataracts are a result of ageing and long-term exposure to ultraviolet light. Some are caused by injury, certain diseases and in rare cases by exposure to toxic materials and radiation. Other symptoms include blurred or hazy vision, spots before the eyes, double vision and a marked increase in sensitivity to glare, particularly for night driving.
There is no proven method of preventing cataracts. Long-term exposure to ultraviolet light is thought to induce cataracts, so a brimmed hat and approved sunglasses should be worn in sunlight.
Cataract surgery is now a relatively minor procedure. Often it is performed under a local anaesthetic, generally in a day surgery facility. The surgery is performed by an ophthalmologist, a medical doctor who specialises in eye surgery.