Overview

Cataracts are currently the leading cause of blindness worldwide. Of the 28 million (visual acuity less than 20/400), an estimated 17 million cases are due to age-related cataracts. Moreover, the World Health Organization found that in Nepal nearly 70% of the blindness comes from cataracts. In Tibet, the problem is even worse. The 1987 Tibet Eye Study revealed that blinding cataracts are present in 18% of persons between the ages of 40 and 49 and more than 50% of those over age 70. Whether the cataracts are due to a genetic predilection, the high altitude sunlight, or dietary and other factors, is not clear. What is clear is that is is terrible to blind in the Third World in general, and nowhere is it more devastating than in the mountainous terrain of the Himalayan regions. A blind person, without family support, has an incredibly short life expectancy of about three years.

What Is a Cataract?

A cataract is a cloudy or opaque area in the normally transparent lens of the eye. As the opacity thickens, it prevents light rays from passing through the lens and focusing on the retina, the light sensitive tissue lining the back of the eye. Early lens changes or opacities may not disturb vision. But as the lens continues to change, several specific symptoms including blurred vision; sensitivity to light and glare; increased nearsightedness; or distorted images in either eye, may develop.

The lens is located behind the iris, the colored portion of the eye, and the pupil, the dark center of the eye. Tiny ligaments, called zonules, support the lens capsule within the eye.

The lens has three parts, the capsule, the nucleus, and the cortex. The outer membrane, or capsule, surrounds the cortex which in turn surrounds the center or nucleus of the lens. If you imagine the lens as a piece of fruit, the capsule is the skin, the cortex is the fleshy fruit, and the nucleus is the pit.