Cataract

A cataract is the clouding of the eye’s natural lens. In their early stages, cataracts cause hazy, blurred vision. As a cataract progresses, it can lead to low vision and ultimately to complete blindness in the affected eye.

Cataracts are the world’s leading cause of blindness: Epidemiologic models estimate that approximately 15 million people globally are blind due to untreated cataracts, with an additional 85 million suffering from low vision. Cataracts are especially common in the elderly, with approximately 50 percent of people over age 70 afflicted by cataracts in one or both eyes. The conventional treatment for cataracts is surgery to replace the clouded natural lens with an artificial one made of clear plastic. In regions of the world where access to cataract surgery and follow-up medical care is limited, untreated cataracts are the most common cause of blindness.

Cataracts commonly form when crystallin proteins become misshapen, and their refractive properties change. Furthermore, misshapen crystallin proteins aggregate into amyloid tangles, causing the lens becomes increasingly opaque.

Electron micrograph (at larger scale) of aggregated alpha-crystallin protein, which contributes to opacity of the lens in cataracts

Electron micrograph (at larger scale) of aggregated alpha-crystallin protein, which contributes to opacity of the lens in cataracts

Electron micrograph of alpha crystallin protein in its normal conformation, as it exists in healthy, transparent lenses

Electron micrograph of alpha crystallin protein in its normal conformation, as it exists in healthy, transparent lenses