Cataract

Clouding of the lens, the leading cause of blindness worldwide

Overview

A cataract is a clouding of the normally clear crystalline lens of the eye. Most cataracts are age related, but other risk factors include ultraviolet exposure, smoking, diabetes, long term corticosteroid use, eye trauma, and inflammation, and some are present from birth. Symptoms develop gradually and include dim or blurred vision, glare and halos around lights at night, faded or yellowed colors, and frequent changes in spectacle prescription. According to the World Health Organization, cataract is the leading cause of blindness worldwide, a burden concentrated in low and middle income countries where access to surgery is limited. Treatment is surgical: the cloudy lens is removed, usually by phacoemulsification, and replaced with an artificial intraocular lens. Cataract surgery is among the most frequently performed surgical procedures in the world and has a high success rate, and the choice of implant can also correct preexisting refractive errors such as astigmatism.