cataract 

A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing facesIn cataract surgery, the natural lens of the patient's eye, which is cloudy, is replaced with a transparent artificial lens.