A cataract is a cloudy or opaque area in the lens of the eye. Cataracts usually develop as a person gets older and may run in families. Other environmental factors such as smoking or exposure to toxic substances can also accelerate the development of a cataract. Cataracts can cause visual problems such as difficulty seeing at night, seeing halos around lights, and sensitivity to glare.
Reviewed By: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.