Cataracts are areas of clouding or opacity in the lens of the eye. If they are large enough or are located strategically in the visual path, they may reduce visual acuity. Although some cataracts that form are not part of the aging process and may occur at any age, there are cataracts that come with growing old. The first of the age-related changes may begin as early as age 40. The speed with which cataracts develop and their extent remain highly variable from person to person. The development of cataracts often causes a problem with glare.