Senile cataracts are a clouding of the lens in the eye that develops with aging. More than 70 percent of people over age 75 have some degree of lens clouding, according to Richard Lindstrom, M.D., of ImproveYourVision.com. Senile cataracts can occur in any of three areas of the lens: the nucleus, cortex or capsule. Cataracts are not painful but can obscure vision; one eye or both may have cataracts, and more than one type of senile cataract can occur in an eye.
Nuclear
Nuclear cataracts, which are the most common type of senile cataract, develop in the nucleus, or center, of the lens. Nuclear cataracts usually develop slowly, initially causing glare and halos around objects, difficulty determining dark blue from black, loss of contrast and eventually blurry vision, the Merck Manual states. Distance vision usually worsens, but near vision temporarily improves, due to changes in the lens, a phenomenon known as "second sight." Nuclear cataracts are generally age related.
Cortical
Cortical cataracts occur in the cortex, or outside of the lens, and grow inward toward the center, like spokes on a wheel. For this reason, the appearance of cortical cataracts may be described as "cortical spoking." Cortical cataracts at a very advanced stage can make the whole lens look white. Senile cortical cataracts are generally age related and may be caused by sun exposure, but they are also commonly found in diabetics.
Posterior Subcapsular
Posterior subcapsular cataracts develop in the capsule, the membrane around the lens. Subcapsular cataracts are more common in diabetics and people who have taken steroids, as well as those who have undergone surgical procedures or who have suffered eye trauma or inflammation, according to Cataract.com. Posterior subcapsular cataracts progress rapidly, cause fewer symptoms until they're mature, and are more likely to be found in younger people than are senile cortical or nuclear cataracts. These cataracts are most likely to cause difficulty with night driving due to glare, and they decrease vision most severely when the pupil constricts during reading or in bright light.
