eye disorders
Effects of Aging on the Eyes
Introduction
In middle age, the lens of the eye becomes less flexible and less able to thicken and thus less able to focus on nearby objects, a condition called Causes . Reading glasses or bifocal lenses can help compensate for this problem. For more information on the effects of age on the eye, see In old age, changes to the eye may include the following: Yellowing or browning of the lens caused by many years of exposure to ultraviolet light, wind, and dust Thinning of the conjunctiva A bluish hue caused by increased transparency of the sclera The number of mucous cells in the conjunctiva may decrease with age. Tear production may also decrease with age, so that fewer tears are available to keep the surface of the eye moist. Both of these changes explain why older people are more likely to have Keratoconjunctivitis Sicca . However, even though the eyes tend to be dry normally, tearing can be significant when the eyes are irritated, such as when an onion is cut or an object contacts the eye. Arcus senilis (a deposit of calcium and cholesterol salts) appears as a gray-white ring at the edge of the cornea. It is common among people older than 60. Arcus senilis does not affect vision. Some diseases of the retina are more likely to occur in old age, including Age-Related Macular Degeneration (AMD or ARMD) , The muscles that squeeze the eyelids shut decrease in strength with age. This decrease in strength, combined with gravity and age-related looseness of the eyelids, sometimes causes the lower eyelid to turn outward from the eyeball. This condition is called Entropion and Ectropion . Sometimes, because of age-related looseness affecting a different part of the eyelid, the lower eyelid turns inward, causing the eyelashes to rub against the eyeball. This condition is called In some older people, the fat around the orbit shrinks, causing the eyeball to sink backward into the orbit. This condition is called enophthalmos. Because of lax tissues in the eyelids, the orbital fat can also bulge forward into the eyelids, making them appear constantly puffy. The muscles that work to regulate the size of the pupils weaken with age. The pupils become smaller, react more sluggishly to light, and dilate more slowly in the dark. Therefore, people older than 60 may find that objects appear dimmer, that they are dazzled initially when going outdoors (or when facing oncoming cars during night driving), and that they have difficulty going from a brightly lit environment to a darker one. These changes may be particularly bothersome when combined with the effects of a cataract. Other changes in eye function also occur as people age. The sharpness of vision (acuity) is reduced despite use of the best glasses, especially in people who have a , 