Vision

There is a general decline in visual acuity with age, and nearly all individuals older than 55 years of age require vision correction for reading or distance. The decline oc­curs as a result of a smaller pupil diameter, loss of refrac­tive power of the lens, and an increase in the scattering of light. The most common visual problem among older adults is presbyopia, or difficulty focusing on near objects. It is caused mainly by decreased elasticity of the lens and atrophy of the ciliary muscle (see Chapter 54).

Glare and abrupt changes in light pose particular problems for older adults. Both are reasons that the elderly frequently give up night driving; they also increase their risk for falls and injury. Color discrimination changes also take place with aging. In particular, older adults have more difficulty identifying blues and greens. This is thought to be related to problems associated with filtering short wave­lengths of light (i.e., violet, blue, green) through a yellowed, opaque lens. Corneal sensitivity also may diminish with age, so that older adults may be less aware of injury or infection.^25,26

Ophthalmologic diseases and disorders are common in the elderly. Cataracts, glaucoma, and macular degener­ation are seen frequently and can greatly impair vision and function. Low-vision aids, such as special magnifiers and high-intensity lighting that mimics sunlight, can assist in optimizing vision in otherwise uncorrectable ophthalmo­logic problems.