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Because as many as 75% of older adults have significant visual or auditory dysfunction not reported to their physicians, adequate screening for these problems is important. These disorders may limit functional activity and lead to social isolation and depression. Correction of remediable conditions may improve ability to perform daily activities. The key clinical points include:
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The prevalence of vision problems increases with age and many of the common causes are treatable disorders.
There are multiple rehabilitation strategies to maximize the functional independence of an individual with low vision.
The prevalence of hearing impairment increases progressively with age and some types of hearing loss can be corrected.
The combination of vision and hearing impairment may predispose to falls and the development of functional dependence.
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PHYSIOLOGICAL AND FUNCTIONAL CHANGES
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The visual system undergoes many changes with age (Table 13-1). Decreases in visual acuity in old age may be caused by morphological changes in the choroid, pigment epithelium, and retina, or by decreased function of the rods, cones, and other neural elements. Older patients frequently have difficulties turning their eyes upward or sustaining convergence. Intraocular pressure slowly increases with age.
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The refractive error may become either more hyperopic (where vision is better for distant objects than for near objects) or more myopic (where it is difficult to see objects that are far away). In younger persons, hyperopia may be overcome by the accommodative power of the ciliary muscle on the young lens. However, with age, this latent hyperopia becomes manifest because of loss of accommodative reserve.
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Other older patients may show an increase in myopia with age, caused by changes within the lens. The crystalline lens increases in size with age as old lens fibers accumulate in the lens nucleus. The nucleus becomes more compact and harder (nuclear sclerosis), increasing the refractive power of the lens and worsening the myopia.
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Another definitive refractive change of aging is the development of presbyopia from nuclear sclerosis of the lens and atrophy of ...