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.
Physiological and Functional Changes
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.
Table 13–1. Physiological and Functional Changes of the Eye |Favorite Table|Download (.pdf)
Table 13–1. Physiological and Functional Changes of the Eye
Morphological change in choroid, pigment epithelium, or retina
Decreased function of rods, cones, or other neural elements
Difficulty in gazing upward and maintaining convergence
Increased hyperopia and myopia
Increased lens size
Nuclear sclerosis (lens)
Ciliary muscle atrophy
Decreased lacrimal gland function
Decreased goblet cell secretion
Loss of endothelial integrity
Posterior surface pigmentation
The refractive error may become either more hyperopic or more myopic. 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.
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.
Another definitive refractive change of aging is the development of presbyopia from nuclear sclerosis of the lens and atrophy of the ciliary muscle. As a result, the closest distance at which one can see clearly slowly recedes with age. At approximately age 45, the near point of accommodation is so far that comfortable reading and near work become cumbersome and difficult. Corrective lenses are then needed to enable the patient to move that point closer to the eyes.
Diminished tear secretion in many older patients, especially postmenopausal women, may lead to dryness of the eyes, which can cause irritation and discomfort. This condition may endanger the intactness of the corneal surface. The treatment consists mainly in substitution therapy, with artificial tears instilled at frequent intervals.
The corneal endothelium often undergoes degenerative changes with aging. Because these cells seldom proliferate during adult life, the cell population is decreased. This may leave an irregular surface on the anterior ...