General Principles in Older Adults
Vision impairment is relatively rare in people younger than 65 years of age, but its incidence steadily increases to almost 24% of those 80 years and older. Not surprisingly, vision impairment can have a significant impact on a patient’s quality of life. It is associated with social isolation, anxiety, depression and a loss of independence. It can affect balance, leading to more frequent falls, and has been shown to negatively affect physical activity.
The following 3 levels are used to categorize the severity of vision loss*:
Normal vision: Visual acuity ≥20/40
Visual impairment: Visual acuity >20/40 but <20/200
Legal blindness: Acuity ≤20/200 in the better eye, or total visual field <20 degrees
Normal Changes in the Aging Eye
Although not meeting the definition of vision impairment, there are still a number of changes in the aging eye leading to diminished vision. In all adults, the crystalline lens gradually becomes less flexible and less able to change its curvature (accommodate) with age. This results in the condition known as presbyopia, in which patients lose the ability to focus their eyes on near objects. The ability to see well in dim light also becomes diminished in older adults as a result of a combination of decreases in pupil size and progressive increases in the light absorption of the lens. This age-related reduction in retinal illumination is substantial. A typical 60-year-old’s retina receives only about one-third of the light that a typical 20-year-old receives. As a result of the tendency for opacities to form in the aging lens and cornea, older adults are increasingly sensitive to glare caused by scattered light in the eye. Finally, because of neural changes in the retina, there is an age-related reduction in the ability to adapt to sudden changes in illumination.
Starting in the mid-40s, reading glasses may be required to manage presbyopia. Although distance vision remains stable during this time, by the seventh decade and beyond, distance vision also can be reduced because of changes in refractive error. Difficulty with dim lighting and sensitivity to glare may cause problems with driving at night. Dry eye, especially in older women, is also common. Symptoms include a mild foreign-body sensation, burning, small fluctuations in vision, and even (reflexive) tearing because of mild corneal irritation. Table 61–1 includes suggested vision screening tests for older adults.
Table 61–1.Suggested vision screening tests for older adults. |Favorite Table|Download (.pdf) Table 61–1. Suggested vision screening tests for older adults.
|Procedure ||Description ||Causes of Abnormal Findings |
|Visual acuity || || |
|Visual field by confrontation...|