26 Upon completion of this chapter, the reader will be able to: • Know changes to the eye, vision, and visual function that accompany aging. • Understand the impact of contrast sensitivity, illumination, and glare on visual acuity and visual function. • Be familiar with the three most common age-associated ocular diseases, their diagnostic features, and treatment. • Understand optical and non-optical methods to enhance visual function. The eye is the window to the soul—and so much more. It is key to maximum functionality. With age, vision and functionality related to vision decline.1,2 This has a major impact on quality of life and independence. Loss of vision is associated with depression, difficulties with activities of daily living and safe driving, as well as increased risk of injury, falls, and medication errors. Surprisingly, visual acuity is not a good predictor of visual ability.2–4 Visual acuity is tested under high-contrast, ideal conditions that rarely exist outside of a doctor’s office. Better predictors are contrast sensitivity, glare sensitivity, and performance under reduced illumination. Performance in these areas declines not only for older adults with visual impairment (visual acuity worse than 20/40) but also for older adults without visual impairment. Deficits worsen when low contrast, reduced illumination, and glare coexist. Treating refractive error and ocular disease is helpful but is not enough. Minimizing functional deficits related to the environmental conditions listed above will maximize function and independence. Success requires a team approach among the patient, family, primary care provider, eye care provider, and an occupational therapist trained in vision rehabilitation. The goal of this chapter is to provide the reader with the tools to easily deliver and coordinate such comprehensive care. The Smith-Kettlewell Institute (SKI) Study evaluated vision and visual function in older adults aged 58 to 85 and older.4 Visual impairment was defined as binocular acuity of 20/40 or worse. Among people age 40 and older, more than 3.6 million are visually impaired. After age 60, 89% of the SKI study patients had no visual acuity impairment. Unfortunately, this percentage declined steadily with increasing age as shown in Table 26-1. Thus, 40% of patients 85 and older had some form of visual impairment. The statistics are even worse for the nursing home population where it is estimated that the degree of legal blindness (visual acuity worse than 20/200) is 15% in those older than age 60 and up to 29% in those older than age 90. This is an increase of 15 times over community-dwelling older adults.1 Such statistics highlight vision loss as the third leading cause of activity of daily living (ADL) impairment.5 More than one half of the conditions that cause visual impairment or blindness in older individuals are surgically treatable or potentially preventable.6 Additionally, one third of older adults with visual impairment improve vision with refraction alone. Thus simply increasing access to eye care would significantly improve vision and function in older Americans. TABLE 26-1 Vision loss and decreased vision function in older adults are related to ocular disease and age-related physiologic changes.1–5,7 Even older patients with good visual acuity (20/40 or better) and no significant ocular disease showed deficits in visual function.4 Visual acuity is tested under maximum contrast (i.e., black target on white background) and illumination with minimal glare. Rarely in life do people operate under these ideal conditions. Real-life vision occurs more commonly under decreased contrast, decreased and changing illumination, and increased glare. Contrast sensitivity is the ability to distinguish an object from its background. A visual acuity chart and most street signs provide high contrast sensitivity whereas camouflage demonstrates low contrast. Measurement of visual function (rather than visual acuity) correlates highly with success in performing many common and essential daily activities.3,8 Standard visual acuity can be measured with a distance and near Snellen chart. Testing the effects of decreased contrast sensitivity, decreased illumination, and increased glare is not practical for the primary care provider, because the equipment necessary for such testing is specialized and is not widely available to primary care providers.3,4 Rather, questioning older patients about their performance under these circumstances is easier. For contrast sensitivity, ask if a patient has much difficulty driving in the rain or seeing on a hazy day. For low illumination, ask if the patient has significantly greater difficulty seeing at dusk and at night. For glare, ask how debilitated the patient is by oncoming headlights, by walking from outside to inside on a sunny day, or by entering a tunnel from daylight. Enhancing visual function requires a team approach among the primary care provider, the eye care provider, and an occupational therapist trained in visual rehabilitation. Eye examination by an optometrist or ophthalmologist is key to providing best-corrected vision with refraction and treatment of visual deficits caused by ocular disease. Despite these efforts, some patients may not be correctable to 20/20. Performance can be enhanced for patients with low vision (worse than 20/70 visual acuity) and for patients with better acuity who have difficulty in certain circumstances or settings. An ideal approach would be to have a home evaluation by a vision rehabilitation specialist. Because this is not readily available for many older adults, a more practical approach educates the primary care provider, the patient, and the patient’s family about simple measures to maximize visual acuity and function.
Visual impairment and eye problems
Visual impairment with age
Prevalence and impact
Age (Years)
Percent without Visual Acuity Impairment
58-69
99
70-74
97
75-79
91
80-84
88
≥85
60
Risk factors and pathophysiology
Differential diagnosis and assessment
Management
Visual impairment and eye problems
