Have you ever watched middle-aged people try to read something that is right in front of them? If they do not already wear glasses or contact lenses, they typically move the material farther away so that they can see it clearly. This change in vision is one of the first noticeable signs of aging, along with the wrinkles and gray hair we considered earlier. Because we rely extensively on sight in almost every aspect of our waking life, its normative, age – related changes have profound and pervasive effects on people’s everyday lives, especially feelings of sadness and loss of enjoyment of life (Mojon-Azzi, Sousa-Poza, & Mojon, 2008).
How does eyesight change with age? The major changes are best understood by grouping them into two classes: changes in the structures of the eye, which begin in the 40s, and changes in the retina, which begin in the 50s (Mojon-Azzi et al., 2008).
Structural Changes in the Eye. Two major kinds of age-related structural changes occur in the eye. One is a decrease in the amount of light that passes through the eye, resulting in the need for more light to do tasks such as reading. As you might suspect, this change is one reason why older adults do not see as well in the dark, which may account in part for their reluctance to go places at night. One possible logical response to the need for more light would be to increase illumination levels in general. However, this solution does not work in
all situations because we also become increasingly sensitive to glare (Aldwin & Gilmer, 2004). In addition, our ability to adjust to changes in illumination, called adaptation, declines. Going from outside into a darkened movie theater involves dark adaptation; going back outside involves light adaptation. Research indicates that the time it takes for both types of adaptation increases with age (Charman, 2008). These changes are especially important for older drivers, who have more difficulty seeing after confronting the headlights of an oncoming car.
The other key structural changes involve the lens (Charman, 2008). As we grow older, the lens becomes more yellow, causing poorer color discrimination in the green-blue-violet end of the spectrum. Also, the lens’s ability to adjust and focus declines as the muscles around it stiffen. This is what causes difficulty in seeing close objects clearly (called presbyopia), necessitating either longer arms or corrective lenses. To complicate matters further, the time our eyes need to change focus from near to far (or vice versa) increases. This also poses a major problem in driving. Because drivers are constantly changing their focus from the instrument panel to other autos and signs on the highway, older drivers may miss important information because of their slower refocusing time.
Besides these normative structural changes, some people experience diseases caused by abnormal structural changes. First, opaque spots called cataracts may develop on the lens, which limits the amount of
© iStockphoto. com/iofoto
Older drivers may miss information due to changes in vision.
light transmitted. Cataracts often are treated by surgical removal and use of corrective lenses. Second, the fluid in the eye may not drain properly, causing very high pressure; this condition, called glaucoma, can cause internal damage and loss of vision. Glaucoma, a fairly common disease in middle and late adulthood, is usually treated with eye drops.
Retinal Changes. The second major family of changes in vision result from changes in the retina. The retina lines approximately two thirds of the interior of the eye. The specialized receptor cells in vision, the rods and the cones, are contained in the retina. They are most densely packed toward the rear and especially at the focal point of vision, a region called the macula. At the center of the macula is the fovea, where incoming light is focused for maximum acuity, as when you are reading. With increasing age the probability of degeneration of the macula increases (Kupfer, 1995). Macular degeneration involves the progressive and irreversible destruction of receptors from any of a number of causes. This disease results in the loss of the ability to see details; for example, reading is extremely difficult, and television often is reduced to a blur. Roughly 1 in 5 people over age 75, especially smokers and European American women, have macular degeneration, making it the leading cause of functional blindness in older adults.
A second age-related retinal disease is a byproduct of diabetes, a chronic disease described in detail in Chapter 4. Diabetes is accompanied by accelerated aging of the arteries, with blindness being one of the more serious side effects. Diabetic retinopathy, as this condition is called, can involve fluid retention in the macula, detachment of the retina, hemorrhage, and aneurysms (Kupfer, 1995). Because it takes many years to develop, diabetic retinopathy is more common among people who developed diabetes early in life.
The combined effects of the structural changes in the eye create two other types of changes. First, the ability to see detail and to discriminate different visual patterns, called acuity, declines steadily between ages 20 and 60, with a more rapid decline thereafter. Loss of acuity is especially noticeable at low light levels (Charman, 2008).
Physical Changes 79
Psychological Effects of Visual Changes. Clearly, age – related changes in vision affect every aspect of older adults’ daily lives and their well-being (Mojon-Azzi et al., 2008). Research indicates that there can be as much as a sixfold decline in visual ability in everyday situations, depending on the skill needed (Schneider, 1996). Imagine the problems people experience performing tasks that most young adults take for granted, such as reading a book, watching television, reading grocery labels, or driving a car. Fortunately, some of the universal changes, such as presbyopia, can be corrected easily through glasses or contacts. Surgery to correct cataracts is now routine. The diseased lens is removed and an artificial one is inserted in an outpatient procedure that usually lasts about 30 minutes, with little discomfort. Patients usually resume their normal activities in less than a week and report much improved daily lives.
If you want to provide environmental support for older adults, taking their vision changes into account, you need to think through your intervention strategies carefully. For example, simply making the environment brighter may not be the answer. For increased illumination to be beneficial, surrounding surfaces must not increase glare. Using flat latex paint rather than glossy enamel and avoiding highly polished floors are two ways to make environments “older adult-friendly" There should be high contrast between the background and operational information on dials and controls, such as on stoves and radios. Older adults may also have trouble seeing some fine facial details which may lead them to decrease their social contacts for fear of not recognizing someone.
Among people who have experienced substantial vision loss, it appears that conscientiousness predicts how they handle their vision loss. People high in conscientiousness perceive vision loss as a challenge to be overcome. As a result, they are more willing to invest the time and energy necessary to complete tasks and to learn alternative strategies (Casten et al.,
1999) . Visual problems also increase vulnerability to falls because the person may be unable to see hazards in his or her path or to judge distance very well. Thus, part of Bertha’s concern about falling may be
caused by changes in her ability to tell where the next step is or to see hazards along the sidewalk.