Visual Functioning and Aging Fall 2011

Social Gerontology: A Multidisciplinary Perspective (9th Edition)

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Visual Functioning and Aging Normal Age-related Changes and Pathological Conditions
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Sensory Loss and Adaptation Aging is related to measurable effects in all body parts, including the five senses. Sensory loss of any kind, if not corrected or minimized, can adversely affect an older individual’s health and general well-being. There are individual differences in the speed and the degree to which one’s sensory function declines with aging. Genetics, one’s lifestyle, and environment all play a role.
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Vision The visual system changes in many ways as the human body ages. Many visual changes are considered “normal aging” while others are disease-related changes that further impair vision. Most elderly people do not distinguish normal age-related visual change from disease-related vision loss, so many do not seek professional help.
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Anatomy of the Human Eye
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Anatomical Changes in the Eye Each of the age-related anatomical changes in the visual system has a corresponding impact on visual function. Anatomical changes in the older visual system include changes in the cornea the lens the pupil the vitreous humor the retina, and the retinal pigment epithelium.
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The Cornea The cornea, or the fixed lens, is the first lens that focuses light. It is the most powerful lens in the eye, and is responsible for focusing most of the incoming light. The cornea does not change shape, but it does thicken and the surface becomes less regular over time. This contributes to the amount of extra light scatter. The thickening also can influence the focusing power of the cornea.
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The Lens (Variable Lens) This is the second lens within the eye, and this lens can adjust its shape to focus incoming light further. This lens begins to change at birth. Cells are not sloughed off from the lens. Instead, over time the tissue becomes more compacted which affects the flexibility of the lens. Adults usually notice this change around the age of 40 years, when the lens can no longer focus on average-sized print at a normal reading distance. This results in changes in visual accommodation.
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Yellowing of the Lens In addition to the increased density of lenticular cells, the chemical composition of the lens also changes with age as proteins are produced in different proportions. These chemical changes cause the lens to yellow over time. This yellowing of the lens reduces its transparency, causing it to become more opaque with time. The yellowing of the lens acts as a filter for shorter wavelengths (which correspond to the blue end of the color spectrum). These colors will appear dull or even grey to older people. Yellowing of the lens is related to age-related changes in color discrimination.
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Pupil The pupil is the opening in the iris inside the eye that allows light to enter.
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