Both vision and hearing impairment increase dramatically with advancing age. The Baltimore Eye Survey (Tielsch et al., 1990) reported crude prevalence rates of visual impairment (acuity less than 20/60 in the better eye) of 0.6 percent for Whites and 1.0 percent for Blacks age 40 to 49 years and 2.1 percent for Whites and 6.0 percent for Blacks age 70 to 79 years. Data from three communities in the Established Populations for Epidemiologic Studies of the Elderly (EPESE) indicate a vision impairment rate of 8.2 percent for persons age 71 to 74 years, increasing to 22.2 percent for those age 80 to 84 years (Salive et al., 1992). Prevalence rates based on self-report, such as the data from the National Health Interview Survey (NHIS), are comparable (Havlik, 1986). There are few recent data on objectively determined hearing loss, but data based on self-report indicate that hearing disorders are among the five most common chronic conditions in the U.S. population age 65 years and older (Collins, 1993). Twenty-six percent of adults age 65 to 74 years report deafness or other hearing impairment, and the prevalence increases to 37 percent in those 75 years and older.
Several population based studies have found that sensory impairment is strongly associated with physical disability among older adults. Cross-sectional analyses of survey data from the NHIS (Havlik, 1986), the Massachusetts Health Care Panel Study (MHCPS; Jette and Branch, 1985), and the Longitudinal Study of Aging (LSOA; Rudberg et al., 1993) showed that persons age 65 years and older who reported visual impairment were more likely to have difficulty with activities of daily living (ADLs). Hearing impairment was not significantly or independently associated with disability in the MHCPS or LSOA. Several European studies (Bergman and Sjostrand, 1992; Carabellese et al., 1993; Hakkinen, 1984; Thompson et al., 1989) concluded that visual impairment measured by visual acuity was associated with a lack of self-sufficiency in the home and difficulty with daily tasks. Hearing impairment, assessed with a speech recognition task, was also associated with decreased self-sufficiency in the Italian study (Carabellese et al., 1993). Finally, visual impairment (Dunn et al., 1992; Gerson et al., 1989; Grisso et al., 1991) and hearing impairment (Dunn et al., 1992; Gerson et al., 1989) were both significant risk factors for balance problems and falls, especially for older women.
Longitudinal studies have had less consistent findings. A 2-year followup of participants in the LSOA showed no association between visual impairment-defined as the presence of an eye disease or "trouble seeing"-and the progression of physical disability (Harris et al., 1989). However, data from a 4-year followup of the LSOA showed an increased risk for progression of disability in participants with visual impairment, independent of other chronic conditions. A 5-year followup of the MHCPS cohort found that change in ability to perform daily activities was not related to self-reported change in vision. These discrepancies may be due, in part, to the use of self-report rather than objective measures of visual impairment. Among persons initially free of mobility or ADL limitations in the EPESE population, severely impaired visual acuity was associated with a threefold higher incidence of mobility and ADL limitations over 15 months, independent of diabetes and stroke (Salive et al., 1994).
In the Women's Health and Aging Study (WHAS), both vision and hearing were assessed by questionnaire and using objective tests. This chapter describes the test procedures and provides the distribution of the test results and questionnaire responses as they relate to age and disability status.
As part of a comprehensive medical questionnaire, all participants were asked about current and previous eye conditions. Use of eyeglasses and ability to see well enough to perform several everyday visual tasks was also queried. The questions are listed in Tables 14.1 and 14.2.
Visual acuity was tested with the Goodlite Portable Eye Chart (Model A with LD-10 translucent acuity card). The Goodlite Chart is small and lightweight and contains its own source of standardized illumination. The LD-10 chart uses the Sloan letter set, which has been recommended by the National Academy of Sciences/National Research Council Committee on Vision (National Academy of Sciences, 1980). The test was administered in a darkened room with the participant wearing her customary glasses used for viewing distant objects. If she used bifocals or trifocals, the participant was instructed to view through the segment used for distance vision (usually the top). All testing was done with both eyes together, that is, binocularly. The test distance was initially set at 10 feet, but if the participant was unable to read the largest letters at this distance, the chart was placed 5 feet away and, if necessary, 2.5 feet away. The acuity test was administered in a "forced-choice" fashion; that is, the participant was instructed to provide a letter response for each target and to guess if she was uncertain. Testing proceeded until at least 75 percent of the targets on a single row were missed. This forced-choice procedure has been demonstrated to yield more reliable data than procedures that allow the participant to decide when to terminate the test (Rubin, 1988). In scoring the acuity test, credit was given for each letter correctly identified (Bailey et al., 1991). Although the letter size decreases on each line by a constant 0.1 log units (26 percent) from the preceding line, the number of letters per line increases down the chart in a variable manner. Therefore, the credit awarded for each letter was 0.1 log units divided by the number of letters on that line. The total score was given as an acuity measure in logMAR (log10 minimum angle of resolution) units. All analyses were performed with logMAR units, but the logMAR values were converted to the more familiar Snellen fraction (e.g., 20/20) for reporting purposes. The test is capable of measuring acuities ranging from 1.4 logMAR (20/500) for zero letters correct at 2.5 feet to 0.9 logMAR (20/16) for all letters correct at 10 feet.
Table 14.1 shows the percentage of participants reporting a history of ocular conditions. Cataract was the most common condition, but the question did not separate those with current cataract from those who had undergone cataract surgery before the study. Cataract, macular degeneration, and eye injury were reported by a larger percentage of participants in the age group 85 years and older than in the younger age groups. Prevalence of glaucoma and diabetic retinopathy did not increase with age.
The vast majority of participants (95 percent) reported wearing eyeglasses at least sometimes or for particular tasks such as reading or driving, and 82 percent wore them for the vision test. Table 14.2 lists the percentage of participants who reported difficulty with everyday visual tasks. The most frequently reported problem was blurry vision (37 percent) followed by difficulty reading a newspaper (13 percent). Difficulty reading a newspaper was more common among participants who received help with ADLs (22 percent) than among those with lower levels of disability (10 to 11 percent).
Visual acuity scores are presented in Table 14.3. Twenty-three percent of participants had 20/20 acuity or better, while fewer than 2 percent would be considered legally blind (acuity less than 20/200). Using the World Health Organization definition of visual impairment-visual acuity less than 20/60-8 percent would be considered at least moderately visually impaired. This percentage increased with age and was higher in those receiving help with ADLs than in the remainder of the cohort.
A brief hearing questionnaire was administered, including items from the Hearing Handicap Inventory for the Elderly-Screening Version (Ventry and Weinstein, 1982). Items included in the hearing questionnaire are listed in Table 14.4. Participants were also asked about their use of hearing aids.
Hearing loss was assessed with the Welch Allyn Audioscope3. The instrument combines an otoscope with a handheld audiometer and has been shown to provide accurate and efficient early detection of hearing loss (Lichtenstein et al., 1988). The Audioscope3 provides screening at 1,000, 2,000, 4,000, and 500 Hz, respectively, with a 40 dB tone. To the extent possible, the test was administered in a quiet area of the participant's home. The Audioscope3 was fitted with one of three ear speculae, the largest that would fit comfortably into the ear canal, and the built-in otoscope was used to look at the tympanic membrane. The presence of cerumen that blocked the tympanic membrane was noted.
Before testing, a 1,000 Hz practice tone was delivered at 60 dB. This was followed by four screening tests, two for each ear, alternately, beginning with the left ear. The participant was instructed to raise her hand each time she heard a tone and put her hand down when the tone stopped. The test was scored as pass/fail at each tone tested; the participant had to fail both trials to fail that frequency for a given ear. Hearing impairment was defined based on the criteria of Lichtenstein et al. (1988).
Results from the hearing questionnaire are shown in Table 14.4. Nine percent of the participants used a hearing aid, with a dramatic increase with age, from 5 percent of those age 65 to 74 years to 23 percent of those age 85 years and older. While 9 percent of respondents reported that hearing difficulty hampered their personal or social life, 46 to 51 percent reported difficulty with specific tasks such as hearing conversation when there is a radio or TV on in the room or when the person is speaking in a whisper.
The prevalence of hearing impairment, shown in Table 14.5, was much higher than visual impairment. Overall, 39 percent of participants were classified as hearing impaired, with a 40 dB hearing loss at 1,000 or 2,000 Hz in both ears or at 1,000 and 2,000 Hz in a single ear, and 33 percent were bilaterally impaired. The percentages increased markedly with age: 72 percent of women age 85 years and older showed hearing impairment, and 67 percent showed bilateral hearing impairment. Because of the strong age gradient in rates of hearing impairment, disability-specific rates of impairment were age-adjusted. After adjusting for age, hearing impairment was not strongly associated with disability status.
The prevalence of vision and hearing impairments was considerable, as would be expected among older women with moderate to severe functional limitations and disability. In this cross-sectional examination, impaired vision appeared to be related to both age and disability, while hearing impairment was related primarily to age. In comparing the frequency of vision and hearing impairment from this study with that reported in previous studies, it should be noted that visual acuity was measured binocularly with glasses and hearing impairment was measured without a hearing aid.
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