If they're compromised in their low-contrast visual acuity, that could pose a problem to them when they try to make up with vision the information lost to hearing. The investigators cite evidence that dual sensory loss can have greater effects on depression, cognitive function, and quality of life compared with sensory hearing or vision loss alone. Although the study has substantial design flaws, it draws attention to the fact that older adults frequently have sensory deficits that may get overlooked, commented William J. Hall, MD, Fine Professor of Medicine at the Center for Healthy Aging at the University of Rochester School of Medicine in New York. "All healthcare providers who deal with older people need to be aware of the potential for multiple morbidities at the same time. Frankly, what I find is that we commonly miss hearing loss in older people," said Dr. Hall . However, he questioned the investigators' choice to control for age by 5- to 8-year groups rather than as a continuum, and he noted that it would be a mistake to infer from the data that a single mechanism might be responsible for both hearing and vision loss. Johanna M. Seddo, MD, ScM, director of the Ophthalmic Epidemiology and Genetics Service at the New England Eye Center at Tufts Medical Center in Boston, Massachusetts, agrees with Dr. Hall that the authors should have looked at age as a continuous variable. She also noted that the study sample was small, with only 57 of the 446 participants having moderate hearing loss. "It might also have been helpful if the authors had looked at cardiovascular risk factors [other than stroke]. For example, smoking has been shown to be a risk factor for hearing loss in some studies, and we know that it's related to diseases that cause visual loss, both macular degeneration and cataract," she said. Dr. Schneck and colleagues looked at a cohort of older adults enrolled in a longitudinal study of vision and function in Marin County, California. The participants were screened for visual function with both high-contrast and low-contrast visual acuity tests. Moderate visual impairment was defined as binocular high-contrast visual acuity worse than 0.54 logarithm of the minimum angle of resolution, equivalent to 6/21 or 20/70 or worse on a Snellen chart. The authors defined moderate hearing impairment as the inability to hear pure tones presented twice to each ear by an audioscope set to deliver 500-, 2000-, and 4000-Hz frequencies at 40 decibels. As might be expected, the investigators found that prevalence of hearing loss, visual impairment, and dual sensory deficits increased with age. For example, only 1.6% of 67- to 74-year-olds had moderate hearing impairment, compared with 32.7% of those aged 85 years and older. Similarly, although no participants in the 67- to 74-year-old age range met the vision impairment criteria, 19.1% of those aged 85 and up had at least moderate vision loss. No participants younger than age 75 had dual hearing and vision loss, compared with less than 1% of those aged 75 to 79 and 11.8% of those aged 85 and older. In multivariate logistic regression analysis controlling for age, hearing impairment was significantly positively associated with a history of cataract surgery (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.01 - 3.85; P < .05) and self-reported stroke (OR, 2.69; 95% CI, 1.18 - 6.15; P < .05) and was negatively associated with a history of glaucoma (OR, 0.37; 95% CI, 0.15 - 0.88; P < .05). The overall rate of moderate visual impairment was 5.4%, and the rate of moderate, bilateral hearing impairment was 12.8%, suggesting that the conditions are linked in at least some participants, the investigators say. "If vision and hearing impairments were independent, the probability of having both would be the product of the separate impairment probabilities. In this case, we would expect dual sensory loss in 0.7% of people. In fact, the prevalence of dual sensory loss was over four times higher (3.1%), indicating that the two kinds of impairment are associated," they write. The vision measures that were significantly associated with hearing loss were overall low contrast (10%) acuity (OR, 1.50; 95% CI, 1.02 - 2.22; P < .05), low contrast acuity at low luminance (OR, 1.46; 95% CI, 1.07 - 1.98; P < .05), and low contrast and acuity in glare (OR, 1.40; 95% CI, 1.02 - 1.91; P < .05). "For any of these three measures, those who perform poorly were 40-50% more likely to have moderate bilateral hearing loss than those who scored well on that measure," the investigators write. Normal or high-contrast acuity measures were not significantly associated with hearing loss, however.
