Abstract
Purpose::
The prevalence of visual impairment (VI) may be changing over time due to improvements in the treatment of eye diseases and the reduction in risk factors associated with ocular conditions. This study assesses nine-year trends in reported VI in a representative US sample.
Methods::
The National Health Interview Survey (NHIS) is a population-based annual survey of the US non-institutionalized civilian population. Nearly 32,000 adults participated each year in the NHIS from 1997-2005, representing an average annual population of over 205 million community-residing adults 18 years of age and older. Participants were asked, "Do you have any trouble seeing, even when wearing glasses or contact lenses?" (mild/moderate VI), and "Are you blind or unable to see at all? (severe VI). SAS survey procedures were used to compute annual prevalence of VI adjusted for survey weights and design effects. General linear models, weighted by the inverse of the standard error of the prevalence estimate, were used to determine the trend (slope) in the prevalence of VI. The trend was computed for the entire sample and for groups determined by age, gender, race/ethnicity, access to general health care, and visit to an eye doctor in the last year.
Results::
The average annual prevalence of any VI (mild/moderate or severe) was significantly greater in older versus younger adults, females versus males and in non-Hispanic blacks relative to all other race ethnic groups. There were no significant overall trends in the prevalence of mild/moderate, severe, or any VI. However, there was a significant annual decrease of 0.44% (SE=0.14; p=0.001) in the prevalence of any VI for adults ≥80 years of age. Further analysis showed an annual decrease of 0.54% (SE=0.18; p=0.004) for males and 0.39% (SE=0.14; p=0.023 for females in the 80+ age group and annual decreases of 0.87% (SE=0.40; p=0.032) for Hispanics, 0.93% (SE=0.37; p=0.026) for non-Hispanic Blacks; and 0.44% (SE=0.26; p=0.094) for Non-Hispanic Whites. Access to healthcare and a visit to an eye doctor in the last year were not significantly related to VI.
Conclusions::
The downward trend in VI reported in adults age 80 years and over may be due to improvements in the treatment of ocular disease or other secular trends such as improvements in the health/risk factor status of older Americans. Additional monitoring in the coming years is necessary to confirm this encouraging trend and to determine if downward trends eventually extend to younger age groups.
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment