Changes in visual acuity in a population. The Beaver Dam Eye Study.

PURPOSE: To describe the change in visual acuity over a 5-year period in persons participating in a large population-based study.
METHODS: Best-corrected visual acuity was measured, after refraction, with logMAR charts using a modification of the Early Treatment Diabetic Retinopathy Study protocol in 3684 persons living in Beaver Dam, Wisconsin, who ranged in age from 43 to 86 years at the time of a baseline examination from 1988 to 1990, and at a follow-up examination from 1993 to 1995.
RESULTS: The change in the number of letters read correctly over the 5-year period varied from 0.4 +/- 4.9 (mean +/- standard deviation) in people between 43 and 54 years of age to -5.2 +/- 15.4 in people 75 years of age or older at baseline. Over the 5-year period, vision became impaired (20/40 or worse in the better eye) in 2.9% of the population and severely impaired (20/200 or worse in the better eye) in 0.3%. The visual angle doubled in 1.7% of the population, and 2.4% had improved vision. People 75 years of age or older at baseline were 12.5 times (95% confidence interval [Cl], 8.6-18.2; P < 0.001) more likely to have impaired vision, 9.7 times (95% Cl, 5.9-16.0; P < 0.001) more likely to have doubling of the visual angle, and 78 times more likely (95% Cl, 9.9-614.1; P < 0.001) to have severe visual impairment than people younger than 75 years of age at baseline. People 75 years of age or older who were living in nursing homes or group homes were 3.8 times more likely to have impaired vision, 3.3 times more likely to have severely impaired vision, and 5.7 times more likely to have a doubling of the visual angle than those not residing in a nursing home or a group home.
CONCLUSION: These data provide precise population-based estimates of incidence of visual loss over a wide spectrum of ages and show that decreased visual acuity in people 75 years of age is a common finding, especially in those who are in nursing homes or group homes.