Abstract
purpose. To describe the relationship of refractive errors to the 10-year incidence of age-related maculopathy (ARM) in a defined white population.
methods. Persons aged 43 to 86 years of age in Beaver Dam, Wisconsin, were invited for a baseline examination from 1988 through 1990, and follow-up examinations 5 and 10 years later (n = 3684). Refraction was measured at baseline, with myopia defined as a spherical equivalent of −1.00 D or less, emmetropia as −0.75 to +0.75 D and hyperopia as +1.00 D or more. At each examination, signs of ARM were ascertained from grading stereoscopic color fundus photographs based on a standard protocol. The association between baseline refractive status and the 10-year incidence and progression of ARM was analyzed.
results. The 10-year cumulative incidence for early ARM was 7.1%, 7.7%, and 11.7%, in eyes with myopia, emmetropia, and hyperopia, respectively. The corresponding 10-year cumulative incidence for late ARM was 0.3%, 0.8%, and 2.2%. When age was controlled for, there was no association between myopia and incident early (relative risk [RR] 1.0, 95% confidence interval [CI], 0.7–1.3) and late (RR 0.5, 95% CI, 0.2–1.5) ARM. Similarly, after controlling for age, hyperopia was not associated with incident early (RR 0.9, 95% CI, 0.7–1.1) or late (RR 1.2, 95% CI, 0.6–2.3) ARM.
conclusions. These prospective population-based data provide no evidence of an association between refractive errors and risk of ARM.
Age-related maculopathy (ARM) is the leading cause of irreversible blindness in people 65 years of age and older.
1 Identifying possible risk factors for ARM is an important goal in ocular research, because it may offer insights into the pathogenesis of ARM. An association between hyperopia and risk of ARM has been reported in several case–control studies.
2 3 4 5 6 7 Most recently, the Age-Related Eye Disease Study (AREDS) found that people 60 to 80 years or age with hyperopia were 1.3 times (95% confidence interval [CI], 1.0–1.6) as likely to have large drusen and 2.3 times (95% CI, 1.7–3.2) as likely to have exudative ARM as persons who had myopia.
7 However, population-based studies have not found a consistent association between either hyperopia or myopia and ARM.
8 9 10 11 In the National Health and Nutrition Examination Survey, the prevalence of ARM was reportedly higher in persons with hyperopia than in those with emmetropia.
8 In contrast, a population-based study in the United Kingdom found an association between myopia and ARM.
9 However, these studies made no distinction between different severities of refractive error and different forms of ARM. In the Blue Mountains Eye Study in Australia, the only study to evaluate the specific association of increasing severities of myopia and hyperopia with early and late ARM, a weak association was reported between hyperopia and early ARM.
11 Using the average of the refraction in the right and left eyes to define the refractive status of an individual, the investigators showed that persons with moderate to high hyperopia (greater than +3.00 D) were more likely to have prevalent early ARM than persons with emmetropia (odds ratio, 2.0; 95% CI, 1.2–3,4) although this association was substantially weaker in analyses that combined data from both eyes (odds ratio, 1.3; 95% CI, 0.9–1.9).
Regardless, existing studies are cross sectional. Few prospective data are available that evaluate whether refractive errors are risk factors for ARM. In the Beaver Dam Eye Study, we did not find a significant association between hyperopia or myopia and the 5-year incidence of ARM, although the small sample of cases of incident ARM limited the power to detect associations.
12 The purpose of the present study is to examine the relationship between refractive errors and the 10-year incidence of early and late ARM in the Beaver Dam population.