Myopia and the long-term incidence of cataract and cataract surgery: the Blue Mountains Eye Study

Background To assess the association between refractive errors and the 10-year incidence of cataract and cataract surgery. Design Population-based prospective study. Participants Three thousand six hundred fifty-four persons aged 49+ years living in a well-defined geographical region were examined at baseline; 2564 were re-examined after 5 and/or 10 years. Methods Baseline refractive error was measured using autorefraction with subjective refinement. Lens photographs were taken at each visit and assessed using the Wisconsin Cataract Grading System. Main Outcome Measures Long-term incidence of cataract and cataract surgery. Results Compared with emmetropia, high myopia was associated with increased incidence of nuclear cataract (adjusted odds ratio 3.01, 95% confidence intervals 1.35-6.71). Low (odds ratio 1.86, confidence interval 1.03-3.35) and high myopia (odds ratio 7.80, confidence interval 3.51-17.35) were significantly associated with higher incidence of posterior subcapsular cataract. Low, moderate and high myopia were associated with increased incidence of cataract surgery (odds ratio 2.54, confidence interval 1.76-3.68; odds ratio 2.61, confidence interval 1.45-4.69; and odds ratio 4.81, confidence interval 2.33-9.93, respectively). Either any (odds ratio 1.35, confidence interval 1.08-1.69) or moderate hyperopia (odds ratio 1.76, confidence interval 1.32-2.34) was associated with increased incidence of nuclear cataract. Conclusion Our longitudinal study confirms the association between myopia and an increased risk of nuclear and posterior subcapsular cataract. It also suggests that hyperopia may increase the risk of nuclear cataract.