A longitudinal study of body mass index and lens opacities

OBJECTIVE: The purpose of the study was to determine whether body mass index (BMI) is an independent risk factor for the development of nuclear, cortical, or posterior subcapsular lens opacities. DESIGN: A cohort study. PARTICIPANTS AND METHODS: Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Data from the Framingham Heart Study, including weight measurements collected biennially from 1948, were used to examine associations between BMI (mean BMI across examinations, slope of BMI over time, and fluctuations in BMI) and the development of lens opacities. This analysis included 714 individuals, aged 52-80 years, who were free of lens opacities at the first eye examination. MAIN OUTCOME MEASURES: Development of nuclear, cortical, and posterior subcapsular lens opacities. RESULTS: A total of 444 persons developed lens opacities during the approximately 13 years between eye examinations. In logistic regression analyses that controlled for age, sex, education, diabetes, and smoking, the risk of developing cortical opacity increased with higher BMI at the time of the first eye examination (P = 0.002). Risk of cortical opacities also increased, at a borderline level of significance, with higher average BMI (P = 0.09) across examinations and increasing BMI levels over time (P = 0.10). There was a strong association between increasing BMI over time and the development of posterior subcapsular lens opacities (P = 0.002). No associations were found for nuclear lens opacities. CONCLUSIONS: Although the mechanism explaining the association is unclear, these findings suggest that BMI, a potentially modifiable characteristic, is associated with the development of cortical and posterior subcapsular lens opacities.