Familial aggregation of lens opacities: the Framingham Eye Study and the Framingham Offspring Eye Study.

Eye examination data from 1,086 parents examined in the Framingham Eye Study (1973-1975) and 896 offspring examined in the Framingham Offspring Eye Study (1989-1991) were used to study familial associations for nuclear, cortical, and posterior subcapsular lens opacities. Associations between spouses, between parents and offspring, and between siblings were explored. The generalized estimating equations (GEE2) approach to logistic regression was used to simultaneously model risk of lens opacity and familial associations. Specifically, this provided odds ratios, adjusted for age (the age range was 50-74 years) and sex, for the familial associations. For any pair of siblings, the odds of nuclear opacity for one sibling was estimated to more than triple if the other sibling had a nuclear opacity. Similar findings were noted for posterior subcapsular opacity. No significant associations were noted for any of the opacity types between spouses or between parents and offspring. The strong associations between siblings for nuclear and posterior subcapsular opacities suggest there is clustering of lens opacities within families. The clustering may be due to genetic or environmental factors.