Myopia shows significant familial aggregation in an older, well–defined population

Abstract

Abstract: : Purpose: To determine the heritability of refractive error and the familial aggregation of myopia in an older population. Methods: We recruited 759 siblings (mean age 73.4 years) in 241 families from the Salisbury Eye Evaluation Study in Eastern Maryland. Refractive error was determined by non–cycloplegic subjective refraction (if BCVA was <=20/40) or lensometry (if BCVA was >20/40 with spectacles). Participants were considered plano if uncorrected BCVA was >20/40 and pre–operative refraction from medical records was used for pseudophakic subjects. Heritability of refractive error was calculated using multivariate linear regression and was estimated as twice the residual between–sibling correlation after adjusting for age, gender and race. Logistic regression models were utilized to estimate the odds ratio (OR) of myopia given a myopic sibling relative to having a non–myopic sibling. Results: The estimated heritability of refractive error was 61% (95%CI: 34–88%) in this population. The age–, race– and sex– adjusted ORs for four different cutoffs for myopia (–0.50, –1.00, –1.50 and –2.00D) all fell between 2.25 (95%CI: 1.31–3.87) and 3.00 (95%CI: 1.56–5.79). Neither race nor gender were significantly associated with an increased risk for myopia. Conclusions: Refractive error and myopia are highly heritable in this elderly population. Estimates of the odds for myopia associated with having an affected sibling are robust over a range of myopia definitions.

Keywords: myopia • genetics • aging