title: Heritability of refractive error and familial aggregation of myopia in an elderly American population.
abstract: OBJECTIVE
  To determine the heritability of refractive error and the familial aggregation of myopia in an older population.
  
  
  METHODS
  Seven hundred fifty-nine siblings (mean age, 73.4 years) in 241 families were recruited from the Salisbury Eye Evaluation (SEE) Study in eastern Maryland. Refractive error was determined by noncycloplegic subjective refraction (if presenting distance visual acuity was < or =20/40) or lensometry (if best corrected visual acuity was >20/40 with spectacles). Participants were considered plano (refractive error of zero) if uncorrected visual acuity was >20/40. Preoperative refraction from medical records was used for pseudophakic subjects. Heritability of refractive error was calculated with multivariate linear regression and was estimated as twice the residual between-sibling correlation after adjusting for age, gender, and race. Logistic regression models were used to estimate the odds ratio (OR) of myopia, given a myopic sibling relative to having a nonmyopic sibling.
  
  
  RESULTS
  The estimated heritability of refractive error was 61% (95% confidence interval [CI]: 34%-88%) in this population. The age-, race-, and sex-adjusted ORs of myopia were 2.65 (95% CI: 1.67-4.19), 2.25 (95% CI: 1.31-3.87), 3.00 (95% CI: 1.56-5.79), and 2.98 (95% CI: 1.51-5.87) for myopia thresholds of -0.50, -1.00, -1.50, and -2.00 D, respectively. Neither race nor gender was significantly associated with an increased risk of myopia.
  
  
  CONCLUSIONS
  Refractive error and myopia are highly heritable in this elderly population.
authors.affiliation: Bloomberg School of Public Health, School of Medicine, Johns Hopkins University, Baltimore, MD, USA. rwojciec@jhsph.edu
authors.forename: Robert
authors.initials: R
authors.lastname: Wojciechowski
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Heidi
authors.initials: H
authors.lastname: Bowie
authors.forename: Beatriz
authors.initials: B
authors.lastname: Munoz
authors.forename: Donna
authors.initials: D
authors.lastname: Gilbert
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044383:Black People / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008396:Maryland / Q000453:epidemiology; D009216:Myopia / Q000453:epidemiology / Q000235:genetics*; D015995:Prevalence; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000453:epidemiology / Q000235:genetics*; D035781:Siblings; D011795:Surveys and Questionnaires; D014792:Visual Acuity; D044465:White People / Q000235:genetics; D001741:Black or African American