Heritability of intraocular pressure and cup–to–disc ratio in a defined, older population

Abstract

Abstract: : Purpose: To investigate the heritability of intraocular pressure (IOP) and cup–to–disc ratio (CDR) in an older population. Methods: Through the population–based Salisbury Eye Evaluation (SEE) study, we recruited 737 siblings (mean age 74.8 years) whose IOP and CDR were measured using the Tonopen and biomicroscopy with a 90D lens, respectively. For participants with a history of pressure–lowering surgery or drug therapy, the IOP for the involved eye was adjusted by an increase of 33%. The heritability of IOP was then calculated using Generalized Estimating Equations (GEE) adjusting for age, gender, race, self–reported diabetes status, history of systemic steroid use, and blood pressure (both systolic and diastolic), while the heritability of CDR was calculated using the same model and adjustments as above plus adjusting for IOP. The heritability was estimated as twice the residual between–sibling correlation. Results: We estimated the heritability to be 0.39 (95% CI: 0.27–0.51) for IOP and 0.59 (95%CI: 0.47–0.72) for CDR in this population. Furthermore, higher systolic blood pressure was significantly associated with higher IOP, while male gender, black race and history of systemic steroid use were significantly associated with a higher CDR. Conclusions: We found CDR to be highly heritable and IOP to be moderately heratable in this elderly population.

Keywords: optic disc • aging • genetics