Influence of Refractive Error on Optic Disc Topographic Parameters: The Singapore Malay Eye Study

Abstract

To examine the relationship between refractive error and optic disc topographic parameters and retinal nerve fiber layer (RNFL) thickness. Population-based cross-sectional study. All 3,280 (78.7% response rate) persons of Asian Malay ethnicity 40 to 80 years of age underwent a standardized interview, ocular examinations, and optic disc imaging with the Heidelberg Retina Tomography II (HRT; Heidelberg Engineering). Associations between spherical equivalent (SE) and HRT parameters were evaluated by partial correlation analysis. There were 2,457 (74.9%) right eyes with good-quality HRT images for analyses. When compared with emmetropic eyes, highly myopic eyes (SE < -6.0 diopters) had greater disc area, rim area, rim volume, whereas hyperopic eyes (SE > 0.5 diopters) had significantly smaller disc area, rim area, and cross-sectional RNFL area (all P < .005). In partial correlation after adjustment for age, sex, body mass index, intraocular pressure, and optic disc area, increase of SE (toward hyperopia) was related significantly with greater cup area (partial correlation coefficient, r = 0.058; P = .004) and cup-to-disc area ratio (r = 0.058; P = .004) and with smaller optic disc area (r = -0.058; P = .004), rim area (r = 0.058; P = .004), and rim volume (r = -0.091; P < .001). This population-based study shows that refractive error is significantly (but weakly) associated with HRT parameters of disc area, cup area, rim area, cup-to-disc area ratio, and rim volume. The clinical significance of these associations need to be determined in further studies.