Effect of Corneal Arcus on Central Corneal Thickness, Intraocular Pressure, and Primary Open-angle Glaucoma The Singapore Malay Eye Study

Objectives: To examine the association of corneal arcus with central corneal thickness (CCT), intraocular pressure (IOP), and the prevalence of primary open-angle glaucoma. Methods: This was a population-based cross-sectional study of Malay participants aged 40 to 80 years living in Singapore. Participants underwent a standardized interview and systemic and ocular examinations, including CCT, IOP, and corneal curvature radius measurements. Corneal arcus, assessed using a slitlamp, was defined as gray-white or yellow opacity located near the periphery of the cornea but separated from the limbus by a clear zone. Results: Corneal arcus was found in right eyes among 1747 (57.9%) of 3015 participants. After adjusting for age, sex, and systemic factors, IOP was higher (15.87 vs 14.86 mm Hg, P<.001) and CCT was thinner (540.6 vs 543.4 mu m, P=.03) in eyes with vs without corneal arcus. In multiple linear regression models, eyes with corneal arcus had on average 1.14 mm Hg higher IOP than eyes without corneal arcus. In the presence of corneal arcus, the linear correlations of CCT X IOP and of corneal curvature radius X IOP were altered. The prevalence of ocular hypertension, but not primary open-angle glaucoma, was significantly higher among participants with corneal arcus than among participants without corneal arcus (P=.02). Conclusions: Corneal arcus was associated with higher IOP and lower CCT independent of age, sex, and systemic and ocular factors. Further research is required to investigate the clinical implications of these findings for IOP assessment in eyes with corneal arcus.