Optic disc planimetry, corneal hysteresis, central corneal thickness and intraocular pressure as risk factors for glaucoma – Accepted Manuscript

Abstract: Purpose: To determine whether corneal hysteresis and central corneal thickness are independent risk factors for glaucoma.Design: This was a cross-sectional population based cohort study.Methods: Associations were tested between corneal hysteresis, measured in 1754 population-based subjects from the TwinsUK cohort, and glaucoma-related endophenotypes, including intraocular pressure (IOP), vertical cup to disc ratio, optic disc area and optic disc cup area. Corneal hysteresis, IOP and Central Corneal Thickness (CCT) were measured using the Ocular Response Analyser (ORA-Reichert® Buffalo, NY). Optic disc photographs were analysed using the Stereo DX program. Multivariable linear regression analysis was performed using STATA software.Results: Data was available on 1645 individuals. Multiple regression analysis showed corneal hysteresis to be significantly negatively associated with age (beta coefficient = -0.03, p <0.00005) and IOP (beta coefficient = -0.06, p< 0.00005). Corneal hysteresis was also found to be associated with CCT (beta coefficient =0.02, p<0.0005). There was no significant association between corneal hysteresis and optic disc area (p=0.6), cup area (p=0.77), vertical cup to disc ratio (p=0.51), or spherical equivalent (p=0.08). CCT was also found to be significantly associated with IOP (beta coefficient =3.3, p<0.0005) and corneal hysteresis (beta coefficient = 9.4, p<0.0005), but not with age (p=0.59 or spherical equivalent (p=0.16).Conclusion: In this large cohort of healthy British twins, we found no relationship between corneal hysteresis or CCT and quantitative measures of optic disc cupping, suggesting that corneal hysteresis and CCT are not independent risk factors for glaucoma.