Purpose:
Central corneal thickness (CCT) and corneal hysteresis (CH), a marker of corneal viscoelasticity, have been identified as risk factors for glaucoma and its progression.1 While glaucoma prevalence varies by race, in the Ocular Hypertension Treatment Study a thin CCT and optic disc cupping accounted for an increased risk of POAG in blacks.2 We evaluated relationships between CH and glaucoma in a population of blacks, whites and Hispanics.
Methods:
556 eyes (302 consecutive patients) underwent comprehensive ophthalmic evaluation including intraocular pressure (IOP) measurement by Goldmann applanation, CH and corneal compensated IOP (IOPcc, measured by the ocular response analyzer; Reichert) , CCT by ultrasonic pachymetry (DGH-500 Pachette; DGH Technologies), and mean deviation (MD) by 24-2 SITA standard automatic perimetry (HFA II, Carl Zeiss Meditec). Associations between variables were assessed using simple and multiple linear regression.
Results:
CH and CCT were significantly different among 166 black, 196 Hispanic and 195 white patients (p<0.001). The mean CH (mm Hg) and CCT (microns) was 8.4 and 530.5 in blacks, 9.6 and 544.5 in Hispanics and 9.7 and 551.6 in whites. These differences remained significant after controlling for age, sex and MD(p<0.001). CH, but not CCT, was associated with worsening MD (p<0.05). There was evidence of statistically significant effect modification, with the magnitude of change of MD as a function of CH greatest among whites and least among Hispanics (p<0.05; Figure 1). The predicted change in MD (dB) with a one standard deviation increase of CH (2.64) was 1.78 for whites, 0.83 for blacks and 0.31 for Hispanics.
Conclusions:
CH was significantly different among whites, blacks and Hispanics. Across races, lower CH was associated with a worsening MD. This association appears greatest in whites and lowest among Hispanics.1: Congdon NG, et al. Am J Ophthalmol. 2006 May;141:868-75.2: Gordon MO, et al. Arch Ophthalmol. 2002 Jun;120:714-20.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment