Corneal Hysteresis And Beta-zone Parapapillary Atrophy

Abstract

Purpose: : Eyes with ß-zone parapapillary atrophy (βPPA) are at increased risk of glaucoma progression. Eyes with glaucoma have lower corneal hysteresis (CH) than eyes without, and in asymmetric glaucoma, lower CH is associated with the worse eye independently of its effect on IOP measurement. We sought a relationship between CH and βPPA.

Methods: : Consecutive, eligible glaucoma patients seen in a glaucoma referral practice were enrolled in this prospective study. We included patients aged 18-90 years with disc photographs within 12 months of the study visit. Exclusion criteria included history of ocular surgery other than clear corneal phacoemulsification, myopia >6 diopters, contact lens use and corneal abnormality. CH was measured using the Ocular Response Analyzer (Reichert, Inc., Buffalo, NY). Disc photos were evaluated by a single masked examiner for βPPA. Data was analyzed using Medcalc software (Mariakerke, Belgium).

Results: : We enrolled 99 patients (mean ± SD age 67.6 ± 13.8 years; 45 men, 54 women). Univariate analysis showed no statistically significant difference in CH between eyes with and without βPPA (8.70±1.57 vs. 8.10±1.95 mmHg, respectively, p=0.11). There were no differences in corneal resistance factor (CRF) (p=0.47), central corneal thickness (CCT) (p=0.11), ORA wave score (p=0.23), age (p=0.23), gender (p=0.40), IOP (p=0.86) or visual field mean deviation (VFMD) (p=0.45). Eyes with βPPA had greater myopia (-1.50±2.11 vs. -0.22±1.79 diopters, p=0.003). Multivariate analysis adjusting for age, spherical equivalent, VF MD, and wave score showed no significant difference in CH between eyes with and without βPPA (p=0.38). Eyes with asymmetric βPPA also showed no significant difference in CH (9.00±1.17 vs. 9.10±1.43 mmHg, p=0.69).

Conclusions: : There is no significant difference in CH between eyes with and without βPPA or between fellow eyes with asymmetric βPPA.

Keywords: optic disc • cornea: clinical science