Changes in Corneal Biomechanics and Glaucomatous Visual Field Loss.

PRECIS A lower baseline corneal hysteresis and a decrease in corneal resistance factor over time are associated with higher risk of visual field progression in glaucomatous and glaucoma suspect eyes. PURPOSE To investigate the longitudinal change in corneal resistance factor (CRF) and cornea hysteresis (CH) as risk factors for visual field progression. METHODS In this prospective observational cohort study, seventy-two eyes of 48 glaucoma or glaucoma suspect patients were followed for an average of 4.5 years. Baseline and follow-up CH and CRF measurements were performed with the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments Inc, Depew, New York, USA). Evaluation of rates of visual field change during follow-up was performed using visual field mean deviation (MD). Univariable and multivariable linear mixed models assessed the relationship of visual field progression with baseline CRF and CH as well as with changes in CRF and CH. RESULTS The mean baseline CH was 9.0 (95% CI 8.6, 9.4) mg Hg and the mean baseline CRF was 9.3 (95% CI 8.8, 9.9) mm Hg. There was no statistically significant difference in average CH and CRF measurements over time. In multivariable modeling adjusting for age, race and mean IOP during follow-up, each 1▒mm Hg lower in baseline CH and 1▒mm Hg decrease in CRF over time were associated with a 0.12 (P=0.042)) and 0.14▒dB/year (P=0.007) faster rate of visual field MD loss, respectively. Similar findings were found in glaucoma eyes but not found in glaucoma suspect eyes. CONCLUSION Visual field progression was associated with a lower baseline CH and a decrease in CRF over time. Assessment of corneal resistance and elasticity at baseline and during follow-up examinations should be considered to identify those eyes at highest risk of visual field progression.