Association between corneal biomechanical properties and glaucoma severity.

PURPOSE

To investigate the association between corneal biomechanical parameters using the Ocular Response Analyzer (ORA) and glaucoma severity.

DESIGN

Observational cross-sectional study.

METHODS

Two hundred ninety-nine eyes of 191 patients with confirmed or suspect glaucoma were recruited at the University of California, San Diego. Corneal hysteresis (CH) and corneal resistance factor (CRF) were obtained from all participants. Standard automated perimetry was done using the 24-2 Swedish Interactive Threshold Algorithm. Retinal nerve fiber layer (RNFL) thickness measurements were obtained using GDx ECC and spectral-domain optical coherence tomography (SD-OCT). The association between ORA parameters and disease severity was evaluated using univariable and multivariable regression models.

RESULTS

CH and CRF were both positively associated with mean defect (MD) (R(2) = 0.03; P < .01 and R(2) = 0.10; P < .01, respectively). In multivariable analysis, the association between CRF and MD remained significant while CH to MD did not (P < .01 and P = .77). In the GDx ECC subgroup (204 eyes), there was a weak association between CH and CRF and average RNFL thickness (R(2) = 0.07; P < .01 and R(2) = 0.05; P < .01, respectively), which was not observed in the SD-OCT subgroup (146 eyes) (R(2) = 0.01; P = .30 and R(2) = 0.01; P = .21). After adjusting for central corneal thickness, age, and axial length, the relationship of CH and CRF to RNFL thickness no longer reached statistical significance.

CONCLUSIONS

The current study found only a weak relationship between corneal biomechanical parameters and measures of structural and functional damage in glaucoma.