Corneal hysteresis appears to be lower in eyes with primary angle-closure glaucoma

The authors of this prospective study evaluated corneal hysteresis (CH) and IOP measured by the Ocular Response Analyzer (ORA) in Chinese subjects with primary angle-closure glaucoma (PACG), assessed the relationship of these results to central corneal thickness (CCT) and Goldmann applanation tonometry (GAT) measurements, and compared these findings with results in Chinese primary open-angle glaucoma (POAG) subjects and normal controls. This is believed to be the first study of ORA parameters in Asian individuals comparing patients with PACG and POAG and normal subjects. The authors found that corneal hysteresis was lower in eyes with glaucoma. After adjusting for age, sex and IOP measurement by GAT, a persistently lower hysteresis was noted in eyes with PACG compared with eyes of POAG subjects and normal controls.

The authors enrolled 443 subjects (443 eyes) in this study. Consecutive subjects with PACG (131 subjects) and POAG (162 subjects) without prior intraocular surgery were enrolled from glaucoma clinics. One hundred fifty normal subjects were recruited from an ongoing population-based study. One eye of each subject underwent a standardized ocular examination and IOP measurement by GAT and ORA. Corneal hysteresis and corneal-compensated IOP were compared between groups.

The authors found that corneal hysteresis was lower in eyes with PACG (9.1 mm Hg; 95% confidence interval [CI], 8.7 to 9.4mmHg) and POAG (9.5mmHg; 95% CI, 9.2 to 9.5 mm Hg) compared with control eyes (10.4 mmHg; 95% CI, 10.1 to 10.6 mmHg; P < 0.001 for both). However, there was no difference (P = 0.16) in CH between PACG and POAG eyes. After adjusting for age, sex and IOP measurement by GAT, CH remained significantly lower only in eyes with PACG compared with control eyes (9.4 vs. 10.1 mmHg; P =0.006). Eyes with POAG had lower CH than control eyes but the difference was not statistically significant (9.6 vs. 10.1 mmHg; P = 0.06).