Effects of glaucoma and central corneal thickness on optic nerve head biomechanics

Purpose To evaluate effects of glaucoma and central corneal thickness (CCT) on optic nerve head biomechanics. Methods Four groups were formed according to CCT measurements and the presence of glaucoma. Glaucomatous patients with thin ( 570 µ) corneas composed groups 1 and 3, respectively. Nonglaucomatous patients with thin and thick corneas composed groups 2 and 4, respectively. Real-time elastography (RTE) was performed on all groups, and optic nerve strain rate (ONSR), orbital fat strain rate (OFSR), and strain ratio of orbital fat to the optic nerve and medial and lateral parts of the optic nerve (SROFON, SROFMON, SROFLON, respectively) were obtained and compared between groups. The correlations between CCT and these parameters were also investigated. Results Statistically significant difference was not found between groups in terms of strain rate of optic nerve and orbital fat, SRFON, SROFMON and SROFLON. There was a positive correlation between ONSR and OFSR and mean CCT in patients with CCT thinner than 510 µ ( p : 0.03 r : 0.26, p : 0.01 r : 0.32 respectively). Conclusion SROFON, SROFLON and SROFMON values did not differ between glaucomatous and nonglaucomatous patients with thin or thick CCTs. The correlations between CCT and OFSR and ONSR were found to be statistically significant in patients with thin CCT.