Abstract
Purpose:
To investigate the relationship between corneal biomechanical properties and optic disc morphology in newly diagnosed and previously untreated normal-tension glaucoma patients.
Methods:
Ocular response analyzer was performed to obtain corneal hysteresis, corneal resistant factor, Goldmann-correlated intraocular pressure (IOP), and corneal-compensated IOP in NTG patients and normal controls. Optic disc morphology was imaged with Heidelberg retina tomography (HRT). All subjects underwent complete ophthalmologic examinations, including slit lamp examination, gonioscopy, fundoscopy, Goldmann applanation tonometry (GAT), best-corrected visual acuity, axial length, and central corneal thickness (CCT). Multiple linear regression analysis was used to investigate the associations of corneal biomechanical properties with HRT parameters, adjusted for disc area, GAT, CCT, age, axial length and spherical equivalent.
Results:
This study enrolled 95 eyes of 95 patients with previously untreated NTG, and 93 eyes of 93 age-matched normal subjects. Corneal hysteresis and corneal resistant factor were significantly lower in NTG group than in normal subjects (P = 0.004, P = 0.005, respectively). Rim area, rim volume, linear cup to disc ratio and mean retinal nerve fiber layer (RNFL) thickness were significantly worse in NTG group than in normal subjects (P < 0.001, P < 0.001, P < 0.001, and P = 0.001, respectively).<br /> Corneal hysteresis was directly associated with rim area, rim volume and mean RNFL thickness (P=0.012, P=0.028 and P=0.043, respectively) and inversely associated with linear cup to disc ratio (P=0.015) in patients with NTG, after adjustment for disc area, GAT, CCT, age, axial length and spherical equivalent. However, there was no significant association of corneal biomechanical properties and HRT parameters in normal controls.
Conclusions:
We found that lower CH is associated with smaller rim area and volume, thinner RNFL thickness and larger linear cup to disc ratio in newly diagnosed and previously untreated NTG patients independent of disc size, CCT, IOP and age. The results of this study highlight the importance of corneal biomechanical properties on change of optic nerve head in NTG, and may improve understandings on pathophysiological mechanism of glaucoma development.