Abstract
Purpose: :
To investigate corneal biomechanical properties in patients with exfoliation syndrome (XFS) and exfoliative glaucoma (XFG).
Methods: :
We prospectively enrolled XFS patients and normal controls, and XFG patients and normal-tension glaucoma (NTG) patients as controls. Data collected included age, intraocular pressure (IOP), visual field (VF) mean deviation (MD) and central corneal thickness (CCT - ultrasound pachymetry). After a complete ophthalmic examination, all patients underwent corneal hysteresis (CH) and corneal resistance factor (CRF) measurements using the Ocular Response Analyzer (the mean of 3 measurements was considered). Whenever both eyes were eligible, one was randomly selected. We compared corneal biomechanical parameters between XFS/XFG patients and controls using analysis of covariance (accounting for any possible difference in age, IOP, CCT and MD between patients).
Results: :
A total of 23 XFS patients (mean age, 71.1±8.9 years) and 23 controls (mean age, 67.7±3.8 years), and 33 XFG (mean age, 74.5±9.5 years) and 33 NTG patients (mean age, 65.1±11.2 years) were included. Significantly higher CRF values were found in XFG eyes (9.1±1.9 mmHg) compared to NTG eyes (8±1.5mmHg; p<0.01). No significant difference was found considering CH values (8.4±1.6 mmHg vs 7.9±1.9 mmHg; p=0.24). There were no significant differences in CRF or CH values between XFS patients (CRF=10.1±1.5; CH= 9.2±2.5 mmHg) and controls (CRF=10±1.4; CH=9.9±1.4 mmHg; p>0.20). When compared to controls without glaucoma, both glaucoma groups (XFG and NTG) had significantly lower CH and CRF values (p<0.01). Finally, both CH and CRF were significantly associated with the disease stage (as expressed by VF MD); eyes with worse MD had lower CH and CRF values (R2>0.12, p<0.01).
Conclusions: :
The presence of XFS does not seem to affect corneal biomechanics as measured by the ORA. Both high-tension (XFG) and normal-tension glaucoma eyes have lower values of corneal biomechanical parameters than controls, and lower CRF values are found in those with NTG. Finally, corneal biomechanics seems to be associated with the degree of functional damage in these eyes.
Keywords: intraocular pressure • anterior segment