Abstract
Purpose: :
To investigate the association between corneal biomechanical parameters, as measured by the Ocular Response Analyzer (ORA), and retinal nerve fiber layer (RNFL) thickness measurements.
Methods: :
Patients with established or suspect glaucoma ||were recruited from the longitudinal Diagnostic Innovations in Glaucoma Study (DIGS) and from the African Descent and Glaucoma Evaluation Study (ADAGES) at the University of California, San Diego. Goldmann applanation intraocular pressure (IOP), axial length, central corneal thickness (CCT), and ORA measurements [corneal compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal resistance factor (CRF), and corneal hysteresis (CH)] were obtained for all participants. RNFL thickness measurements were obtained using GDx-ECC (Carl-Zeiss Meditec) and Spectralis-OCT (SDOCT, Heidelberg Engineering). The association of ORA parameters and RNFL thickness measurements was evaluated by univariable and multivariable mixed models.
Results: :
There were 248 eyes in the SDOCT group and 207 eyes in the GDx-ECC group. There was a significant, although weak, association between CH and RNFL average thickness in both groups (R2 = 0.02; P = 0.02 [SDOCT] and R2 = 0.06; P < 0.001 [GDx-ECC]). For the CRF, corresponding values were R2= 0.02 (P=0.01) for SDOCT and R2=0.04 (P = 0.01) for GDx-ECC. In multivariable mixed models adjusting for corneal thickness measurements (CCT), age, axial length, and ancestry, the relationship between CRF and RNFL thickness remained statistically significant on SDOCT measurements (R2 = 0.1; P = 0.03) but not on GDx-ECC (R2 = 0.18; P = 0.9). The association between CH and average RNFL thickness became not significant (R2 = 0.10; P = 0.05 [SDOCT] and (R2 = 0.18; P = 0.23 [GDx-ECC]).
Conclusions: :
Lower corneal hysteresis and corneal resistance factor were associated with thinner RNFL thickness. This association, however, was not observed after adjustment for corneal thickness measurements, axial length, age, sex, and ancestry.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00221897