Correlation between central corneal thickness and visual field defects, cup to disc ratio and retinal nerve fiber layer thickness in primary open angle glaucoma patients

OBJECTIVE To assess the correlation between central corneal thickness (CCT) and visual field parameters, cup-to-disc ratio and retinal nerve fiber layer (RNFL) thickness in primary open-angle glaucoma (POAG) patients in Songklanagarind Hospital. MATERIAL AND METHOD A Retrospective analytical study of the medical records of primary open-angle glaucoma patients, between January 2006 and April 2008, were reviewed. All subjects underwent a complete eye examination. The CCT measurement was performed by ultrasonic pachymeter Mean deviation (MD), pattern standard deviation (PSD), cup-to-disc ratio, and the RNFL thickness of each patient were collected. The correlation coefficient between CCT and MD, PSD, cup-to-disc ratio and RNFL thickness was analyzed. RESULTS Twenty-six POAG patients (47 eyes) were eligible for the study. Mean age was 60.96 +/- 7.44 years. Average CCT was 511.15 +/- 29.66 microm. Mean AMD and PSD were--10.01 +/- 8.20 and 7.52 +/- 4.43 decibel respectively. Mean cup-to-disc ratio was 0.7 1+/- 0.17. Mean RNFL thickness of superior inferior temporal, nasal quadrants and all quadrants were 101.60 +/- 28.68, 87.15 +/- 32.56, 60.64 +/- 14.14, 61.83 +/- 13.96 and 77.80 +/-17.58 microm, respectively. There were significant correlations between CCT and MD (r = 0.532, p < 0.001), PSD (r = -0.288, p = 0.05), cup-to-disc ratio (r = -0.478, p = 0.001), and average RNFL thickness (r = 0.487, p = 0.001). CONCLUSION There were significant correlations between CCT and visual field parameters, cup-to-disc ratio, and RNFL thickness.