Correlation between Retinal Nerve Fiber Layer Thickness and Cup-to- Disc Ratio in Glaucoma Suspects Using Optical Coherence Tomography at University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State, Nigeria

Abstract

Aim: To determine the correlation between retinal nerve fiber layer thickness and vertical cup disc ratio in glaucoma suspects in the University of Port Harcourt teaching hospital, Port Harcourt, Nigeria. Study Design: Hospital-based observational study conducted between October 2nd, 2012 and January 31st2013. Methodology: Participants were selected using consecutive allocation of glaucoma suspects as they presented to the glaucoma clinic. Observations were done using the Optical Coherence Tomography machine. Data was analyzed using the statistical package EPI info version 6.04d. Results: One hundred and twenty participants (n =120) comprising 60 males (50%) and 60 females (50%) with a mean age of 42.8±13.79 were examined; The age range was 19 to 75 years. The average retinal nerve fiber layer was 132.254 µm in the inferior quadrant, 127.504 µm in the superior quadrant, 80.533 µm in nasal quadrant and 61.500 µm in temporal quadrant. Vertical cup disc ratio increased with decreasing RNFL thickness (p<0.05; r = - 0.21). Disc size was noticed to increase with increasing VCDR (p= 0.001). Conclusion: There was no strong correlation between vertical cup disc ratio and retinal nerve fiber layer thickness among the glaucoma suspects. There was a weak positive correlation between the optic disc diameter and the retinal nerve fiber layer thickness of the subjects.