Macular Ganglion Cell-Inner Plexiform Layer and Retinal Nerve Fiber Layer Thickness in Eyes With Primary Open-Angle Glaucoma Compared With Healthy Saudi Eyes: A Cross-Sectional Study.

Abstract

We compared the thickness of the ganglion cell-inner plexiform layer at the macula (mGCIPL) and the thickness of the retinal nerve fiber layer (RNFL) in different regions of the retina in eyes with primary open-angle glaucoma (POAG group) and normal eyes (control group). This was a cross-sectional study performed in 2014. Spectral domain optical coherence tomography (SD-OCT) was used to measure mGCIPL and RNFL thickness. Age-adjusted means and standard deviation were calculated. Age, sex, refractive status, corneal thickness, and stage/severity of glaucoma (defined by vertical cup-to-disc ratio and visual field changes) were associated to outcomes. Statistical significance was indicated by P < 0.05. There were 50 eyes in the POAG group and 52 eyes in the control group. The difference in age between patients in both groups was statistically significant (P < 0.001). The age-adjusted measurements were thinner for POAG with a mean difference (DF) of 11.1 μm for mGCIPL and 8 μm for mRNFL. The mGCIPL to mRFNL ratio was 2.1 in the POAG group and 1.9 in the control group (degrees of freedom = 0.2, P = 0.001). The mGCIPL and RNFL thickness decreased as the severity of glaucoma increased. The mGCIPL to mRNFL ratio was a predictor of the severity of field defects in POAG (AUROC = 0.66, P = 0.0002). Age and myopia were confounders to the association of OCT findings and the visual field changes in POAG (P = 0.07). There was generalized thinning of retinal layers in eyes of nondiabetic Arab patients with POAG. OCT parameters can be important for detecting and monitoring glaucoma cases.