Lack of Correlation Between Diabetic Macular Edema and Thickness of the Peripapillary Retinal Nerve Fibre Layer

INTRODUCTION: We compared the thickness of the peripapillary retinal nerve fiber layer (RNFL) in patients with diabetic macular edema (DME) and/against the thickness in the normal population. METHODS: This cross-sectional study compared the RNFL thickness in patients with DME (DME group) using optical coherence tomography (OCT) to a comparable group of healthy (nondiabetic) patients (control group). Measurements were performed in different/the four peripapillary quadrants and in the macula region for the fovea, parafoveal, and perifoveal areas. The mean RNFL thickness was compared between both groups. RESULTS: There were fifty eyes of fifty nonglaucomatous diabetic patients with DME (29 with nonproliferative diabetic retinopathy [PDR] and 21 with PDR), and fifty eyes in the control group. The macular regions were significantly thicker in the DME group compared to the control group. The central foveal thickness was 149 μ thicker in eyes with DME compared to the control group (P < 0.001). The difference in total RNFL thickness between groups was not significant (4.4 μ [95% confidence interval: −3.1 to +12]). The between-group differences in peripapillary RNFL thickness by age group, glycemic control, history of intravitreal treatments, and refractive errors were not statistically significant (P > 0.05, all comparisons). CONCLUSION: Peripapillary RNFL thickness measurements were not significantly influenced by DME. Hence, OCT parameters could be used to monitor/early detect glaucomatous eyes even in the presence of DME.