Evaluation of peripapillary retinal nerve fiber layer thickness in patients with primary open-angle glaucoma

Abstract

Introduction/Objective. The objective of the study was to determine the difference in peripapillary retinal nerve fiber layer (RNFL) thickness in patients with open-angle glaucoma (POAG) in comparison to the healthy population and according to the progression of the disease. Methods. Four groups were formed among 120 patients: group without glaucoma, early, moderate POAG, and preperimetric glaucoma group. Visual field and optical coherent tomography were performed. Results. RNFL thickness value was found to be the highest in the inferior quadrant, the second highest in the superior one, the third highest in the nasal one, and the lowest value was found to be in the temporal quadrant. The highest average value of RNFL thickness was in the superior quadrant of the healthy group (124.3 ± 17.8 μm), and the lowest one was in the temporal quadrant of the moderate group (46.5 ± 10.8 μm). Other RNFL thickness values per quadrants among groups were distributed between these two endpoints. Mean value of peripapillary RNFL thickness (AvgThic) in patients with moderate POAG was lesser than in patients with early POAG, which, in turn, was lesser than that in the healthy subjects (59.6 ± 10.6 μm vs. 73.4 ± 12.1 μm vs. 105.5 ± 11.3 μm). AvgThic in the preperimetric glaucoma group was 83.6 ± 9.2 μm. Pearson correlation showed a high positive correlation between mean deviation values and the following parameters: AvgThic, S, I, Smax, Imax, Savg, Iavg. Receiver operating characteristic curves found that the parameter with the best diagnostic ability was AvgThic, with the area of 0.803 (< 0.0005), sensitivity of 67%, and specificity of 83.3%. Conclusion. Peripapillary RNFL thickness parameters AvgThic, S, I, Smax, Savg, Iavg, Imax have an excellent ability to discriminate between healthy eyes and eyes with POAG. The parameter with the highest specificity and sensitivity is AvgThic, which makes it the best for early detection and monitoring of POAG.

Keywords

• retinal nerve fiber layer
• primary open-angle glaucoma
• optical coherent tomography
• avgthic