Comparing optical coherence tomography angiography biomarker for primary open-angle glaucoma and normal tension glaucoma progression in different stage

Abstract: PURPOSE: To compare peripapillary and parafoveal microvasculature between primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) at different disease stages using optical coherence tomography angiography (OCTA). MATERIALS AND METHODS: This retrospective study classified eyes into early, moderate, or severe visual field defect based on Hodapp-Parrish-Anderson criteria. OCTA was used to assess radial peripapillary capillaries (RPCs), retinal nerve fiber layer (RNFL), parafoveal vessel density, and ganglion cell complex thickness. Global and sectoral parameters were compared between POAG and NTG, with subgroup analysis by disease severity. RESULTS: In early-stage glaucoma, global RNFL thickness was significantly lower in NTG eyes (87.5 ± 11.3 µm) compared to POAG eyes (92.4 ± 10.5 µm, P = 0.034), especially in the superior-nasal sector (111.7 ± 28.4 µm vs. 122.7 ± 26.8 µm, P = 0.030). In severe-stage glaucoma, POAG eyes showed lower nasal-superior RPCs (32.1% ± 9.8% vs. 39.2% ± 8.8%, P = 0.044), nasal-inferior RPCs (32.9% ± 10.6% vs. 40.0 ± 6.9%, P = 0.012), and temporal-superior RNFL thickness (53.0 ± 15.0 µm vs. 69.9 ± 21.7 µm, P = 0.019). CONCLUSION: The microvasculature in the sectoral peripapillary and parafoveal regions shows significant differences between POAG and NTG across various stages. This suggests that the mechanisms underlying these glaucoma subtypes may differ at different stage.