Optic Disc Vascular Density in Normal-Tension Glaucoma Eyes with or without Branch Retinal Vessel Occlusion
Abstract We analyzed the vascular densities (VDs) of the optic disc areas in eyes with normal-tension glaucoma (NTG) according to branch retinal vessel occlusion (BRVO) status. The VDs of the optic discs and peripapillary areas of 68 patients with NTG + BRVO (eyes with BRVO and fellow eyes with NTG alone) and 37 patients with NTG alone (controls) were measured on binarized angiographic images obtained via swept-source optical coherence tomography angiography. Disc VDs were subdivided into large vessel and small vessel VDs. VD measurements were compared among groups and correlations were assessed. The small vessel and large vessel VDs of the optic disc and peripapillary area differed significantly among eyes in the control, NTG alone, and NTG + BRVO groups (all P < 0.001). More optic disc VDs were significantly larger and fewer were significantly smaller in eyes with BRVO, compared to fellow eyes and control eyes. Large optic disc VD was negatively correlated with small optic disc VD (r = -0.697, P < 0.001). Peripapillary VD was lower in eyes with BRVO than in control eyes, but not in fellow eyes (P < 0.001 and P = 0.975, respectively). In conclusion, significant disc and peripapillary VD changes were observed in eyes with BRVO. However, larger optic disc VD and smaller VD were observed in fellow eyes with NTG alone, but not in control eyes, suggesting that larger optic disc VD may contribute to NTG development in patients with BRVO.