The Inter-Eye Differences of the Circumpapillary Microvasculature in Primary Open-Angle Glaucoma.

Purpose: To assess inter-eye differences of circumpapillary vessel density (cpVD) in patients with primary open-angle glaucoma (POAG) and elucidate factors implicated in glaucomatous vascular pathology. Methods: POAG subjects and controls underwent optical coherence tomography (OCT) and OCT angiography (OCTA) imaging in both eyes. Inter-eye differences of OCT, OCTA, visual field (VF) and other ophthalmic parameters were assessed. Results: Seventy-two POAG subjects and 53 controls were similar in age, gender, and visual acuity (P ≥ 0.28 for all). POAG subjects had greater retinal nerve fiber layer (RNFL) asymmetry than controls (10 ± 10 µm vs. 5 ± 5 µm, P < 0.001). POAG patients also demonstrated significantly asymmetric mean deviation (MD) between the worse (-5.2 ± 4.0 dB) and better eye (-1.5 ± 2.6 dB, P < 0.001). However, POAG subjects had similar inter-eye cpVD asymmetry compared to controls (3.5% ± 2.6% vs. 3.1% ± 1.9%, respectively; P = 0.32). In a multivariable regression, MD asymmetry was associated with greater RNFL asymmetry (β = 0.540; 95% confidence interval [CI], 0.249-0.830; P < 0.001), whereas treated systemic hypertension (β = -0.415; 95% CI, -0.679 to -0.151; P < 0.001) was associated with decreased cpVD asymmetry in POAG subjects. Conclusions: POAG subjects demonstrated greater inter-eye RNFL asymmetry than controls, but similar cpVD asymmetry. Although RNFL asymmetry was associated with difference in VF, inter-eye difference of circumpapillary microvasculature was minimized by systemic hypertension treatment, supporting systemic determinants of glaucomatous vascular pathology. Translational Relevance: Our findings highlight a discordance in vascular pathology and structural RNFL damage between eyes in POAG, suggesting a systemic predisposition of vascular pathology in POAG.