Optic disc microvasculature dropout in primary open-angle glaucoma measured with optical coherence tomography angiography

PURPOSE: To evaluate microvasculature dropout in the optic disc (Mvd-D) using optical coherence tomography angiography (OCTA) and investigate factors associated with Mvd-D in primary open-angle glaucoma (POAG) eyes. METHODS: One hundred twenty-three eyes of 123 POAG patients were included from the Diagnostic Innovations in Glaucoma Study. The 3.0×3.0-mm optic nerve head OCTA scans were acquired using a spectral-domain OCT instrument. Images with whole-signal-mode were evaluated. Eyes were classified into 3 categories (Mvd-D, pseudo-Mvd-D, and no Mvd-D). Mvd-D and pseudo-Mvd-D had complete loss of OCTA signals on the temporal side of the optic disc on the en face projection image. They were distinguished base on the visualization of the anterior lamina cribrosa in the horizontal B-scans of that area. No Mvd-D was defined when no complete signal loss of OCTA signals was observed. Covariates including focal lamina cribrosa defects assessed by swept-source OCT and microvasculature dropout in the parapapillary region (Mvd-P) were analyzed. RESULTS: Forty-two, 37, and 44 eyes were identified as having Mvd-D, pseudo-Mvd-D, and no Mvd-D, respectively. The eyes with Mvd-D showed significantly lower intraocular pressure, worse visual field mean deviation, larger cup-to-disc ratio, thinner circumpapillary retinal nerve fiber layer (cpRNFL), and lower circumpapillary vessel density within the RNFL than the eyes with pseudo-Mvd-D or the eyes without Mvd-D. Multivariable logistic regression analysis showed significant associations of Mvd-D with larger cup-to-disc ratio (OR, 1.08; P = 0.001), worse visual field mean deviation (OR, 1.09; P = 0.048), higher prevalence of focal lamina cribrosa defect (OR, 9.05; P = 0.002), and higher prevalence of Mvd-P (OR, 10.33; P <0.001). CONCLUSIONS: OCTA-derived Mvd-D was strongly associated with the presences of Mvd-P and focal lamina cribrosa defects, and these 3 findings were topographically associated with each other.