Abstract
PurposeTo 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.MethodsOne 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.ResultsForty-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).ConclusionsOCTA-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.
Highlights
Ocular blood flow is thought to have an important role in the pathology of glaucoma.[1,2,3] In particular, vascular dysfunction in the optic nerve head (ONH) has been proposed as a contributing factor to the development and progression of glaucoma.[3]
Forty-two, 37, and 44 eyes were identified as having microvasculature dropout (Mvd) within the optic disc (Mvd-D), pseudo-Mvd-D, and no Mvd-D, respectively
optical coherence tomography angiography (OCTA)-derived Mvd-D was strongly associated with the presences of microvasculature dropout in the parapapillary region (Mvd-P) and focal lamina cribrosa defects, and these 3 findings were topographically associated with each other
Summary
Ocular blood flow is thought to have an important role in the pathology of glaucoma.[1,2,3] In particular, vascular dysfunction in the optic nerve head (ONH) has been proposed as a contributing factor to the development and progression of glaucoma.[3]. In addition to being non-invasive, the actual measurements are performed relatively quickly.[9,10,11,12] Peripapillary vessel density using OCTA has been shown to be reduced in glaucoma eyes and has been proposed as a diagnostic tool for glaucoma.[13,14] Further, it recently has been reported that dropout of the deep-layer microvasculature within areas of parapapillary atrophy is associated with systemic and ocular factors including focal lamina cribrosa (LC) defects in primary open-angle glaucoma (POAG) patients.[15] Formation of a focal LC defect is thought to be derived from structural changes at and around the LC and might be the cause of mechanical rupture of small blood vessels.[16,17,18,19,20,21,22,23] It was suggested that the significant association between microvasculature dropout (Mvd) in the parapapillary deep-layer (Mvd-P) and focal LC defects is caused by disruption of the laminar beams during the development of focal LC defects because both microvasculature in the parapapillary region and LC are downstream from the short posterior ciliary artery.[23] Considering these anatomic relationships, it is not surprising that focal LC defects affect microvasculature structures in the parapapillary area, as well as within the optic disc. There is little information regarding the relationship among Mvd within the optic disc (Mvd-D), Mvd-P, and focal LC defects
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