Association of Deep Optic Nerve Head Structural Remodeling with Choroidal Microvasculature Dropout in Glaucoma with and without Myopia

Abstract

Purpose: To evaluate associations between parapapillary choriocapillaris microvascular dropout (MvD) and optical coherence tomography (OCT)-detected deep optic nerve head (ONH) structures in glaucomatous eyes with and without myopia. Design: Cross-sectional study from clinical trial data. Methods: 394 eyes from 262 patients with primary open-angle glaucoma (POAG) and glaucoma suspects were stratified into three groups of no myopia (axial length (AL)<24 mm; n = 144), mild myopia (24 mm ≤ AL < 26 mm; n = 174), and high myopia (AL ≥ 26 mm; n = 76). Spectralis ONH OCT radial B-scans were acquired relative to the Foveal–Bruch's Membrane Opening (FoBMO) axis. Bruch's Membrane Opening (BMO) and anterior scleral canal opening (ASCO) were manually segmented, and their size and shape were calculated. BMO/ASCO offset magnitude, neural canal obliqueness, and neural canal minimum cross-sectional area (NCMCA) were measured. The presence, area, and angular circumference of juxtapapillary MvD were evaluated using OCT-angiography en face choroidal images and B-scans. Results: The MvD area (95% CI) was significantly greater in highly myopic eyes (0.38 [0.30, 0.47] mm²), compared with mild myopia (0.33 [0.27, 0.39] mm²) and no myopia (0.21 [0.14, 0.27] mm²) (P = .002). The MvD angular circumference was also significantly larger in mild myopia (75.4 [64.0, 86.9]°), followed by high myopia (74.5 [58.0, 90.9]°) and no myopia (52.6[39.9, 65.3]°) (P = .017). The highly myopic group showed a significantly larger BMO area, NCMCA ovality index, BMO/ASCO offset magnitude, and neural canal obliqueness, along with smaller NCMCA, compared to the other groups (all P < .01). In multivariable analysis, NCMCA, NCMCA ovality index, BMO/ASCO offset magnitude, and neural canal obliqueness were significantly associated with both MvD presence (all P < .05) and MvD area (all P < .05). Additionally, NCMCA ovality index and neural canal obliqueness were associated with MvD angular circumference (P = .01 and P = .004, respectively). Conclusions: In myopic POAG eyes, the presence and area of MvD were associated with NCMCA, NCMCA ovality index, BMO/ASCO offset magnitude, and neural canal obliqueness, whereas MvD angular circumference was associated only with NCMCA ovality index and neural canal obliqueness. Evaluating choriocapillaris MvD alongside deep ONH structural alterations may provide clinical insights into the pathogenesis of glaucoma in myopia.