OCT Optic Nerve Head Morphology in Myopia II: Peri-Neural Canal Scleral Bowing and Choroidal Thickness in High Myopia An American Ophthalmological Society Thesis

& BULL; PURPOSE: To use optical coherence tomography (OCT) to characterize optic nerve head (ONH) peri-neural canal (pNC) scleral bowing (pNC-SB) and pNC choroidal thickness (pNC-CT) in 69 highly myopic and 138 healthy, age-matched, control eyes.& BULL; DESIGN: Cross-sectional, case control study.& BULL; METHODS: Within ONH radial B-scans, Bruch mem-brane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and pNC scleral surface were seg-mented. BMO and ASCO planes and centroids were de-termined. pNC-SB was characterized within 30 & DEG; foveal-BMO (FoBMO) sectors by 2 parameters: pNC-SB-scleral slope (pNC-SB-SS), measured within 3 pNC segments (0-300, 300-700, and 700-1000 & mu;m from the ASCO centroid); and pNC-SB-ASCO depth relative to a pNC scleral reference plane (pNC-SB-ASCOD). pNC-CT was calculated as the minimum distance between the scle-ral surface and BM at 3 pNC locations (300, 700, and 1100 & mu;m from the ASCO).& BULL; RESULTS: pNC-SB increased and pNC-CT decreased with axial length ( P < .0133; P < .0001) and age ( P < .0211; P < .0004) among all study eyes. pNC-SB was increased ( P < .001) and pNC-CT was decreased ( P < .0279) in the highly myopic compared to control eyes, and these differences were greatest in the inferior quadrant sectors ( P < .0002). Sectoral pNC-SB was not related to sectoral pNC-CT in control eyes, but was in -versely related to sectoral pNC-CT ( P < .0001) in the highly myopic eyes.& BULL; CONCLUSIONS: Our data suggest that pNC-SB is in-creased and pNC-CT is decreased in highly myopic eyes and that these phenomena are greatest in the inferior sec-tors. They support the hypothesis that sectors of maxi-mum pNC-SB may predict sectors of greatest susceptibil-ity to aging and glaucoma in future longitudinal studies of highly myopic eyes.