Microstructure of Nonjuxtapapillary Microvasculature Dropout in Healthy Myopic Eyes.

Purpose: The purpose of this study was to characterize the microstructure of the nonjuxtapapillary microvasculature dropout (MvD) in healthy myopic eyes. Methods: This cross-sectional study included 50 eyes (25 eyes with a nonjuxtapapillary MvD and 25 age-matched eyes without any MvD) from a cohort of 126 nonglaucomatous healthy myopic eyes having parapapillary atrophy (PPA) γ-zone. The parapapillary deep-layer microvasculature was evaluated in en-face images obtained using swept-source optical coherence tomography (OCT) angiography (OCTA). A nonjuxtapapillary MvD was defined as an area with focal absence of vascular signals in the distal portion of PPA confined to the nonjuxtapapillary area. Enhanced depth-imaging OCT scanning was performed to assess the parapapillary microstructure. Results: Nonjuxtapapillary MvD was found in 25 eyes (19.8%). The parapapillary microstructure at the nonjuxtapapillary MvD in 18 eyes was characterized by the misalignment of Bruch's membrane (BM)-retinal pigment epithelium (RPE) complex, which was identified by the absence of BM-RPE complex and the presence of the inner retina and sclera. In seven eyes with a nonjuxtapapillary MvD but without such misaligned BM-RPE complex, RPE atrophy was observed at the location of the nonjuxtapapillary MvD. Eyes with a nonjuxtapapillary MvD had a longer axial length (AXL; P = 0.013) and a wider γ-zone (P < 0.001) than age-matched control eyes without any MvD. Conclusions: The microstructure at the nonjuxtapapillary MvD in healthy myopic eyes was characterized in approximately 70% of eyes by temporally misaligned BM-RPE complex. Although the clinical importance of the nonjuxtapapillary MvD remains to be determined, it should be differentiated from the parapapillary choroidal MvD observed in glaucoma.