Purpose: The purpose of this article was to compare the frequencies of the parapapillary deep-layer microvasculature dropout (MvD) detected by optical coherence tomography angiography in eyes with primary open-angle glaucoma (POAG) and healthy eyes and to determine the topographic correlation between the MvD and the glaucomatous retinal nerve fiber layer (RNFL) defect in POAG eyes.
Methods: Microvasculature in the peripapillary deep-layer was evaluated in 150 POAG patients and 45 healthy controls using swept-source optical coherence tomography angiography to identify an MvD. Frequencies of MvDs were compared between the POAG and control groups. In POAG eyes with MvD, topographic correlation was assessed between the MvD and the RNFL defect defined based on the optical coherence tomography circumpapillary RNFL thickness measurement.
Results: MvD was observed as a sectoral filling defect in the parapapillary deep-layer in 53.9% (n = 62) of the POAG eyes, whereas none of the control eyes exhibited an MvD. POAG eyes with MvD had a thinner global RNFL (P < 0.001) and worse visual field mean deviation (P = 0.042) and were more myopic (P = 0.029), with axial length being longer (P = 0.046) than those without MvD. There was a good agreement between the circumferential extent and location of MvD and those of RNFL defect (95% limits of agreement of the difference ranged from -23.4 to 21.9° and -16.2 to 17.0°, respectively).
Conclusions: MvD was identified in the parapapillary deep layer exclusively in POAG eyes at the location of glaucomatous damage using optical coherence tomography angiography. The finding suggests that peripapillary deep-layer circulation is directly related to the glaucomatous optic neuropathy.