Parapapillary Choroidal Microvasculature Dropout in Glaucoma: A Comparison between Optical Coherence Tomography Angiography and Indocyanine Green Angiography.

PURPOSE: To investigate whether the parapapillary choroidal microvasculature dropout (MvD) determined by optical coherence tomography angiography (OCTA) in glaucomatous eyes indicates a true perfusion defect and whether the MvD accurately represents the area of nonperfusion.

DESIGN: Observational case series.

PARTICIPANTS: Thirty primary open-angle glaucoma (POAG) patients with choroidal MvD as determined by OCTA and 13 POAG patients without this dropout.

METHODS: Peripapillary circulation was evaluated using both OCTA and indocyanine green angiography (ICGA). For OCTA, the choroidal microvasculature was evaluated using 4.5×4.5-mm choroid-disc vessel density maps of OCTA images of the optic nerve head. An MvD was identified in OCTA by the presence of a capillary dropout. A filling defect observed in ICGA was defined as a perfusion defect (ICG PD).

MAIN OUTCOME MEASURES: The topographic correlations between MvD and ICG PD determined based on their circumferential extent, location, and area.

RESULTS: The ICG PD was observed as a sectoral filling defect in the 30 POAG patients exhibiting MvD and appeared identical to the MvD in terms of the shape and location. The circumferential extent, location, and area of ICG PD did not differ from those of the MvD (all P > 0.05). The ICG PD was not found in any of the eyes not having the MvD.

CONCLUSIONS: A localized MvD observed in the parapapillary choroid using OCTA coincided with the ICG PD detected by ICGA. These findings indicate that OCTA accurately images impaired parapapillary choroidal circulation.