Purpose To investigate the topographic relationship between parapapillary deep-layer microvasculature dropout (MvD) as assessed by optical coherence tomography (OCT) angiography (OCTA) and the juxtapapillary choroidal thickness (JPCT) in primary open-angle glaucoma (POAG).

Methods A total of 194 eyes (138 POAG and 56 control eyes) having parapapillary atrophy (PPA) were imaged using the swept-source OCT and OCTA to examine the microstructure of PPA and measure the JPCT, and to determine the presence of the MvD. MvD was defined as a focal sectoral capillary dropout without any visible microvascular network identified in the parapapillary deep-layer in the en face OCTA images.

Results JPCT was smaller in the POAG group than control group at 6-, 6.5-, 7- and 7.5-o’clock meridians (all p≤0.002). When POAG eyes were classified into those with parapapillary γ-zone and those with only β-zone without γ-zone, the mean JPCT was significantly smaller in the latter (p=0.027). The JPCT differed between with and without MvD only in eyes with a γ-zone: the JPCT was smaller in the eyes having MvD at 7- and 7.5-o’clock meridians (both p=0.001), where MvD was detected most frequently. However, such a difference was not observed in the eyes with only β-zone without the γ-zone at any of the meridians.

Conclusions Localised reductions in JPCT were observed at the location of MvD in POAG eyes with parapapillary γ-zone. Such a correlation was not observed in the POAG eyes with only β-zone, but the mean JPCT was significantly smaller in this group.