Parapapillary deep-layer microvasculature dropout is only found near the retinal nerve fibre layer defect location in open-angle glaucoma

We aimed to investigate the topographic correspondence between deep-layer microvasculature dropout (MvD) and retinal nerve fibre layer (RNFL) defects in eyes with open-angle glaucoma (OAG) using spectral-domain optical coherence tomography (SD-OCT) and optical coherence tomography angiography (OCT-A).

Microvasculature dropout width and location were determined using OCT-A, RNFL thickness, RNFL defect width and location were revealed using SD-OCT. The association between MvD and RNFL widths and that between the location of the MvD and RNFL defects were investigated. In addition, patients with OAG were divided into two groups: the RNFL defect in one hemiretina (RNFLD-HR) group (n = 24 eyes) and the RNFL defects in both hemiretinas (RNFLD-BR) group (n = 25 eyes). The presence, width and location of MvDs were compared between the two groups.

Forty-nine eyes were included. In 24 RNFLD-HR eyes, all MvDs were found in the inferior area, corresponding with the location of the RNFL defect. Meanwhile, in 25 RNFLD-BR eyes, 18 MvDs (72%) were found in the inferior hemiretina, two (8%) were found in the superior hemiretina, and five (20%) were found in both hemiretinas. In RNFLD-BR eyes, the average RNFL thickness was thinner in a location with MvD than a location without MvD.

Considering that MvD is only observed at the location of the RNFL defect in RNFLD-HR eyes and is usually found in the location of more severe RNFL defects in RNFLD-BR eyes, MvD seems to be a sign that accompanies glaucomatous damage in OAG eyes.