Microvasculature Dropout Location Affects Structural Progression in OAG

Microvasculature dropout within the inferior quadrant is associated with faster retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) thinning in the same quadrant when intraocular pressure (IOP) fluctuates long-term in individuals with open angle glaucoma, according to research published in Eye. However, these thickness changes are not associated with IOP fluctuations within the temporal quadrant, according to the report.

Researchers enrolled 181 consecutive participants with open angle glaucoma and peripapillary choroidal microvascular dropout in the retrospective review that included individuals treated at a single center between March 2017 and December 2020. The team stratified participants according to microvasculature dropout location (temporal: n=110; 39% men; age, 60.5±12.6 years; inferior: n =71; 39% men; age, 60.3±11.1 years) and obtained RNFL and GCIPL thicknesses from optical coherence tomography-angiography (OCT-A) data.

Eyes with microvasculature dropout in the inferior sector showed faster rates of thinning in the inferior RNFL compared with eyes with temporal dropout (−0.833 vs −0.144 µm/ year) when long-term IOP fluctuation was larger than the median value of 1.7 mm Hg (P = .022), the report shows. These long-term IOP fluctuations were associated with inferior RNFL thinning in eyes with inferior microvasculature dropout (P =.002), but not in eyes with temporal dropout.

“These findings suggest that progression of glaucoma in association with [microvasculature dropout] in different locations are affected by different risk factors,” according to the study authors. “[Microvasculature dropout] may be useful for detection of patients at a high risk of rapid progression who require close observation and strict IOP control.”

Study limitations include a retrospective design, small sample size, projection artifacts of superficial vessels that may have created false images of vascularity in the deep retinal
layers, and an ethnically homogenous study sample, which may limit the globalization of these findings.