When treating patients with primary open-angle glaucoma (POAG), optometrists should be on the lookout for choroidal microvasculature dropout, as it may be a predictor of a faster rate of progressive retinal nerve fiber layer (RNFL) thinning, researchers from Korea report. Their study, published in Ophthalmology Glaucoma, also found the location of microvascular dropout was topographically linked with the location of the faster RNFL thinning.

The investigation enrolled 101 eyes of 101 POAG patients who underwent OCT angiography (OCT-A) imaging of the optic nerve head. At about two years, the participants’ RNFL thickness was measured again by spectral-domain OCT.   

The researchers evaluated the peripapillary microvasculature through en-face OCT-A imaging. The study defined choroidal microvasculature dropout as a focal sectoral capillary dropout with no visible microvascular network in the choroidal layer.

The study found microvasculature dropout in 47.5% of eyes, and RNFL thinning was much faster in eyes with microvasculature dropout—about -1.6μm/year compared with approximately -1.2μm/year in POAG-only eyes. In addition, 41 eyes with microvasculature dropout in the inferior hemisphere showed a faster rate of inferior RNFL thinning compared with eyes without microvasculature dropout.

Five eyes with microvasculature dropout in both the superior and inferior hemispheres showed faster rates of superior and inferior RNFL thinning compared with eyes without microvasculature dropout. The study also reported microvasculature dropout at baseline and the presence of disc hemorrhage during follow-up were independently associated with a faster rate of global RNFL thinning.