Low-tension glaucoma—poorly understood and infrequently studied—may be a distinct condition with telltale predictors, including a reduction of the superficial macular, peripapillary, optic nerve and choriocapillaris compared with healthy eyes, a study in the Journal of Glaucoma reports.

In this cross-sectional investigation, researchers prospectively acquired images from 49 eyes with low-tension glaucoma and 40 healthy eyes using optical coherence tomography angiography (OCT-A). Investigators analyzed perfusion density and vessel length density within a 5mm diameter circle centered over the macula and optic nerve head. 

They found the low-tension glaucoma group had a statistically significant reduction in perfusion density of the choriocapillaris compared with normal controls (71.74 ± 8.37% vs. 80.48 ± 3.84%). The study also reported no statistically significant difference in perfusion density between the low-tension glaucoma and control groups for the superficial vascular plexus, deep capillary plexus or the optic nerve head and peripapillary area. Also of note: the low-tension glaucoma group showed statistically significant reductions in vessel length density compared with normal controls for the superficial vascular plexus and optic nerve head and peripapillary area, whereas the deep capillary plexus vessel density was similar between the two groups.

On OCT-A, eyes with low-tension glaucoma appear to show a lower choriocapillaris perfusion density, as well as a lower superficial vascular plexus and optic nerve head and peripapillary vessel length density compared with normal eyes, investigators said.

“Low tension glaucoma patients represent an interesting and possibly distinct group for whom the retinal microvasculature may be particularly relevant to disease pathophysiology,” researchers noted in their paper. 

This study is novel, since there are few investigations to date that compare vascular densities of both the macula and optic nerve head region in low-tension glaucoma and normal controls using OCT-A, investigators said. Additionally, this research marks the first attempt to compare these cohorts using vessel length density. However, since low-tension glaucoma patients were compared with normal eyes in the control group, one possible limitation of this study was not including a high intraocular pressure, primary open-angle group, they added.