For patients with primary open-angle glaucoma (POAG), focal capillary density may be tied to a wider range of VF loss and a larger proportion of the VF compared with retinal nerve fiber layer (RNFL) thickness, new research published in Investigative Ophthalmology & Visual Science suggests.

The study included 119 eyes of 86 POAG participants who underwent standard automated perimetry, OCT-based nerve fiber thickness measurements and OCT-A imaging.

The subjects’ VF mean deviation was significantly associated with global capillary perfusion density (β=0.13±0.08) and global RNFL thickness (β=0.09±0.02).

The researchers noted a strong linke between focal capillary density and VF loss in about 67% of 24-2 VFs encompassing 34 test locations, with 24 sites within 20° of retinal eccentricity.

In comparison, focal nerve layer thickness was associated with just 16 VF test locations, or roughly 31% of 24-2 VFs, with eight locations within 20° of eccentricity.

For test locations in the central 10° VF, losses below the breakpoint were tied to focal capillary density (slope: 0.89±0.12) but not to focal nerve layer thickness (slope: 0.57±0.39).

The researchers said their focal approach allowed them to use the actual VF losses at the test locations without averaging over a larger sector, which enabled a more accurate representation of focal changes in the VF, nerve fiber layer thickness and capillary density that could otherwise be unclear in a global or sectional analysis.

“The findings suggest that capillary density may be useful for modeling focal VF losses in glaucoma. Further studies with longitudinal data are necessary to evaluate the applicability of these findings to glaucoma progression,” the study authors wrote in their paper.

Wong D, Chua J, Lin E, et al. Focal structure-function relationships in primary open-angle glaucoma using OCT and OCT-A measurements. Invest Ophthal Vis Sci. 2020;61(14):33.