Peripapillary Perfusion, Vessel Density Linked With Faster RNFL Loss in Glaucoma

Lower baseline peripapillary perfusion and vessel density are associated with a faster rate of retinal nerve fiber layer (RNFL) loss in patients with primary open-angle glaucoma (POAG), according to findings published in the American Journal of Ophthalmology.

Determining which glaucoma patients have a higher risk of disease progression aids in treatment planning. Several clinical and diagnostic markers have been linked with disease progression, including older age, higher mean intraocular pressure (IOP), greater fluctuation of IOP, thinner cornea, presence of disc hemorrhage, greater severity of disease at baseline, and decreased ocular perfusion.

One way to visualize the blood vessels of the eye is optical coherence tomography angiography (OCT-A). Optical microangiography (OMAG) is a commercially available algorithm to achieve blood vessel delineation on OCT-A images. OMAG uses both the intensity and phase information from B-scans repeated at the same position to delineate blood vessels. Previous studies found that OMAG can reveal reduced vessel density in the peripapillary and macular regions of eyes with glaucoma.

To evaluate the association between OMAG measurements and progressive RNFL loss in POAG, investigators studied 64 eyes of 40 POAG patients (108 quadrants) with mild to moderate functional damage. They found that the average mean deviation, RNFL and ganglion cell inner plexiform layer (GCIPL) thicknesses of the analyzed quadrants at baseline were -5.5±2.9 dB, 96.5±17.9 μm, and 73.8±8.6 μm, respectively. Peripapillary perfusion densities (PD) and vessel densities (VD) in the quadrant were 44.6±5.9% and 17.5±2.2 mm/mm², respectively. The rate of quadrant RNFL change was -1.8±0.6 μm per year. Multivariate mixed models showed that lower peripapillary PD (P =.01) and lower VD (P =.02) were significantly associated with a faster rate of RNFL loss.

Investigators suggest OMAG imaging provides useful information about the risk of glaucoma progression and the rate of disease worsening.

This study has several limitations, including that progression rates of the 2 quadrants of the same eye and 2 eyes of the same patient could be correlated beyond statistical adjustments. Also, some of the parameters evaluated for their association with progressive RNFL loss are common to quadrants (such as IOP and CCT of the same eye) and eyes (like age and gender of the patient) and can be beyond statistical adjustments. Another limitation is that the region of VF (180˚), RNFL quadrant (90˚), OCT-A quadrant (90˚) and GCIPL sector (60˚) used for the analysis in the current study were not the same topographically. Other limitations are that researchers did not analyze the RNFL progression in the temporal quadrant, and that a minimum of 3 OCT examinations performed for a follow-up period of at least 2 years were used to detect the RNFL slope. 

Disclosure: Some of the study’s authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Rao HL, Dasari S, Puttaiah NK, et al. Optical microangiography and progressive retinal nerve fiber layer loss in primary open angle glaucoma. Amer J Ophthalmol. Published online July 24, 2021. doi:10.1016/j.ajo.2021.07.023