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Vessel density indicates glaucoma severity using OCT-A
Researchers found a significant relationship between vessel density and severity of visual field damage, which suggests that reduced vessel density on OCT angiography is associated with more severe glaucoma, according to study results reported in Ophthalmology.
The study included 31 healthy subjects, 48 glaucoma suspects, 46 patients with mild glaucoma and 28 patients with moderate to severe glaucoma.
Researchers discovered that healthy eyes appeared to have denser capillary networks in the retinal nerve fiber layer (RNFL) compared with eyes with early glaucomatous optic nerve damage, according to researchers.
In advanced stages of glaucoma, a sparser microvascular network was detected, they wrote.
“Significant differences were found comparing the strength of the associations between standard automated perimetry mean deviation (MD) and both OCT-A vascular parameters with the association between mean deviation and RNFL and rim area measurements,” the researchers wrote.
Further significant differences were found between the association of pattern standard deviation with whole-image vessel density (wiVD) and rim area.
Using multivariate linear regression analysis, each 1% decrease in circumpapillary vessel density was associated with a 0.64 dB loss in MD, and each 1% decrease in wiVD was associated with a 0.66 dB loss in MD, according to researchers.
They also suggested that the vascular-functional correlations were stronger than the standard structural-functional relationships, whether comparing linear or nonlinear fitted models. –by Abigail Sutton
Disclosures: Yarmohammadi reported no relevant financial disclosures. Please see the full study for all remaining authors’ financial disclosures.
Perspective
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Our understanding of glaucoma pathophysiology has always been somewhat incomplete.
Optical coherence tomography has truly shaped how we diagnose and manage glaucoma and is based upon a quantitative structure analysis of the retinal nerve fiber layer (RNFL). However, RNFL analysis remains a one-dimensional aspect of the multifactorial changes that occur in glaucoma. OCT-angiography (OCT-A) tackles the vascular aspect of glaucoma with its ability to measure vessel density.
This study implies a significant alteration to the peripapillary vascular network within the NFL in glaucoma patients. The highlight of this paper is that this loss of vascular network density correlates better with visual field loss compared to RNFL thinning.
As noninvasive imaging techniques continue to advance, we are slowly unveiling changes in the retina and optic nerve that accompany glaucoma, creating more ways for us to manage this somewhat mysterious condition. The results of this study show that OCT-A can be yet another clinical tool to help guide us along the glaucoma continuum.