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OCT angiography with projection resolution algorithm quantifies retinal vessel density
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COLORADO SPRINGS, Colo. — Using OCT angiography and a novel “projection resolution and reflectance compensation” algorithm to remove artifact and signal effects, David Huang, MD, PhD, and colleagues found that glaucoma preferentially affects vessel density in the ganglion cell complex more than in deeper layers, according to a study presented at the American Ophthalmological Society meeting here.
“This year I want to talk about studying the macula in the context of glaucoma,” Huang said. “Our technology has moved ahead so that our algorithm is a little bit different now. OCT angiography is great. At first you’re amazed at the information you have, but then you are bothered by the many artifacts. ... [O]ur effort now is getting rid of these artifacts.”
David Huang
Huang said the most important artifact in this context is the projection artifact, which represents moving blood cells in the superficial retina that produce shadows that are interpreted as flow, impeding the ability to visualize deeper layers of the retina. As well, signal artifact affects calculation of vessel density.
Huang and colleagues applied the compensation algorithms and used OCT angiography (AngioVue, Optovue) to study 30 eyes of 30 patients with perimetric glaucoma; 10 had mild disease, 15 had moderate disease, and five had advanced disease. Thirty age-matched controls were also studied.
In the superficial plexus, there was a statistically significant decrease of 22% in vessel density between the control group and the glaucoma group (P < .001). In the intermediate and deep layers, vessel density was decreased by 8% and 13%, respectively.
“Glaucoma does affect vessel density in all three plexuses, mostly in the superficial plexus,” Huang said.
Huang and colleagues also found that reflectance compensation improves reliability of vessel density measurement, macular retinal perfusion can be quantified with high repeatability, and superficial vessel density has high diagnostic accuracy and is well correlated with glaucoma severity as measured by visual field. – by Patricia Nale, ELS
Reference:
Huang D. Angiography of macular circulation in glaucoma. Presented at: American Ophthalmological Society; May 19-22, 2016; Colorado Springs, Colo.
Disclosure: Huang reports financial interest in OCT and OCT angiography technology with Optovue and previously with Carl Zeiss Meditec.