Oxygen saturation measurements of the retinal vasculature in treated asymmetrical primary open-angle glaucoma using hyperspectral imaging

PurposeTo determine whether there are differences in retinal vascular oxygen saturation measurements, estimated using a hyperspectral fundus camera, between normal eyes and treated eyes of subjects with asymmetrical primary open-angle glaucoma (POAG).MethodsA noninvasive hyperspectral fundus camera was used to acquire spectral images of the retina at wavelengths between 556 and 650 nm in 2-nm increments. In total, 14 normal eyes and both eyes of 11 treated POAG subjects were imaged and analyzed using algorithms that use the spectral variation of the optical densities of blood vessels to estimate the oxygen saturation of blood within the retinal vasculature. In the treated POAG group, each of the eyes were categorized, based on the mean deviation of the Humphrey visual-field analyzer result, as either more-advanced or less-advanced, glaucomatous eyes. Unpaired t-tests (two-tailed) with Welch’s correction were used to compare the mean oxygen saturation between the normal subjects and the treated POAG subgroups.ResultsIn less-advanced and more-advanced-treated POAG eyes, mean retinal venular oxygen saturations (48.2±21.6% and 42.6±18.8%, respectively) were significantly higher than in normal eyes (27.9±9.9%; P=0.03 and 0.01, respectively). Arteriolar oxygen saturation was not significantly different between normal eyes and treated POAG eyes.ConclusionsThe increased oxygen saturation of the retinal venules in advanced-treated POAG eyes may indicate reduced metabolic consumption of oxygen in the inner retinal tissues.