Macular Oxygen Saturation in Glaucoma Using Retinal Oximetry of Visible Light Optical Coherence Tomography: A Pilot Study

Purpose: A cross-sectional pilot study to compare macular oxygen saturation (sO2) and associated clinical measurements between normal and glaucoma subjects and to evaluate whether macular sO2 can be a diagnostic metric for early-stage glaucoma. Methods: Forty-eight eyes of 35 subjects from three groups were included: normal subjects (16 eyes, 10 subjects), suspect/pre-perimetric glaucoma (GS/PPG) subjects (17 eyes, 12 subjects), and perimetric glaucoma (PG) subjects (15 eyes, 13 subjects). We performed retinal oximetry of visible light optical coherence tomography (VIS-OCT) in macular vessels, with 512 x 256 sampling points over a 5 x 5 mm2 area. Zeiss Cirrus OCT scans and a 24-2 visual field test (VFT) were conducted. Statistical analysis was conducted. Results: Significant differences were observed among the three groups for all VIS-OCT, Zeiss OCT, and VFT variables. As glaucoma severity increased, macular AsO2 (arterial sO2) and A-V sO2 (arteriovenous sO2 difference) decreased, whereas macular VsO2 (venous sO2) increased. Macular AsO2 and A-V sO2 were found to be statistically correlated with ganglion cell layer + inner plexiform layer (GCL+IPL) and circumpapillary retinal nerve fiber layer in all eyes, as well as in PG eyes. Within the PG group, a dominant correlation between AsO2 and ganglion cell layer+ inner plexiform layer was observed in the more damaged lower hemifield. Conclusions: Glaucoma subjects showed altered macular sO2, indicating reduced oxygen consumption. The sO2 measured by VIS-OCT could be a potential metric for early glaucoma diagnosis. Translational Relevance: This study shows macular sO2 measurements via VIS-OCT could bridge advanced imaging technology and clinical glaucoma detection.