Oxygen Saturation of Macular Vessels in Glaucoma Subjects Using Visible Light Optical Coherence Tomography

Abstract

Purpose : Oxygen saturation (sO₂) played a critical a role in retinal pathophysiology, especially at the macula undertaking the large energy consumption. It has been suggested that macular damage is involved in early-stage glaucoma, but there is no report so far on non-invasive macular sO₂ in glaucoma or any other retinal conditions. Therefore, we conducted this study to compare macular sO₂ between normal and glaucoma subjects and evaluate whether there is significant difference.

Methods : We used visible light optical coherence tomography (VIS-OCT) to enable retinal oximetry in perifoveal vessels. We imaged the subjects from groups of normal, suspect/preperimetric glaucoma (GS/PPG) and perimetric glaucoma (PG) using the VIS-OCT in the macular region with a sampling density of 512×256 in an area of 5×5 mm². 48 eyes (16 normal, 17 GS/PPG and 15 PG) were included for the analysis. For each eye, we measured the sO₂ of arterioles (AsO₂), venules (VsO₂), and calculated the difference between arterioles and venules (A-VsO₂=AsO₂-VsO₂), oxygen extraction (OEsO₂=((AsO₂-VsO₂)/AsO₂) *100%). We also included the thickness of ganglion cell complex (GCC) and circumpapillary retinal nerve fiber layer (cpRNFL) by Zeiss OCT and mean deviation (MD) from 24-2 visual field test for correlation. One-way ANOVA with multiple comparisons was used to compare the differences of AsO₂, VsO₂, A-VsO₂, OEsO₂, GCC and cpRNFL among the three groups. Spearman correlation tests were used to correlate sO₂ markers to GCC, cpRNFL and MD.

Results : Figure 1 demonstrated the statistical comparisons among three groups. The significant differences were found between the normal and PG for all variables. Between normal to the GS/PPG eyes, all sO₂ parameters except AsO₂ showed significant difference. Between GS/PPG and PG, only GCC and cpRNFL had the significance. Table 1 summarized the correlations for the key measurements within PG eyes. GCC and cpRNFL were both statistically correlated with AsO₂ and A-VsO₂. Correlation between GCC and cpRNFL was also found. No correlations were found between MD and other parameters.

Conclusions : The GS/PPG and PG subjects had significant higher VsO₂, lower A-VsO₂ and OEsO₂ indicating the less oxygen consumption. The sO₂ can be a potential metric for the early diagnosis of glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

 

Table 1 Correlations for key measurements in glaucoma subjects.