Abstract
Purpose :
To quantify blood flow within the optic nerve head using the XyCAM RI, a non-invasive, laser speckle-based retinal imager in glaucoma, glaucoma suspect, and non-glaucomatous subjects.
Methods :
Sixteen subjects (4 controls, 6 glaucoma suspect, 6 with moderate to severe glaucoma) were imaged using the XyCAM RI, an investigational device. Intraocular pressure, and blood pressure measurements were collected prior to imaging and heart rate and oxygen saturation were captured during image acquisition. Four imaging sessions, each of 6 seconds duration, were conducted on each subject. Retinal blood flow (RBF) was computed in a region spanning all vessels overlying the optic nerve head (ONH), and a region spanning the area of disk perfusion with the vessels excluded (Figure 1.). RBF was determined for each complete cardiac cycle at its trough, mean, and peak and averaged over the number of cardiac cycles for each session that were recorded. ANOVA and independent sample t-test were used to determine significance of differences in RBF between patient type.
Results :
RBF, reported in arbitrary units, was significantly lower in patients with confirmed glaucoma versus those without over the entire cardiac cycle. Specifically, mean disk perfusion for controls and glaucoma suspects was 4.99 ± 0.50, and was 4.07 ± 0.73 for subjects with moderate to severe glaucoma (P <0.01, independent samples t-test). Disk perfusion RBF was significantly lower in glaucoma subjects versus glaucoma suspect (P < 0.05) and disk vessel RBF was significantly lower in glaucoma subjects versus glaucoma suspect and controls independently (P <0.01, P <0.05 respectively) over the entire cardiac cycle (Table 1).
Conclusions :
Non-invasive blood flowing imaging of the optic nerve head shows promise in potentially distinguishing between patients with and without glaucoma and should be investigated as a potential biomarker for classifying status and severity of glaucoma.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.