Abstract
Purpose :
To assess retinal blood flow velocity measurements using the XyCAM RI in healthy subjects, individuals with Type 2 Diabetes (T2D) (no Diabetic Retinopathy), and subjects with mild-to-moderate Non-Proliferative Diabetic Retinopathy (NPDR).
Methods :
Twenty-one eyes of 12 subjects (4 healthy, 4 T2D, 4 NPDR) were imaged using the XyCAM RI. An imaging session consisted of the serial acquisition of laser speckle images of the retina centered on the optic disc at 82 frames/second over a six-second duration, with simultaneous acquisition of heart rate, blood oxygen levels, and pulse waveforms using a pulse oximeter. The Blood Flow Velocity index (BFVi – arbitrary units) was averaged over all pixels in major artery and vein segments outside of the Optic Disc across the six seconds of data. The average BFVi measurement for all arteries and veins was normalized to heart rate and compared across each patient group at diastolic (trough), mean, and systolic (peak) flow (Figure 1). Two sample t-tests were used to determine any significant differences in flow metrics across the different patient groups.
Results :
The mean BFVi in healthy, T2D and NPDR subjects was 16.02 ± 2.40, 15.84 ± 1.79, and 11.73 ± 3.49 in arterial segments and 16.57 ± 3.22, 16.44 ± 2.20, and 11.80 ± 2.52 in venous segments, respectively (Figure 1e). The BFVi measurements in both arteries and veins were significantly lower in NPDR eyes compared to T2D eyes (pairwise p<0.05) across the entire cardiac cycle as well as in NPDR eyes compared to healthy eyes (pairwise p<0.05) except in arteries at systole (Figure 2). No significant differences in BFVi measurements were observed when comparing healthy to T2D eyes (all p>0.28).
Conclusions :
Retinal blood flow velocity measurements have been shown to be significantly lower in eyes with NPDR than in eyes that are healthy or without retinopathy despite diabetes, providing preliminary evidence of the suitability of this method for diagnosing the onset of NPDR.
This is a 2020 ARVO Annual Meeting abstract.