Retinal Mid-Peripheral Capillary Free Zones Are Enlarged in Diabetic Patients With No Evidence of Clinical...

To compare the width of the mid-peripheral capillary free zones (CFZs; periarteriole and perivenule) between diabetics with no diabetic retinopathy (DR) versus controls.

The 20° × 20° optical coherence tomography angiography images of paired arterioles, venules, and their adjacent capillaries within the macular and inferomacular regions of the superficial vascular plexus were obtained from 46 eyes of 28 diabetics with no DR (mean age, 59 years; range, 40-71 years) and 46 eyes of 31 controls (mean age, 59 years; range, 46-78 years). There was no significant difference in age between groups (P = 0.77). The macular and inferomacular images were montaged to generate a wider field of view, followed by the application of a vesselness filter and Otsu thresholding. The mid-peripheral CFZ width was calculated using previously established MATLAB algorithms. Generalized linear mixed models were used to compare the mid-peripheral CFZs between groups, accounting for correlation between eyes.

The periarteriole CFZ width was greater in diabetics with no DR (73.3 ± 6.49 µm) compared to controls (67.3 ± 7.08 µm; P < 0.001, Cohen's d = 0.88). Similarly, the perivenule CFZ width was larger in diabetics with no DR (60.8 ± 6.40 µm) compared to controls (54.8 ± 4.58 µm; P < 0.001, Cohens' d = 1.08).

Our results demonstrate larger mid-peripheral CFZ width in diabetics with no DR. The mid-peripheral CFZs show promise as a potential novel retinal vascular biomarker for early DR detection.

Our study shows the potential clinical utility of the mid-peripheral CFZs for early DR detection.