Abstract
PurposeTo validate retinal capillary density and caliber associations with diabetic retinopathy (DR) severity in different clinical settings.MethodsThis cross-sectional study assessed retinal capillary density and caliber in the superficial retinal layer of 3-mm OCTA scans centered on the fovea. Images were collected from non-diabetic controls and subjects with mild or referable DR (defined DR worse than mild DR) between February 2016 and December 2019 at secondary and tertiary eye care centers. Vessel Skeleton Density (VSD), a measure of capillary density, and Vessel Diameter Index (VDI), a measure of vascular caliber, were calculated from these images. Discriminatory performance of VSD and VDI was evaluated using multivariable logistic regression models predicting DR severity with adjustments for sex, hypertension, and hyperlipidemia. Area under the curve (AUC) was estimated. Model performance was evaluated in two different cohorts.ResultsThis study included 594 eyes from 385 subjects. Cohort 1 was a training cohort of 509 eyes including 159 control, 155 mild non-proliferative DR (NPDR) and 195 referable DR eyes. Cohort 2 was a validation cohort consisting of 85 eyes including 16 mild NPDR and 69 referable DR eyes. In Cohort 1, addition of VSD and VDI to a model using only demographic data significantly improved the model’s AUC for discrimination of eyes with any DR severity from controls (0.91 [95% CI, 0.88–0.93] versus 0.80 [95% CI, 0.76–0.83], p < 0.001) and eyes with referable DR from mild NPDR (0.90 [95% CI, 0.86–0.93] versus 0.69 [95% CI, 0.64–0.75], p < 0.001). The transportability of this regression model was excellent when implemented in Cohort 2 for the referable DR versus mild NPDR comparison. The odds ratio of having any DR compared to control subjects, and referable DR compared to mild DR decreased by 15% (95% CI: 12–18%), and 13% (95% CI: 10–15%), respectively, for every 0.001 unit increase in VSD after adjusting for comorbidities.ConclusionOCTA-derived capillary density has real world clinical value for rapidly assessing DR severity.
Highlights
Diabetic retinopathy (DR) is one of the world’s leading causes of blindness [1] and its prevalence may be underestimated [2]
In Cohort 1, addition of Vessel Skeleton Density (VSD) and Vessel Diameter Index (VDI) to a model using only demographic data significantly improved the model’s Area under the curve (AUC) for discrimination of eyes with any DR severity from controls (0.91 [95% CI, 0.88–0.93] versus 0.80 [95% CI, 0.76–0.83], p < 0.001) and eyes with referable DR from mild non-proliferative DR (NPDR) (0.90 [95% CI, 0.86–0.93] versus 0.69 [95% CI, 0.64– 0.75], p < 0.001)
The odds ratio of having any DR compared to control subjects, and referable DR compared to mild DR decreased by 15%, and 13%, respectively, for every 0.001 unit increase in VSD after adjusting for comorbidities
Summary
Diabetic retinopathy (DR) is one of the world’s leading causes of blindness [1] and its prevalence may be underestimated [2]. The current gold standard for clinical diagnosis and management of DR is the International Clinical Diabetic Retinopathy (ICDR) and Diabetic Macular Edema (DME) disease severity scales [5] All of these scales rely on ophthalmoscopically visible changes in fundus appearance for staging. Optical coherence tomography angiography (OCTA)—a commercially available, FDA approved, and noninvasive imaging technique—can capture these subtle capillary changes [6,7,8,9,10,11,12,13,14] As a result, it may be useful in evaluating DR severity where access to ophthalmologists is limited and in early stages of disease when invasive fluorescein angiography is neither available nor indicated
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