Abstract
Purpose :
Diabetic retinopathy (DR) causes both vascular and photoreceptor abnormalities. This study is to test if photoreceptor change occurs before detectable vascular abnormality in early DR.
Methods :
OCTA and OCT images were acquired from normal eyes, and diabetic eyes with no DR and with mild DR. Four OCTA features were quantified, including vessel diameter index (VDI), tortuosity index (VTI), perimeter index (VPI), and complexity index (VCI). Analogously, four OCT features from outer retina were quantified, including intensities of the external limiting membrane (ELM), inner segment ellipsoid (ISe), retinal pigment epithelium (RPE), and the normalized ISe/RPE intensity ratio. Quantitative OCTA features were analyzed on the superficial vascular plexus (Fig. 1a) including corresponding vessel, skeleton, and perimeter (Fig. 1b-d), and OCT features were analyzed using averaged A-line intensities from the OCT B-scans (Fig. 1e) in the parafoveal and perifoveal regions.
Results :
Two quantitative OCTA features, VDI and VCI, were observed to have significant differences (p<0.05) among the healthy and diabetic eyes (no DR and mild DR). However, OCTA features did not reveal any significant differences between no DR and mild eyes. In contrast, for OCT features, the ISe intensity revealed significant differences (p<0.05) between non-diabetic eyes (healthy and no DR) and mild DR eyes. Quantification of ISe/RPE intensity ratio improved the sensitivity for differentiation among cohorts (p<0.001) in the parafoveal region.
Conclusions :
Quantitative OCT analysis revealed higher sensitivity for differentiation of healthy, no DR, and mild DR eyes compared to OCTA features. This study suggests that abnormalities of the outer retina occur before vascular abnormalities in early DR. The normalized ISe/RPE measurement promises a sensitive biomarker for objective detection of early DR.
This is a 2021 Imaging in the Eye Conference abstract.