Texture of retinal OCT images as potential biomarker for early diagnosis of diabetic retinopathy: evidence from an animal model of type 1 diabetes

Abstract

Purpose : The diagnosis of diabetic retinopathy (DR) usually occurs many years after diabetes onset. Indeed, an early diagnosis of DR remains a notable challenge, and so the identification of novel biomarkers is of utmost importance. We aim to identify novel early biomarkers for DR based on texture analysis of optical coherence tomography (OCT) retinal images. Previously, we reported significant changes in the retinal texture of an Alzheimer’s disease animal model, comparing to wild-type mice.

Methods : As a proof of concept, we used an animal model (Wistar rats) of type 1 diabetes (T1D), triggered by streptozotocin (65 mg/kg; i.p.). Volume OCT scans (N=40-44) and electroretinograms (N=25) were acquired before and 1, 2, and 4 weeks after diabetes induction. Automated OCT image segmentation was performed, and retinal thickness was computed. Texture analysis was applied to OCT retinal images. Blood-retinal barrier breakdown (tight junction proteins evaluation and Evans blue assay), glial reactivity, neuroinflammation and nitrosative stress were also assessed.

Results : T1D induced significant early changes in several texture features. At week 4, all retinal layers presented a decrease in autocorrelation, information measure of correlation 2 (IMC2), inverse difference moment normalized (IDMN), inverse difference normalized (IDN), and sum average texture metrics. Similar effects were observed for IMC2, IDMN, and IDN, at week 2. Moreover, subtle thinning of the diabetic retinas was detected (weeks 1, 2, and 4), specifically in the inner plexiform and nuclear layers, inner/outer photoreceptor segments, and total retina. Retinal function was altered, with increased latencies in a-wave and oscillatory potentials 1-4 (weeks 1, 2, and 4). Also, an increased number of microglial cells (weeks 1, 2 and 4) and nitrotyrosine immunoreactivity were detected in diabetic retinas (week 4). Claudin-5 (weeks 2 and 4) and occludin (week 4) immunoreactivity decreased in diabetic animals, along with a reduction in claudin-5 protein levels (week 4), although vascular permeability remained unchanged.

Conclusions : Our results show that diabetes induces early significant changes in retinal texture, along with retinal molecular and cellular changes, suggesting that OCT retinal texture can potentially be used for the early diagnosis of DR, but this needs to be confirmed in human studies.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.