Characterizing the disorganization of the retinal inner layers in diabetic retinopathy: using a new high-resolution optical coherence tomography device

Abstract

Purpose : The Disorganization of the Retinal Inner Layers (DRIL) is an accepted optical coherence tomography (OCT) biomarker in the assessment of diabetic retinopathy (DR), and is highly associated with visual outcome. New high-resolution OCT (High-Res OCT) significantly enhances axial resolution and, therefore, enables a more detailed analysis of the retinal layers (PMID: 37106625). Here, we use High-Res OCT to characterize DRIL in DR patients in a prospective, cross-sectional clinical study.

Methods : Patients with diabetes type 1 or 2 underwent multimodal retinal imaging (common spectral domain (SD)-OCT, High-Res OCT [30×25°, ART 25, 241 B-scans, 30µm distance] and color fundus photography). Furthermore, duration of diabetes, HbA1c, and cardiovascular risk factors were recorded. DR was graded using the international clinical DR severity scale (DRSS) (PMID:13129861). In each OCT B-scan, retinal layers were segmented and the loss of discernibility of the individual layers were annotated and then, projected in an en face view, and the DRIL areas measured and set in relation to the position of the ETDRS grid using FIJI plugins.

Results : In 108 eyes of 90 patients (age 63.4±12.7 years; diabetes type I (n=14), II (n=76); duration of diabetes: 16.3±11.3 years; mean HbA1c: 7.3±1.2%), 52 eyes with DRIL were identified. 92.3% of DRIL were located in the ETDRS central subfield. In DRIL eyes, DRSS was significantly higher compared to non-DRIL eyes (4.2±1.1 vs. 2.7±1.6, p<0.001). In the en face view, DRIL area was largest in the retinal nerve fiber layer (2.92±3.82mm²), followed by ganglion cell (2.37±3.03mm²), inner nuclear (1.12±1.48mm²) and inner plexiform layers (1.04±1.29mm²). There was strong tendency for smaller DRIL area in High-Res OCT as compared to SD-OCT (0.21±0.19 vs. 0.39±0.33 mm²; p=0.05).

Conclusions : DRIL appear to develop especially in eyes with more advanced diabetic retinopathy/maculopathy with a newly described characteristic spread: from the inner towards the outer retina. High-Res OCT allows a more precise delineation of the DRIL areas. Longitudinal studies including functional testing are underway to further deepen our understanding of DRIL and its impact on DR progression and treatment strategies.

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