# Increased axial resolution OCT improves structure-function correlation of the disorganization of the retinal inner layers in diabetic retinal disease

## TL;DR

Higher-resolution OCT improves detection of retinal layer disorganization in diabetic retinal disease and better links it to vision loss and blood vessel changes.

## Contribution

Enhanced axial resolution OCT provides more accurate structure-function correlation in diabetic retinal disease.

## Key findings

- DRIL areas measured smaller with High-Res OCT compared to SD-OCT (0.3 mm² vs. 1.3 mm²).
- Retinal sensitivity decreases progressively from zones with DRIL on both OCT types to unaffected retina.
- OCTA showed persistent vascular differences between DRIL and non-DRIL eyes, independent of retinopathy severity.

## Abstract

This study aimed to determine whether optical coherence tomography (OCT) with enhanced axial resolution improves structural characterization of the disorganization of the retinal inner layers (DRIL) in diabetic retinal disease (DRD) and its association with functional and vascular alterations. In this prospective cross-sectional study, 55 diabetic patients, 27 with DRIL (age: 57.1 ± 14.6 years) and 28 eyes without DRIL with diabetes mellitus (DM) type I/II (age: 58.2 ± 13.0 years), were examined with conventional spectral-domain OCT (SD-OCT), High-Resolution (High-Res) OCT, OCT angiography (OCTA), and microperimetry. DRIL areas were significantly smaller on High-Res OCT compared to SD-OCT (mean ± standard deviation, 0.3 ± 0.3 vs. 1.3 ± 1.2 mm2, p < 0.001). OCTA analyses demonstrated persistent group differences in superficial and deep vessel density and FAZ circularity between DRIL eyes and eyes without DRIL, even after adjustment for clinical diabetic retinopathy severity score (DRSS, all p < 0.05). Within DRIL eyes, intra-eye analysis revealed a stepwise reduction in retinal sensitivity from areas with DRIL detected on both OCT modalities (Zone I: 13.1 ± 1.3 dB) to areas with DRIL only on SD-OCT (Zone II: 20.6 ± 0.8 dB) and to unaffected retina (Zone III: 23.1 ± 0.7 dB, overall p < 0.001). OCT with enhanced axial resolution refines DRIL detection, aligning more precisely with localized functional and vascular impairment.

The online version contains supplementary material available at 10.1038/s41598-025-34931-2.