Subclinical changes detected in diabetes mellitus using high resolution retinal imaging and colour vision assessment

Abstract

Purpose : Diabetic retinopathy (DR) is the leading cause of vision loss in working-age adults in the developed world. Although it is known that photoreceptor damage and color vision loss occur in patients with diabetes mellitus (DM), the relationship between these structural and functional changes remains unclear. By using highly sensitive measures of photoreceptor structure and function, we aim to determine whether early loss of color sensitivity in DM is also accompanied by decreased cone density

Methods : Monocular data from 25 patients with DM and varying severity of DR, along with 25 normally-sighted controls without DM, were examined to assess the integrity of their cone photoreceptors and their red/green (RG) and yellow/blue (YB) color vision. The retina was imaged using a custom-built adaptive optics scanning light ophthalmoscopy (AOSLO) system. Cone density was assessed, when possible, using confocal images from 0.5 and 1 degree eccentricity along the temporal meridian (0.5T, 1T) using 55 x 55 μm regions of interest. Color vision was assessed using the Colour Assessment and Diagnosis (CAD) test, which yields both RG and YB color detection thresholds

Results : Both RG and YB thresholds were significantly greater in patients with DM than in controls (RG: p<0.001; YB: p<0.001), and there were statistically significant differences in confocal cone density between the two groups at 1T (p=0.016), but not at 0.5T (p=0.094). In patients with DM, cone density at 1T was inversely correlated with RG and YB chromatic discrimination thresholds (RG: p=0.014; YB: p=0.007), whereas for 0.5T only YB was correlated with cone density (p=0.009), and not RG (p=0.152). No relationship between RG and YB chromatic discrimination thresholds and cone density was evident in the control group for 0.5T (RG: p=0.808; YB: p=0.693) nor 1T (RG: p=0.874; YB: p=0.166).

Conclusions : Although the CAD test and AOSLO are currently being used as outcome measures in clinical trials for gene therapy, they have not been validated against each other. This is the first study to investigate the relationship between cone density and colour detection in patients with DM. The significant inverse relationship observed between cone density and CAD thresholds could have important implications for understanding retinal structure-function relationships in DM, potentially providing a valuable screening tool for early detection of DR

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.