Retinal Layer Location of Increased Retinal Thickness and Retinal Thinning on the cohort of the EUROCONDOR clinical trial

Abstract

Purpose : To identify the involvement of the different retinal layers in subclinical and center-involving macular edema in a large cohort type 2 diabetic eyes with early diabetic retinopathy (DR) or without DR.

Methods : A cohort of 449 type II diabetic eyes/patients with mild non-proliferative DR (ETDRS levels 20 or 35), 57% of eyes, or without DR (ETDRS level 10), 43% of eyes, (EUROCONDOR clinical trial, NCT01726075) were examined with SD-OCT at the baseline visit. Automated segmentation of the retinal layers was compared with a sample of 58 healthy eyes from a control group.

Results : From the 449 eyes of the study 48% had normal baseline full retinal thickness, 30% had subclinical macular edema and 5% had center-involving macular edema, using the DRCR.net parameters. The highest increases in retinal thickness (RT) were found in the inner nuclear layer (INL; 53% in subclinical macular edema, p<0.001 and 91% in center-involving macular edema, p<0.001). Statistically significant increases (p<0.001) were also found in the immediately neighboring layers (GCL+IPL and ONL) on patients with subclinical and center-involving macular edema. Thinning of the retina was registered in the RNF and OS layers in the diabetic eyes with normal full retinal thickness at baseline.

Conclusions : The increase in RT occurring in diabetic eyes with different degrees of macular edema is predominantly located in the INL but extends to immediately neighboring retinal layers indicating that it may be due to extracellular fluid accumulation resulting from increased vascular permeability in the retinal deep capillary layer.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.