Functional and Structural Findings of Neurodegeneration in Early Stages of Diabetic Retinopathy: Cross-sectional Analyses of Baseline Data of the EUROCONDOR Project

Abstract

This cross-sectional study evaluated the relationship between ) functional and structural measurements of neurodegeneration in the initial stages of diabetic retinopathy (DR) and) the presence of neurodegeneration and early microvascular impairment. We analyzed baseline data of 449 patients with type 2 diabetes enrolled in the European Consortium for the Early Treatment of Diabetic Retinopathy (EUROCONDOR) study (NCT01726075). Functional studies by multifocal electroretinography (mfERG) evaluated neurodysfunction, and structural measurements using spectral domain optical coherence tomography (SD-OCT) evaluated neurodegeneration. The mfERG P1 amplitude was more sensitive than the P1 implicit time and was lower in patients with Early Treatment of Diabetic Retinopathy Study (ETDRS) level 20-35 than in patients with ETDRS level <20 ( = 0.005). In 58% of patients, mfERG abnormalities were present in the absence of visible retinopathy. Correspondence between SD-OCT thinning and mfERG abnormalities was shown in 67% of the eyes with ETDRS <20 and in 83% of the eyes with ETDRS level 20-35. Notably, 32% of patients with ETDRS 20-35 presented no abnormalities in mfERG or SD-OCT. We conclude that there is a link between mfERG and SD-OCT measurements that increases with the presence of microvascular impairment. However, a significant proportion of patients in our particular study population (ETDRS ≤35) had normal ganglion cell-inner plexiform layer thickness and normal mfERG findings. We raise the hypothesis that neurodegeneration may play a role in the pathogenesis of DR in many but not in all patients with type 2 diabetes.

Effects of Topically Administered Neuroprotective Drugs in Early Stages of Diabetic Retinopathy: Results of the EUROCONDOR Clinical Trial

“…Each patient underwent a comprehensive ophthalmic examination as previously reported (15). Only one eye from each patient was included in the study.…”

“…Eligibility criteria were age between 45 and 75 years, a diagnosis of type 2 diabetes with a known duration $5 years, and an Early Treatment for Diabetic Retinopathy Study (ETDRS) level of #35. Exclusion criteria were previously detailed (15).…”

“…The mfERGs were recorded in the study eye using the RETI-port/scan21 (Roland Consult, Berlin, Germany) visual electrophysiology system. Detailed information regarding the methodology used has been previously reported (15).…”

“…A total of 284 patients underwent CIRRUS HD-OCT imaging, and 165 patients underwent Topcon 3D-OCT 2000 imaging. Further details on the methodology have been previously reported (15).…”

Diagnosis and treatment of diabetic retinopathy — historical overview

“…However, neurodegeneration is not a dominant pathogenic factor in all patients. What is more, diabetic retinopathy develops in diabetic patients in various manners, and its three phenotypes have been differentiated depending on progression and risk of vision loss [94,95]. Following the revolution in pathogenesis, there appear new possibilities in treatment of diabetic retinopathy.…”