Patients With Diabetic Retinopathy and Neuropathy Showed Lower Amplitudes on the Multifocal Vep Than Diabetic Patients With the Same Level of Retinopathy but No Neuropathy

Abstract

Purpose:: The purpose of the present study was to determine whether diabetic patients with neuropathy demonstrated more signs of altered neural function in the visual pathways measured with multifocal visual evoked potential (mfVEP) and multifocal electroretinography (mfERG) than patients without neuropathy, but with the same degree of retinopathy.

Methods:: Thirty-two diabetic patients with diabetic retinopathy and with (n=18) and without (n=14) clinical neuropathy were examined with mfVEP and mfERG and compared. Ten healthy persons without diabetes were also included for comparison.The VERIS multifocal ERG system was used and a pattern stimulation were displayed on a screen in the IR camera, which was further used for controlling fixation. A two channels system was applied for recording from separate cortical areas.

Results:: Diabetic duration, and the number of patients who had underwent panretinal photocoagulation were similar in patients with and without neuropathy; 29±13 vs. 25±7 years, p=0.3, but age differed; 59±7 vs. 46±9 years, p<0.01.The mfVEP amplitudes were higher in the response from one cortical local segment (N1) in the right side 35 ± 15 vs. 24 ± 16 nV/ deg²; p=0.020 and in two response areas (N1,N5) from the left side 33 ± 15 vs. 21 ± 9 nV/ deg² ;p= 0.008 and 34 ± 13 vs. 24 ± 15 nV/ deg² ;p= 0.045 in patients without neuropathy compared to patients with neuropathy.Repeated measure analysis of variance from only the left eye showed higher amplitudes in the mfERG in all the five rings measured in patients without neuropathy compared to patients with neuropathy, even when adjusted for age p=0.022. No differences were seen in implicit time between patients with or without neuropathy.Patients without diabetes had the same age as patients with diabetes 48±vs 56± years, p=0.052). They showed higher amplitudes on the mfVEP in all the registered recordings compared to patients with diabetes; p values from <0.001-0.022).

Conclusions:: Previously not shown this study support that mfVEP could be an indicator of optic nerve neuropathy in patients with diabetic retinopathy and that there is a correlation between this dysfunction and diabetic neuropathy. The early optic nerve involvement might explain some of the visual complain in this group.

Keywords: diabetic retinopathy • electrophysiology: clinical • optic nerve