Electrophysiological assessment of visual function in newlydiagnosed IDDM patients

Abstract

Electrophysiological tests (electroretinogram, oscillatory potentials, visual evoked potentials, in the basal condition and after photostress) reveal an abnormal function of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess whether electrophysiological abnormalities in visual function exist in newly-diagnosed diabetic patients free of any fluorangiographic signs of retinopathy. Ten control subjects (age 28.7 +/- 2.44 years) and then IDDM patients (age 25.2 +/- 6.78 years; disease duration 5.3 +/- 3.5 months) in stable metabolic control (HbA1C 7.5 +/- 1.1%) were evaluated. Flash-electroretinograms and oscillatory potentials were similar in both groups. Visual evoked potentials (VEP) recorded under basal conditions showed that P100 latency was significantly increased in the diabetic patients compared to control subjects (p < 0.01), while N75-P100 amplitude was similar in both groups. The recovery time of VEP after photostress was equivalent in diabetic patients and control subjects. The impaired basal VEPs suggest an early involvement of the nervous conduction in the optic nerve. However, the preserved flash-electroretinogram and the normal recovery time after photostress indicate that a short disease duration does not induce physiopathological changes in the outer retinal layers or in the macular function.

Visual-evoked potentials in children and adolescents with newly diagnosed diabetes

“…These data are in agreement with those reported in young persons with newly diagnosed insulin-dependent diabetes (3)(4)(5). Their studies included 30 (mean age: 17.6 years), 14 (mean age: 24.8 years), and 10 patients (mean age: 25.2 years) with insulin-dependent diabetes mellitus, respectively.…”

“…Visual-evoked potential (VEP) recordings represent a mass response of cortical and probably subcortical visual areas, and are used to assess the functional integrity of the visual pathway (2). The literature dealing with VEP findings in newly diagnosed young patients with diabetes is very limited (3)(4)(5).…”

Visual evoked potentials in young persons with newly diagnosed diabetes: a long‐term follow‐up

“…This impairment appears early during the history of the disease. In recent years some authors (Uccioli et al 1995, Parisi et al 1997 have shown that these alterations are not present at the onset of diabetes, but occur only after the disease has been present for a mean of at least 3.3 years. On the contrary, we can confirm that VEP abnormalities after photostress are present and detectable in children with newly diagnosed diabetes, with no signs of retinopathy and/or peripheral and/or autonomic neuropathy.…”

“…To the best of our knowledge, only one study (Uccioli et al 1995) has investigated the prevalence of electrophysiological abnormalities in visual function in patients with newly diagnosed diabetes, and there are no data concerning children and adolescents at onset of IDDM.…”

Glial and neuronal dysfunction in streptozotocin-induced diabetic rats

“…More recent studies using the multifocal ERG show that local timing delays can predict those patches of retina that will go on to develop nonproliferative diabetic retinopathy [7,8]. Thus, in general, studies suggest that functional responses arising from postreceptoral pathways, such as oscillatory potentials [9], the photopic negative response [10] and the visual evoked potential [9], decline before outer retinal responses in the course of diabetic eye disease. In agreement with the physiology, anatomical and imaging studies in human diabetes show that the loss of inner retinal neurons (in particular the retinal ganglion cells) and a thinning of the retinal nerve fibre layer can occur early in diabetes [11][12][13].…”