Electrophysiological changes in type I diabetes without retinopathy

ABSTRACT

To assess early functional retinal changes in type I diabetic children and adolescents with no ophthalmoscopically detectable retinopathy. Oscillatory potentials [OP's], scotopic and photopic electoretinogram [ERG] were studied. To study the relationship between ERG and systemic risk factors of retinopathy. Recognition of these early neurosensory defects will enhance our understanding of the pathophysiological basis of diabetic retinopathy. Eighty six type 1 diabetic children and adolescents without ophthalmoscopically detectable retinopathy were evaluated and thirty normal subjects were served as control. Flash ERG examination was carried out using Nihon Kohden Neuopack 2 [Japan]. The stimulator used was a flash stimulator [Xenon tube] SLS-3100 [Nihon Kohden]. Performing the oscillatory potentials [OPs], scotopic and photopic responses recording its amplitude in micro V and peak implicit time in msec. The differences between control subjects and diabetics were assessed. Serum lipid profile, HbA1c% and screening for microalbuminuria were performed. Oscillatory potentials were delayed. Significantly reduced amplitudes and component-specific delayed peak implicit times were found in the diabetic group compared with the data from the controls. Similar results were obtained in the photopic and scotopic electroretinogram. ERG findings were correlated with poor glycemic control and dyslipidemia. From these findings, we concluded that retinal dysfunction is already present in type 1 diabetics without ophthalmological evidence of retinopathy after a mean duration of diabetes of 7.5 years