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A. A. Reis, C. A. Mateus, P. Melo, M. Castelo-Branco; Visual Function Impairment in the Absence of Diabetic Retinopathy in Type I Diabetes Mellitus. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5058.
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To characterize visual function in type I diabetic patients with preserved visual acuity (VA), with and without early diabetic retinopathy (DR).
Visual function was assessed by Multifocal Electroretinography (RetiScan - Roland Consult), Colour Vision (CCT - Cambridge Research Systems) and Frequency-Doubling Perimetry (FDT - Zeiss) in a population of 42 patients (age=26.6+5.3 years) divided into 2 groups: without DR (n=26; VA=1.088+0.128) and with mild nonproliferative DR (n=16; VA=1.093+0.137). Fluorescein angiography was also performed in order to determine the absence or presence of initial vascular lesions. These data were compared with age-matched controls. Non-parametric statistical analysis was performed at a significance cut-off level of p<0.05.
MfERG yielded a significant decrease in amplitude in all eccentricity rings in both patients groups, when compared with control subjects (p<0.0001). Impaired contrast sensitivity along protan, deutan and tritan chromatic axes (0.0001<p< 0.02) was also observed, except for the Deutan axis which was comparable to performance controls in the group without DR. FDT quadrantic thresholds were also different between controls and patients (0.0009<p<0.002). However, only electrophysiological measures were found to be distinct between patients groups (p=0.04 for all eccentricity rings except the central one), as well as the Deutan contrast sensitivity (p=0.005).
Impairment in visual function can be observed in type I diabetic patients with preserved VA, even with no clinical signs of DR, suggesting that retinal neuronal changes may also be relevant, even before breakdown of the blood-retinal barrier or onset of vasculopathy.
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