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Valeria Duarte Garcia, Kallene Summer Moreira Vidal, Gloria L. Duque-Chica, Mirella Telles Salgueiro Barboni, Balázs V. Nagy, Ana Laura de Araujo Moura, Dora Fix Ventura; Inner and outer retinal losses in non retinopathic type 1 diabetics. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1468.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetes mellitus (DM) is a chronic disease that affects different systems during its progression. Chronic hyperglycemia causes vascular endothelial cell dysfunction, which leads to complications such as diabetic retinopathy (DR). DR may alter visual functions and if not carefully monitored results in blindness. This work investigated contrast sensitivity, Pattern electroretinogram (PERG) and pupillary light reflex (PLR) of patients with type 1 DM in order to know if there are retinal changes prior to the DR.
Nine type 1 DM patients without DR (mean age =30.7±7 years old) were compared to 12 control subjects without diabetes or ocular diseases (mean age =27.9±5). Contrast sensitivity was evaluated with the Metropsis software (Cambridge Research System, Ltd) using vertical sine wave gratings at six spatial frequencies (0.5; 1; 2; 5; 10; 20 cpd). PERGs were recorded using the RetiPort system (Roland Consult, Brandenburg, Germany) according to the ISCEV standard protocol. Four of these type 1 DM patients had their PLR that'll measured with an eye tracker (View Point, Arrington); stimuli were presented in a Ganzfeld (Q450, Roland). Pupil responses were measured monocularly, to 1s blue (470 nm) and red (630 nm) flashes with -3, -2, -1, 0, 1, 2, and 2.4 log cd/m2 luminances. The normalized peak amplitude (PA) of the PLR were measured. Mann-Whitney U test was used for comparison among groups.<br />
Type 1 DM patients presented significantly elevated implicit time of P50 (p=0.041) and N95 (p=0.004) with no difference in the amplitudes (p>0.05). Contrast sensitivity was reduced in the diabetics at 0.5 cpd (p=0.04), no differences were found for other spatial frequencies (p>0.05). The PLR PA for blue stimuli at -3 log cd/m2 was significantly (p=0.01) reduced in patients with DM compared to controls.
Non retinopathic type 1 diabetes mellitus patients have visual losses detectable by psychophysical, electrophysiological and pupillometry tests. Since the magnocellular system mediates sensitivity at spatial frequencies below about 1.5 c/deg , it is possible that ganglion cell dysfunction detected by PERG can be related to the M type or Parasol ganglion cell being cell early affected in type 1 diabetics .In addition our data showed a reduction in the rod contribution to the PLR, suggesting that the outer retina can be also affected in non retinopathic type 1 diabetes.<br />
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