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Marilyn E Schneck, Marcus A Bearse, Wendy Lam, Wayne A Verdon, Ann Chang, Tracy Wang, Shirin Barez, Anthony J Adams; Associations between retinal vessel caliber and ERG oscillatory potentials in adults with and without type 2 diabetes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):483. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Oscillatory potentials (OPs) are often altered in diabetes, even in the absence of diabetic retinopathy (DR), and are predictive of progression to advanced DR. In diabetes, increased retinal vessel caliber (RVC) is predictive of incident DR and also of DR progression. Luu et al. (IOVS 2009) reported that of the many ERG measures examined, only OP4 amplitude (AMP) was associated with RVC in type 2 diabetes. We re-examine potential associations between RVC and OP AMP and between RVC and OP implicit time (IT).
90 subjects in 4 groups participated: 34 non-diabetic controls (NC); 28 with diabetes and no DR (NoDR); 20 with diabetes and non-proliferative DR (NPDR); 8 with diabetes and NPDR + macular edema (DME). The 3 diabetes groups were also considered as a single group (DM; n=56). ERGs were recorded using bipolar electrodes following pupil dilation and 20 minutes dark adaptation with an LKC system. OPs were extracted from ERGs elicited by ISCEV scotopic 3.0 ERG. Cursors were manually placed to determine the AMP and IT of OP 1 through 4. Retinal vessel calibers [arteriole caliber (ArtC ), venule caliber (VenC), and arteriole to venule ratio (AVR)] were determined using IVAN software. The association between each of the vessel measures and the AMP and IT of OP 1 through 4 was determined using Spearman rank-order correlations. Criterion for significance was p<0.005.
VenC was significantly larger and AVR was smaller in DM than in NC. ArtC did not differ among groups.<br /> AMP findings: In the NC group, VenC was positively correlated to the AMP of OP1, OP2, and OP3, but not OP4 (p=0.607). There was no association between VenC and OP AMP for any diabetic group nor for all DM. ArtC and AVR were not significantly associated with OP AMP in any subject group.<br /> IT findings: In NC only OP3 IT was inversely associated with ArtC and with VenC. For DM, IT of OP1, OP2, and OP3 were inversely associated with ArtC, but not with VenC. No associations of AVR and OP IT were seen in any group.
In non-diabetics, OP AMP is directly related to venule caliber, an association that appears to be absent in diabetes even in the absence of DR. In DM, at least in the absence of abnormal arteriole enlargement, shorter OP IT is associated with larger arteriole caliber. Our results differ from those of Luu et al. who examined fewer subjects with Type 2 diabetes.
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