Session Title: Vascular Diseases and Diabetic Retinopathy III
Session Date/Time: Saturday 19/09/2015 | 16:30-18:00
Paper Time: 17:02
First Author: : N.Goel INDIA
Co Author(s): : A. Prakash A. Gupta
PURPOSE:To characterize the electroretinographic response of the macula by multifocal electroretinography (MF-ERG) in patients with nonproliferative diabetic retinopathy (NPDR) with and without clinically significant macular edema (CSME) and correlate it with visual acuity and retinal thickness on spectral domain optical coherence tomography (SD-OCT).
The study was conducted at a tertiary eye care center from December 2013 to July 2014.
A prospective study of MF-ERG in 40 patients with NPDR with and without CSME without any previous treatment was conducted. All patients underwent recording of best corrected Snellen visual acuity (BCVA), fundus fluorescein angiography (FFA) and SD-OCT. Group A was classified as 20 eyes having NPDR with central foveal thickness (CFT) ≥ 275 µm on SD-OCT while Group B was classified as 20 eyes having NPDR with CFT < 275 µm. The first-order kernel MF-ERG responses recorded using RETI Port/Scan 21 (Roland Consult, Germany), according to ISCEV guidelines, were analyzed. Individual MF-ERG responses for the hexagons were grouped into concentric rings centered on the fovea for analysis (2°, 2–5°, 5–10°, 10–15°, > 15°). Statistical significance was determined by Chi-square/Fishers exact test and unpaired t-test. Correlation between the parameters was determined by Pearson correlation coefficient (r).
40 eyes of 22 patients with NPDR were evaluated, group A and B each containing 20 eyes. The mean BCVA of Group A was 0.45 ± 0.22 and Group B was 0.60 ± 0.26 (p=0.048). Mean CFT and MMT (mean macular thickness) were 368.90±86.54 µm and 234.95±21.56 µm and 355.14±57.63 µm and 286.31±20.85 µm in Group A and Group B respectively. Mean P1 and N1 amplitudes (nv/deg2) were significantly decreased as compared to normal values in each of the 5 rings in both groups (p<0.01); however the values between the two groups were comparable. BCVA was significantly and positively correlated with P1(r=0.454, p=0.003) and N1 amplitude (r=0.468, p=0.002) and significantly and negatively correlated with P1(r= -0.534, p<0.01) and N1 implicit times (r= -0.570, p<0.01) in all patients. P1 (r= -0.531, p<0.01) and N1 amplitude (r= -0.367, p=0.02) in the central ring of MF-ERG had a significant negative correlation with macular thickness in the corresponding foveal ring of SD-OCT in all patients.
MF-ERG showed significant reduction in amplitudes in each of the 5 rings in patients with NPDR with and without CSME, reflecting retinal dysfunction irrespective of the occurrence of CSME in patients with NPDR. Poorer BCVA correlates with reduced amplitudes and prolonged implicit times on MF-ERG, reinforcing that the MF-ERG can be an acceptable method of objectively assessing the macular function. Increased foveal thickness on SD-OCT also correlated with reduced amplitude in the corresponding ring on MF-ERG, thus the combination of SD-OCT and MF-ERG may thus provide may provide complete structural and functional information about the macula in diabetic retinopathy.