Abstract
Purpose :
PhNR is the negative potential that follows the b wave of full field Electroretinogram(ffERG). It is affected in ganglion cell disorders. Its role in early detection of diabetic retinopathy(DR) is not widely studied especially using monochromatic stimulus. The aim of this study was to study both broadband (white on white) and monochromatic (red on blue and blue on yellow) stimulus PhNR in ffERG in diabetic eyes without DR and with different stages of DR
Methods :
In a prospective, non-randomized, case control study, 50 controls and and 52 treatment naïve diabetic eyes (6 eyes without DR, 8 eyes with mild nonproliferative diabetic retinopathy (NPDR), 11 eyes with moderate NPDR, 9 with severe NPDR and 18 eyes with proliferative diabetic retinopathy (PDR) of 26 patients were included in the study. Eyes with refractive error more than +/-5.00D or any retinal pathology or glaucoma were excluded.Color fundus photography and comprehensive ophthalmic examination was done and stages of DR were defined according to International Diabetic Retinopathy Disease Severity Scale. Standard ffERG was recorded with Burian Allen electrodes using the VERIS 6.4.4. system. Broadband PhNR was recorded using white stimulus on white background (w/w) and monochromatic PhNR was elicited in two ways a) with red stimulus on blue background (r/b) and blue stimulus on yellow background (b/y).
Results :
As compared to controls the mean amplitudes of a-wave (67.28+/-12.88 vs 40.68+11.79), b-wave (134.39+/-28.78 vs 118.35+/-47.37), w/w PhNR (67.18+/-15.99 vs 31.90+/-16.06), r/b PhNR(53.48+/-14.15 vs 29.93+16.45) and b/y PhNR (104.79 +/- 24.37 vs 46.53+/-24.51) were significantly reduced (p=<0.05) in diabetic eyes. Significant decrease in amplitudes of a-wave,w/w PhNR and b/y PhNR was seen in all categories of DR, significant decrease in amplitudes of b-wave was seen in severe NPDR and PDR; significant decrease in r/b PhNR was seen in moderate, severe NPDR and PDR. Percentage reduction in amplitudes of w/w PhNR( 62%) and b/y PhNR(62%) was more as compared to a wave(42%) and b wave (10%) even in patients with no DR.
Conclusions :
Changes in ERG reflect severity of DR. W/w and b/y PhNR amplitude are reduced in DR patients even in the absence of visible changes in the retina. Further studies in larger population are necessary to evaluate the role of PhNR waves in diabetic eyes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.