Abstract
Purpose :
The b-wave and the Photopic Negative Response (PhNR) of the cone-mediated electroretinogram (cone ERG) are thought to reflect the activity of distinct generators in the post-receptoral retina, i.e. the retinal bipolar and ganglion cells, respectively. In some optic nerve disorders including glaucoma, these components can be selectively altered, being the PhNR virtually absent while the b-wave unaltered. The aim of this study was to investigate the relative involvement of b-wave and PhNR in mild NonProliferative diabetic retinopathy (mNPDR)
Methods :
Thirty-two patients (17 males and 15 females, age range: 52-76 years) with type 2 diabetes and mild NPDR as well as 18 age and sex matched controls were tested. Cone-mediated ERGs were recorded, according to a published protocol (Abed et al., 2017), in response to white 2 cd/m2 flashes presented on a 20cd/m2 adapting white background. Amplitudes and implicit times of the b-wave and PhNR, as well as the PhNR/b-wave amplitude ratio were measured
Results :
Compared to controls, mild NPDR patients showed on average significant losses (p < 0.01) of both PhNR and b-wave amplitudes, by 40 and 50% respectively. Both components were also delayed (p < 0.01) on average compared to normal values, by 10 and 6 msec, respectively. At least one of the two components was altered (in amplitude and/or implicit time) in 24 out of 32 patients (75%). The PhNR/b-wave amplitude ratio did not differ between patients and controls.
Conclusions :
The b-wave and the PhNR of the cone ERGs are similarly affected by NPDR, and can both be considered, in the clinical practice, as sensitive assays of post-receptoral retinal dysfunction.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.