Assessing the impact of non-dilating the eye on full-field electroretinogram and standard flash response

We investigated the possibility of performing electroretinography (ERG) in non-pharmacologically dilated eyes using brighter flash (time-integrated) luminance. Photopic (N = 26; background 25.5 cd·m⁻², white LED flashes) and scotopic ERG (N = 23, green LED flashes) luminance response functions were obtained simultaneously in a dilated (DE) and non-dilated eye (NDE). In the NDE, photopic V _max b-wave amplitude was reduced by 14% (P < 0.0001), implicit time prolonged (P < 0.0001), and retinal sensitivity (log K) decreased by 0.38 log units (P < 0.0001) with no effect on a-wave. Using a xenon strobe light (N = 6) to increase flash luminance, V _max remained lower by about 12% in the NDE (P = 0.02). V _max with LED and xenon was achieved at 3.9 ± 1.0 cd·s·m⁻² and 3.3 ± 0.81 cd·s·m⁻² in the DE and 10.6 ± 1.2 cd·s·m⁻² and 12.3 ± 1.90 cd·s·m⁻² in the NDE, that is an increase of 0.43 and 0.57 log unit (P < 0.0001), respectively. Increasing background luminance by 0.50 log units (80 cd·m⁻², N = 4) resulted in implicit time normalization but not V _max amplitude. Rod V _max was decreased by 7% in NDE (P < 0.05) and sensitivity reduced by 0.40 log units (P < 0.0001), but our data suggest that the luminance may have not been sufficient to reach V _max in all participants in the NDE and that the sensitivity change may have been due to an inadequate inter-stimulus interval. For the photopic ERG, increasing flash luminance is not sufficient to compensate for the smaller pupil size, whereas for the scotopic ERG, more data are needed to establish proper inter-stimulus interval to perform recordings in a non-pharmacologically dilated.