Abstract
Purpose: :
In this study we were interested in characterizing L- and M-cone ERG responses from the human retina in response to cone isolating pulsed stimuli.
Methods: :
L- and M-cone specific ERGs were elicited using transient square wave pulse stimuli (onset = 100ms; offset = 150 ms) which were were equated in terms of cone modulation (0.11 cone contrast). Retinal illuminance was 12,000 trolands. These stimuli constituted triple silent substitutions which were generated on a 4 primary LED ganzfeld stimulator (Diagnosys ColorDome). Responses were recorded from 6 trichromats using DTL fibre electrodes.
Results: :
Responses to the onset of an L-cone isolating stimuli generated ERGs with a characteristic a- (latency = 20 ms) and b-wave (latency = 40 ms), followed by a clear offset response. ERGs to the onset and offset of M-cone isolating stimuli appeared to be reversed. M-cone stimulus offset generated a response with a- and b-waves similar to that elicited by the L-cone onset stimulus, whilst the onset of the M-cone stimulus elicited a response similar to the L-cone offset.
Conclusions: :
Our result demonstrates that L- and M-cone specific ERGs can be recorded from the human retina in response to transient on-off pulse stimulation. In the normal trichromats the ERG responses to L- and M-cone stimuli are suggestive of a post-receptoral origin for these responses similar to that of the cone opponent retino-geniculate pathway.
Keywords: electroretinography: non-clinical • color vision • retina: distal (photoreceptors, horizontal cells, bipolar cells)