Flicker cone electroretinogram in dichromats and trichromats.
To measure cone signal strengths in the flicker electroretinogram (ERG) of dichromats and trichromats, we developed a set of flickering stimuli (30 Hz), which excite the middle-wavelength-sensitive (M-) and long-wavelength-sensitive (L-) cones independently. ERG responses to eight different ratios of L- to M-cone contrasts were recorded from each subject. The short-wavelength-sensitive (S-) cone contrast was 0% in all measurements. The recordings were Fourier analyzed to determine the amplitude of the fundamental component. ERG threshold values for each subject resulted in ellipses when plotted in an L-/M-cone contrast space. As expected, the orientations of the threshold ellipses of the protanopes (N = 2) were parallel to the L-cone axis, whereas those of the deuteranopes (N = 2) were parallel to the M-cone axis. For the trichromats (N = 5), there was considerable interindividual variation in ellipse orientation.
Usui
T
T
Department of Experimental Ophthalmology, University Eye Hospital, Tübingen, Germany.
Kremers
J
J
Sharpe
L T
LT
Zrenner
E
E
D000328:Adult; D003117:Color Vision Defects / Q000503:physiopathology*; D015350:Contrast Sensitivity / Q000502:physiology; D004596:Electroretinography; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D011601:Psychophysics; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000502:physiology