The electroretinogram evoked by the excitation of human foveal cones

Abstract

2. The action spectrum of the response obtained in this way agrees reasonably well with the observer's psychophysical foveal luminosity curve.3. For the peripheral retina, the action spectrum is similar to that of the fovea when allowance is made for differences in screening macular pigment.4. Such responses diminish when the test stimulus is focused on to the peripheral retina and disappear when the test light is focused on the blind spot.5. Therefore, the response to the test light fixated centrally is the result of the excitation only of cones mainly, if not exclusively, in the fovea.6. When the intensity of the background is reduced by a factor of 10, the action spectrum shows evidence of the effect of excitation of rods in the blue part of the spectrum and of cones in the red. These red and blue responses add linearly when combined together, provided they are adjusted to coincide in phase.

The human focal electroretinogram as a function of stimulus area

“…This is because the macular ERG reflects the foveal cone activity [1,2] and may correlate with important visual functions such as visual acuity [3,4], color vision [5] and flicker sensitivity [6].…”

Local ERG for clinical examination of eye diseases

“…It is also well known that the response vs intensity curve for the ERG is well approximated by the hyberbolic function v = Vmax * I /(I + o (1) where a is the semisaturating intensity and represents the stimulus intensity necessary to obtain one-half the maximal amplitude. If we assume that the stimulated retinal area (Sr) is illuminated uniformly with the intensity (I), then the remaining part of the retina outside of Sr will be illuminated with the scattered light of intensity:…”

“…The prospects of using a local macular ERG (L-ERG) clinically have been noted since 1962 [1][2][3][4][5][6][7][8][9][10][11]. However, no standard technique for recording a macular ERG has been available until recently (10)(11)(12)(13)(14).…”

Analysis of the electroretinogram in toxoplasma retinochorioiditis

“…the whole retina. Many authors have studied the possibility of stimulation of a localised area [22][23][24][25][26][27][28] with variable success. Obviously, localised stimulation is not possible in patients with dense vitreous clouding.…”