Further observations on the extramacular chromatic mechanisms

Monochromatic targets presented at 30 degrees excentricity on orange, magenta and blue backgrouds are used. A small monochromatic light, 476 nm on orange, 551 nm on magenta and 621 nm on blue, is flashed at 3 cps-1 on the centre of the targets. The size of the targets is varied and their luminance adjusted using neutral filters until the flashing light is just not visible. This method allows the study of chromatic mechanism sensitivity and of retinal interactions (summation and inhibition). Some observations in normal as well as in pathological conditions are presented.