Selective loss of sensitivity to blue and green parts of the spectrum following intermit-tent, repeated exposures to intense spectral lights persists longer than three years following blue lights and between 18 and 40 days following green lights. The "blue-blindness" involves complete and sole loss of the response of the short-wavelength responsive cones. The "green-blindness" complete and sole loss of response of middle-wavelength sensitive cones. Histo-pathology of cones in a "blue-blinded" retina in comparison with cytochemical labeling of short-wavelength cones, reveals that they follow a similar distribution: are sparse in the foveola, reach a peak of about 16 percent of the cones near 1° and fall to 8-12 percent of the cones at 7°. Continuous as distinct from intermittent exposures to similar blue lights produces a wholly different pricture of gross pigment-epithelial damage with little photoreceptor degeneration.