Visual pigments of rods and cones in a human retina.

Abstract

Microspectrophotometric measurements were made of the photopigments of individual rods and cones from the retina of a man. The measuring beam was passed transversely through the isolated outer segments. The mean absorbance spectrum for rods (n = 11) had a peak at 497.6 .+-. 3.3 nm. The mean transverse absorbance was 0.035 .+-. 0.007. Three classes of cones were identified. The long-wave cones (red cones) had a .lambda.max of 562.8 .+-. 4.7 nm (n = 19) with a mean transverse absorbance of 0.027 .+-. 0.005. The middle-wave cones (green cones) had a .lambda.max of 533.8 .+-. 3.7 nm (n = 11) with a mean transverse absorbance of 0.032 .+-. 0.007. The short-wave cones (blue cones) had a .lambda.max of 420.3 .+-. 4.7 nm (n = 3) with a mean transverse absorbance of 0.037 .+-. 0.011. If assumptions are made about the length of cones and pre-receptoral absorption, it is possible to derive psychophysical sensitivities for the cones closely resembling the appropriate .pi. mechanisms of W.S. Stiles. If assumptions are made about the length of rods and about pre-receptoral absorption, the psychophysical sensitivity derived for the rods is considerably broader than the C.I.E. [International Commission of Illumination] scotopic sensitivity function.