Optical Properties of the Retinal Receptors*†

Abstract

In the study of receptor optics, the current era originates with the discovery of retinal directional sensitivity by Stiles and Crawford in 1933. In recent years the essential complexities of receptor-optical properties have been revealed.These properties give rise to directional sensitivity, hue, saturation, and resolution changes. They have been employed to separate photopic from scotopic functions, and to indicate the status of receptor-orientation properties. In some patients exhibiting amblyopia or retinal pathology, characteristic disturbances in receptor directional sensitivity have been noted. It is now possible to induce changes in human receptor orientation.Retinal receptors, mitochondria in receptor ellipsoids, and the lamellae and the photosensitive pigment in each lamella of receptor outer segments are orientated. Taper of ellipsoids in retinal cones allows more efficient energy transfer and probably plays an important role in receptor directionality. The configurations, diameters, and indexes of the receptors give rise to the waveguide modal-pattern form of energy transfer. This results in nonuniform distributions of energy in and about receptor outer segments. These distributions and their transmissivity vary within single, and between different retinal receptors as a function of wavelength, and angle of incidence of light. The roles played by these phenomena in vision (particularly the wavelength separation mechanism) require evaluation.