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.
The Stiles-Crawford effect of the first kind (SCE-I) was measured on both emmetropic and myopic subjects at six different retinal locations. The results revealed a number of significant discrepancies in receptor alignment between the groups of different refractive errors. In myopic subjects, the receptors in the nasal retina (i.e. between the fovea and the optic nerve head) were found to be aligned nasally towards the optic nerve head, whereas the receptors in the temporal retina were aligned towards the centre of the exit pupil. In emmetropic subjects, the receptors across the retina were finely tuned towards the centre of the exit pupil. The magnitude of the receptor displacement in myopic subjects was found to be directly associated with the length of the eyeball.
To my wife and parents without whose loyalty, encouragement and affection, past, present and future achievement could not have been contemplated* To Dr. Glenn Fry, my graduate adviser, for the untold hours of guidance, and sincere advice, and the many helpful hints and ideas, which have made my graduate training and dissertation so rich and rewarding* To ray subjects,
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