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Retinal adaptation of II infants and children with progressive retinal degenerations was studied. Diagnostic categories were Leber's congenital amaurosis (4 patients), infantile ceroid lipofuscinosis (1 patient), and retinitis pigmentosa syndromes (6 patients). Only limited appraisal of function was done electrophysiologically because all patients had extinguished or much attenuated electroretinal responses. Pupillography and psychophysical procedures did allow assessment of dark adapted sensitivity, and adaptation to steady background lights and after exposure to bleaching lights. From infancy onward, patients with these disorders had elevated dark adapted thresholds. Temporal integration appeared to be normal in patients with the RP syndromes and in a patient with Leber's congenital amaurosis. Steady background lights decreased retinal sensitivity, but less in patients than normal controls. The recovery from bleaches was abnormal in some patients. These preliminary results describe abnormal retinal adap...

Various lighting and video display terminal design recommendations have been based on the assumption that the eye adapts to the average luminance of the field being viewed. Other evidence suggests that for irregular patterns the eye adapts to a level biased toward the peak luminance in the field being viewed. Subjects in this study adapted to uniform fields of varying average luminance and to two test patterns, one of which (dots) had a peak luminance equal to the brightest uniform field and an average luminance equal to the least bright uniform field. Time, to respond to a test pattern following adaptation to dots was intermediate between the two extreme uniform fields, but closer to that of the brighter field which had an average luminance equal to the test pattern's peak luminance. For that reason, proposed lighting differences based on image polarity or recommendations of positive image polarity do not appear to be warranted.

An image which is stabilised with respect to the retina functionally eliminates the micronystagmoid movements of the eyeball. The degree of elimination depends on the accuracy of stabilisation achieved. A variety of apparatus has been used to try and achieve accurate stabilisation but at the same time to provide a method which permits the use of a wide range of material to act as the stabilised target. The stabilised image has been studied with various types of images and under various conditions of viewing. The fading of the stabilised image is comparable with Troxler's Effect. The comparative study of these two phenomena leads to some interesting conclusions. An attempt has been made to relate the fading of the stabilised image to Troxler's Effect and to understand the fading process in terms of retinal adaptation, eye movements, and the part played by higher centres in the visual pathway. As well as throwing light on the function of the eye movements, the study of the stabilised retinal image has been used in the field of psychology to investigate figural after-effects, geometrical illusions, and theories of perception.