This comprehensive. up• to-date account of vision in the pigeon begins with a description of the eye, its dimensions, and optical properties. The retina is discussed in considerable detail, with particular attention given to: the distribution of the various cell types within and across the retina, the number and the nature of the oil drops in the cones, the highly developed inner plexiform layer, the response characteristics of the ganglion cells, and the damage to cones caused by exposure to light. Lastly, the three major visual pathways are examined neuroanatomica11y and electrophysiologica11y. In the second section, several important issues have been emphasized: the putative differences between frontal and lateral vision, visual sensitivity to both discrete and periodic stimuli at various adaptation levels, polarotaxis in the pigeon, the bipartite spectral sensitivity of its retina, hue and saturation discrimination, sensitivity to ultraviolet light, panoramic acuity, and the detection of movement.

No abstract

This report represents a preliminary attempt to characterise photoaversion in RP, which we define as symptomatic interference with visual performance due to exposure to bright light. RP patients were surveyed to discover the frequency and nature of complaints, and presented with a variety of psychophysical tests to define and quantify the symptom of 'photoaversion'. Material and methodsA total of 20 photoaversive RP patients (11 male, 9 female) performed psychophysical tests (though no subject performed all tests). The age range was 11-68 (average 34); visual acuity ranged from 20/20 to 20/70. RP was documented by history, fundus examination, ring scotoma, and electroretinography; no patients had more than a trace of posterior