Stiles–Crawford effect of the first kind: assessment of photoreceptor alignments following dark patching

• Published in: Vision research (Oxford) 2001, Vol.41 (1), p.103-118
• Main Authors: Kono, Momoyo, Enoch, Jay M, Strada, Elisabetta, Shih, Paul, Srinivasan, Ranjani, Lakshminarayanan, Vasudevan, Susilasate, Wilbur, Graham, Andrew
• Format: Article
• Language: English
• Subjects: Adaptation, Ocular - physiology; Adult; Biological and medical sciences; Effect(s) of dark patching; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Mathematical Computing; Orientation - physiology; Photoreceptor alignment (inferred); Photoreceptor Cells, Vertebrate - physiology; Retina; Stiles–Crawford effect of the first kind (directional sensitivity of the retina); Vertebrates: nervous system and sense organs
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/S0042-6989(00)00228-5

Properties of presumed mechanisms controlling photoreceptor alignments are partially defined. A phototropic mechanism normally dominates alignment, but do modest changes in orientations occur with dark patching? Here, new photopic Stiles–Crawford (SCE-I) determinations were made before patching (pre-patch), just after 8-days of dark-patching (post-patch), and 3 days after patch removal (recovery test). We tested at 0, 11 and 22° in the temporal retina of both eyes. Ten eyes of adult subjects were tested. SCE-I peak positions and Stile's parameter ‘rho’ were assessed. Dark-patching effects were small. Observations revealed meaningful corrective alignment overshoots with recovery in the light. Results suggest (1) the presence of multiple weak mechanisms affecting receptor alignments in the dark; (2) the phototropic mechanism to be dominant in the light; (3) the need for multiple test loci to be sampled in such studies, and (4) small changes in the SCE-I in the pupil plane can reflect meaningful events occurring at the retina.