RECOVERY OF SPATIAL VISION DURING DARK-ADAPTATION IN NORMAL SUBJECTS

We show, how sensitivity to sinusoidally-modulated gratings changes th roughout the course of dark adaptation. The luminance required to reso lve the bars of a variety of sinusoidal gratings of (0.6-14 c.p.d.) pr esented in the parafovea, was determined for 30 min following a full b leach, Data obtained for low and intermediate spatial frequencies (0.6 and 3.5 c.p.d.) was qualitatively similar to the classical dark adapt ation function, showing discrete cone and rod phases. Threshold to a 1 4 c.p.d. grating fell initially, then after approximately 10 min, rose by between 0.40 and 1.17 log units. This effect was not apparent for the 8.3 c.p.d. grating, despite the fact that both spatial frequencies must have been detected by cones. The phenomenon has been attributed to rod-suppression of cone-mediated vision. Copyright (C) 1997 The Col lege of Optometrists. Published by Elsevier Science Ltd.