Spatial Resolution Thresholds during the Course of Dark Adaptation: An Evaluation of the Recovery of Visual Function Following Failure of Optical Image Intensifiers

摘要

Recovery time to detect sine-wave gratings at five different contrast levels ranging from 10% to 75% contrast was measured at three average target luminance levels corresponding to three night viewing conditions. Five young adult subjects were used in the study. The recovery time was measured after the subject was preadaplated to three simulated optical image intensifier luminance levels. The average recovery time over five subjects was found to be linearly proportional to the log contrast for all frequencies and luminance levels used. The spatial contrast sensitivity functions expressed in terms of recovery time demonstrate distinct changes in contrast sensitivity with different adaptation luminances as well as target luminances. From these spatial contrast sensitivity function curves, one can predict very clearly the cut-off frequency i.e., the ability to discriminate fine structure at different viewing conditions. (Author)