Devices that have been developed for checking night vision are reviewed. The particular apparatus developed by allgaier is described. The reliabilities of two aspects of the night sight meter scores are presented in a table. Using the scotometer and the night sight meter, the subject is placed at the eyepiece with a black hood over the head to secure adaptation while directions for the experiment are being read. The subject looks into the scope of the night sight meter and fixates a red pilot light of very low intensity. Just to the left of the pilot light is a rotating disk on which are presented broken circles at a constant rate of speed moving past an aperture. The procedure is varied slightly for the test of glare tolerance. The time required for recovery from glare in terms of seconds is measured. A reliable criterion of night visibility was established by the use of the scotometer using 39 subjects. After this the night sight meter was used on 34 additional subjects to establish correlations and the validity of the instrument. It is concluded that the validity of the meter is sufficient to warrant its use as a diagnostic instrument, but that the administration time should be reduced.
Abstract