Citation

Lauer AR. Highw. Res. Board bull. 1951; 43: 45-51.

Copyright

(Copyright © 1951, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

A study was made of 20 filters, representing as many specific wave bands throughout the visible spectrum, to determine the relationship between the filter-transmission factor and visual acuity in low illumination with the test object viewed through the filter. Fifteen sets of measurements were made of visual acuity under normal conditions, and fifteen were made with opposing light or glare source, for a total of 600 separate observations. The study concludes that there seems no indication that filters before the eyes can in any way aid vision at low levels of illumination. Any media introduced between the eye and a stimulus object or situation on a roadway as a means of reducing glare is not to be recommended for night-time or any other condition which lowers acuity when maximum visual efficiency is desired.