Sunglasses, traffic signals, and color vision deficiencies.
OBJECTIVE
To determine (a) the effect of different sunglass tint colorations on traffic signal detection and recognition for color normal and color deficient observers, and (b) the adequacy of coloration requirements in current sunglass standards.


METHODS
Twenty color-normals and 49 color-deficient males performed a tracking task while wearing sunglasses of different colorations (clear, gray, green, yellow-green, yellow-brown, red-brown). At random intervals, simulated traffic light signals were presented against a white background at 5 degrees to the right or left and observers were instructed to identify signal color (red/yellow/green) by pressing a response button as quickly as possible; response times and response errors were recorded.


RESULTS
Signal color and sunglass tint had significant effects on response times and error rates (p < 0.05), with significant between-color group differences and interaction effects. Response times for color deficient people were considerably slower than color normals for both red and yellow signals for all sunglass tints, but for green signals they were only noticeably slower with the green and yellow-green lenses. For most of the color deficient groups, there were recognition errors for yellow signals combined with the yellow-green and green tints. In addition, deuteranopes had problems for red signals combined with red-brown and yellow-brown tints, and protanopes had problems for green signals combined with the green tint and for red signals combined with the red-brown tint.


CONCLUSIONS
Many sunglass tints currently permitted for drivers and riders cause a measurable decrement in the ability of color deficient observers to detect and recognize traffic signals. In general, combinations of signals and sunglasses of similar colors are of particular concern. This is prima facie evidence of a risk in the use of these tints for driving and cautions against the relaxation of coloration limits in sunglasses beyond those represented in the study.
Dain
Stephen J
SJ
FAAO School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia.
Wood
Joanne M
JM
Atchison
David A
DA
D000063:Accidents, Traffic / Q000517:prevention & control*; D000293:Adolescent; D000328:Adult; D003116:Color; D003117:Color Vision Defects / Q000503:physiopathology*; D005135:Eye Protective Devices; D005139:Eyeglasses; D006801:Humans; D008297:Male; D011930:Reaction Time; D013472:Sunlight; D014186:Transportation / Q000295:instrumentation*; D055815:Young Adult