A lantern color vision test for the rail industry.
BACKGROUND
Correct identification of wayside signal colors is critical for safe operation of railway equipment. However, evaluating color discrimination using just a screening test may not be occupationally relevant.


METHODS
A lantern test (CNLAN) was designed to provide a functional assessment of color discrimination for the rail industry. It was validated against a simulated field trial. 81 individuals with normal color vision and 74 individuals with congenital red-green defects participated. Color vision was classified using the Nagel Anomaloscope.


RESULTS
Using a criterion based on the worst-normal performance, 97% of the individuals with a color vision defect failed both the CNLAN and simulation trial. This value is slightly lower than the 100% who failed both the Ishihara test and simulation. However, the Ishihara test also failed 3.7% of the color-normals who passed both the simulation and lantern, whereas by definition none of the color-normals failed the lantern.


CONCLUSIONS
This lantern test provides a reasonable functional assessment of one's ability to identify rail signal colors; especially when a strict failing criterion is applied to screening tests.
Hovis
J K
JK
School of Optometry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. jhovis@uwaterloo.ca
Oliphant
D
D
D000062:Accidents, Occupational / Q000517:prevention & control; D000328:Adult; D003117:Color Vision Defects / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D016272:Occupational Health; D011890:Railroads