Color vision assessment: fail rates of two versions of the Farnsworth lantern test.
BACKGROUND
The Farnsworth lantern test has long been used to assess the color vision of those seeking to enter the aviation industry and other occupations that require recognition of signal lights. A new version of the Farnsworth lantern, the Optec 900, is now produced because the original version is no longer manufactured. This paper reports the pass/ fail rates of a production model of the new version compared with an original one.


METHODS
There were 100 male subjects with abnormal color vision who were given 3 runs with each lantern test. Their color vision deficiency was diagnosed using a battery of tests including the D15 test and the Nagel anomaloscope.


RESULTS
A total of 19% passed the new lantern test compared with 24% for the original Farnsworth using the usual fail criteria. The pass rates become 17% and 21%, respectively, when adjusted for the expected proportions of the types of abnormal color vision. There was agreement between the two lantern tests for 89% of subjects: 8% passed the old Farnsworth and failed the new version, and 3% failed the original Farnsworth and passed the new. There was a practice effect: when one lantern was passed and the other failed, the lantern passed was, with one exception, given second. Both lantern tests passed subjects who made no errors on the first run who subsequently made many errors when given further runs. Only 4% of subjects made no errors on all runs.


CONCLUSIONS
The Optec 900 can be considered equivalent to the Farnsworth lantern and might be preferred because it is slightly more stringent, reducing the risk of passing those who will make errors with signal lights. The practice of passing applicants who make no errors on the first run should be abandoned since 10% of those who pass in this way make many errors when additional runs are given.
Cole
Barry L
BL
Department of Optometry and Vision Sciences, University of Melbourne, Victoria, Australia. bcole@optometry.unimelb.edu.au
Lian
Ka-Yee
KY
Lakkis
Carol
C
D000293:Adolescent; D000328:Adult; D000337:Aerospace Medicine; D016009:Chi-Square Distribution; D002648:Child; D003119:Color Perception Tests / Q000379:methods*; D003117:Color Vision Defects / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric