Document Detail

Assessing the severity of color vision loss with implications for aviation and other occupational environments.
MedLine Citation:
PMID:  22272512     Owner:  NLM     Status:  In-Process    
INTRODUCTION: The Ishihara Test (IT) is arguably the most sensitive and commonly used color vision test within aviation and other occupational environments, but when no errors are allowed -20% of normal trichromats fail the test. The number of allowed errors varies in different occupations and sometimes within the same environment (such as aviation) in order to reflect the difficulties of the color-related tasks. The implicit assumption is that the plates can be ranked in order of difficulty. The principal aim of this study was to investigate whether appropriate "weights" can be attached to each IT plate to reflect the likelihood of producing a correct response. A second aim was to justify the use of color thresholds for quantifying the loss of red-green (RG) and yellow-blue (YB) chromatic sensitivity.
METHODS: We investigated 742 subjects (236 normals, 340 deutans, and 166 protans) using the first 25 plates of the 38-plate IT and measured RG chromatic sensitivity using the Color Assessment and Diagnosis (CAD) test. The IT error scores provided plate-specific "weights" which were used to calculate a Severity Index (SI) of color vision loss for each subject.
RESULTS: Error scores, SI values, and CAD thresholds were measured and compared in each of the three subject groups.
CONCLUSIONS: Color thresholds can provide a good measure of the severity of both RG and YB color vision loss. Neither the number of IT plates failed nor the SI value computed in this way can be used to determine reliably the severity of color vision loss.
Marisa Rodriguez-Carmona; Matilda O'Neill-Biba; John L Barbur
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  83     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  19-29     Citation Subset:  IM; S    
The Henry Wellcome Laboratories for Vision Sciences, Applied Vision Research Center, City University London, Northampton Square, London EC1V 0HB, UK.
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