title: A Modified Protocol for Color Vision Screening Using Ishihara.
abstract: BACKGROUND
  The Ishihara plates are commonly used as an initial occupational screening test for color vision. While effective at detecting red-green deficiencies, the color deficient subject can learn the test using different techniques. Some medical standards such as the European Aviation Safety Agency (EASA) require plate randomization and apply a stricter pass/fail requirement than suggested by Ishihara. This has been reported to increase the false positive rate up to ∼50%.
  
  
  METHODS
  Two modifications to the Ishihara protocol are investigated. These involved allowing subjects a second attempt where one or two reading errors were made and the presentation of rotated Ishihara plates.
  
  
  RESULTS
  A reduction of false positive rate to 5.9% was found. Correct identification of certain rotated Ishihara plates was not affected.
  
  
  CONCLUSIONS
  By using a modified Ishihara protocol, fewer color normal subjects would require unnecessary advanced color vision examination. Further, additional safeguards would be in place to ensure that no subject with a color vision deficiency could pass the Ishihara test.
authors.affiliation: UK Civil Aviation Authority, West Sussex, UK.
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Chorley
mesh_terms: D003119:Color Perception Tests / Q000295:instrumentation / Q000379:methods*; D003117:Color Vision Defects / Q000175:diagnosis*; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans