A systematic review including 27 studies evaluating the validity of various colour vision screening tests was abstracted in DARE. The sensitivity of Ishihara's test (against anomaloscopy) ranged between 94% and 98%. In one study that evaluated the repeatability of Ishihara's test, good retest reliability was found. In no study was there evidence that Ishihara's test was less valid than any other screening test.
Comment: The quality of evidence is upgraded by large magnitude of effect.