Comparison of the Standard Pseudoisochromatic Plates to the Ishihara color vision test

The Standard Pseudoisochromatic Plates (SPP) color vision test was compared to the Ishihara color vision test with respect to screening validity, digit confusion errors, and individual plate efficiency. Results from 315 1st and 3rd grade males confirmed previous reports that the SPP is an effective screening test. Moreover, the SPP test was superior to the Ishihara test with respect to digit confusion errors. Color normal children made about 5 to 7 times as many errors on the Ishihara test as on the SPP. Screening inefficiency values of individual plates of both tests were calculated. A high inefficiency value of a SPP plate was usually caused by its inability to detect color defective subjects.