[A web-based Colour Vision Test as a Tool for Qualitative Evaluation of Pseudoisochromatic Pflüger Trident Colour Plates].

BACKGROUND: Pseudoisochromatic colour plates are constructed according to specific principles. They can be very different in quality. To check the diagnostic quality, they have to be tested on a large number of subjects, but this procedure is can be tedious and expensive. Therefore, the use of a standardised web-based test is recommended.

METHODS: Eight Pflüger trident colour plates (including 1 demo plate) according to the Velhagen edition of 1980 were digitised and inserted into a web-based colour vision test (www.color-vision-test.info). After visual display calibration and 2 demonstrations of the demo plate (#1) to introduce the test procedure, 7 red-green colour plates (#3, 4, 10, 11, 12, 13, 16) were presented in a randomised order in 3 different randomised positions each for 10 seconds. The user had to specify the opening of the Pflüger trident by a mouse click or arrow keys.

RESULTS: 6360 evaluations of all plates from 2120 randomised subjects were included. Without error, the detection rates of the plates were between 72.2% (plate #3) and 90.7% (plate #16; n = 6360). With an error number of 7 errors per test, the detection rates of the plates were between 21.6% (plate #3) and 67.7% (plate #16; n = 1556). If an error number of 14 errors was used, the detection rates of the plates were between 10.9% (plate #11) and 40.1% (plate #16; n = 606). Plate #16 showed the highest detection rate - at zero error number as well as at the 7 and 14 error limit. The diagnostic quality of this plate was low. The colourimetric data were improved. The detection rate was then significantly lower.

CONCLUSIONS: The differences in quality of pseudoisochromatic Pflüger trident colour plates can be tested without great effort using a web-based test. Optimisation of a poor quality colour plate can then be carried out.