Analysis of the Mark II edition of The City University Colour Vision Test

The City University (TCU) test was administered to 50 dichromats and 56 anomalous trichromats. Certain poorly performing plates are identified from the accuracy of diagnosis compared with the Nagel anomaloscope and the number of dichromats passing the plates. Some plates are indicated as providing a more reliable diagnosis, particularly when used in combination. The performance of the plates is compared with their colorimetric properties. The desaturated plates, which were not part of the Mark I test, are shown not to provide the intended extent diagnosis.