Ishihara’s Colour Blindness Book 24 Plate
The Ishihara test 24 plates consists of a number of coloured plates, each of which contains a circle of dots appearing randomized in color and size. Within the pattern are dots which make a number or shape visible to those with standard colour vision, and invisible, or difficult to see, to those with a red-green colour vision defect, or the other way around. The full test has up to 38 plates, but the existence of a deficiency is usually clear after a few plates. There is also the smaller test consisting only 14 plates.
The Ishihara test 24 plates is aimed at patients with Deuteranomaly, Protanomaly, Protanopia and deuteranopia, Tritanomaly, and Tritanopia.
The Ishihara test 24 plates consists of a number of coloured plates, called Ishihara plates, each of which contains a circle of dots appearing randomised in colour and size. There are also Ishihara colour tests consisting of 10, 14 or 24 test plates, and plates in some versions ask the viewer to trace a line rather than read a number.
Transformation plates: individuals with color vision defect should see a different figure from individuals with normal color vision.
Vanishing plates: only individuals with normal color vision could recognize the figure.
Hidden digit plates: only individuals with colour vision defect could recognize the figure.
Diagnostic plates: intended to determine the type of colour vision defect (protanopia or deuteranopia) and the severity of it.
Classification design: This is used to differentiate between red- and green- blindness. The vanishing design is used on either side of the plate — one side for debutant defects and the other for protans.