Define about the Ishihara's Plates of eyes

Ishihara's Plates: Following plates are available- Transformation, Vanishing, Hidden Digit and Diagnostic plates.

1) The plates are designed to be viewed correctly in a room that has an adequate amount of daylight. Direct sunlight or electric light may interfere with the results because of a change in the shades of colour.

 2) The plates are held 75 cm away from the subject and tilted so that the plane of the paper is at right angles to the line of vision.

 3) The plates should be read number-wise and each answer should be given without more than 3 seconds delay.

4) If the subject is unable to read numerals, plates 26-38 are used and the winding lines between the two X's are traced with the brush. Each tracing should be completed within 10 seconds- for illiterates.

5) The order of the plates may be changed if it appears that there is a deliberate deception on the part of the patient.