Colour vision tests Flashcards
Ishihara (24 plates edition) use
https://www.youtube.com/watch?v=hwGDOJyZJnk&list=PLnzCUQGYmvpLCrrO3sLPeSinwyDMkR2Ye
The instructions give the responses for those with normal CV, and those with defects.
This test is designed to detect those with red and green deficiencies or monochromatism.
Ishihara responses
Plates are held perpendicular to the line of sight at 75cms from the patient.
Responses should be stated within 3 seconds.
Ishihara method
The patient is asked to name the number as each plate is shown.
The first plate is a demonstration plate and the number will be seen by all.
The number of correct plates is recorded.
City Colour Vision test (3rd edition) method
https://www.youtube.com/watch?v=Y0zQreq0864&list=PLnzCUQGYmvpLCrrO3sLPeSinwyDMkR2Ye&index=2
Plates are held perpendicular to the line of sight at 35cms from the patient.
The patient is asked which of the 4 discs surrounding the central disc is most similar in colour.
City Colour Vision test (3rd edition) use
The instructions give the responses for each form of colour defect.
City Colour Vision test (3rd edition) results
The response given is recorded on the score sheet and the type of defect is identified from the top column where recorded responses fall.
D15 test
https://youtu.be/ysk4HLsWZ8M
You are asking the patient to put the ‘pots of colour’ in order.
At a distance of 50 cms the patient is instructed to place the caps of different shades sequentially in a gradually changing order from the first fixed cap.
D15 recording
The number on the back of each cap is recorded in the sequence the patient put them in. From this an error score is calculated, the higher the number of errors, the worse the colour defect. >70 usually equates to a defect.
City Colour Vision test (3rd edition) results
The first set of plates screen for a defect and the second set, with smaller diameter circles of colour, give more information on severity.
Distance for City test
35cm
How long should patients be given to state their response for each plate in the Ishihara test?
3 seconds
Which test only allows for the detection of protanopia and deuteranopia?
Ishihara
A congenital colour vision defect:
Is bilateral
Which condition is least likely to cause an acquired CV deficiency?
6th nerve palsy
Which term does not mean colour blindness?
Anomalous trichromacy
