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PURPOSE To screen for acquired or hereditary color vision defects．These clinical screening tests are particularly significant for the assessment of macular cone and optic nerve function．
EQUIPMENT
·0ccluder．
·Lamp of the correct color temperature for the particular test book used．
·Test book containing pseudoisochromatic plates(PIPs)or other material．
SET-UP
·The patient wears his habitual correction for near．
·The patient holds the occluder．
·The examiner holds the test book 50 cm from the patient．
STEP-BY-STEP PROCEDURE
1．Instruct the patient to occlude his left eye to test his right eye．
2．0bserve the patient to make sure that only one eye can see the test plates．
3．Turn the pages one at a time，asking the patient to identify the number or figure on each page．
4．Instruct the patient to occlude his right eye．
5．Repeat steps 2 and 3 to test the left eye．
RECORDING
·For each eye write the number of correctly identified plates，a slash mark, and then the number of plates tested(ie，a fraction)．Remember that the first plate in many PIP booklets is for demonstration purposes and does not actually test the patient’s ability to see color．Therefore，it should not be counted when recording the number of plates tested．
·Record the type of test used．
EXAMPLES
·Color：OD 12/13 OS 11/13 Ishihara
·Color：OD 13/14 OS 8/14 AO
EXPECTED FINDINGS
Each pseudoisochromatic plate test booklet comes with instructions．These should be read to ascertain what is considered normal for that particular test．In some tests it is normal to make as many as 4 mistakes out of 13 pseudoisochromatic plates tested． |
