«National Vision and Hearing Screening Protocols Revised 2014 Citation: Ministry of Health. 2014. National Vision and Hearing Screening Protocols: ...»
Children over three years of age with visual acuity abnormalities could be referred either to • the ophthalmologist at a hospital eye clinic or to an optometrist.
Children failing a formal visual acuity screening Formal vision screening as part of the New Zealand Well Child/Tamariki Ora schedule is undertaken at four years of age as part of the B4School check and at 11 years of age. Vision screening for children aged 11 years has two possible outcomes; a pass or referral (a failure to meet the performance level considered acceptable on the occasion of the screening).
A child who is referred from the vision screening with a visual acuity of 6/12 or worse in either eye should receive further professional investigation.
National Vision and Hearing Screening Protocols Colour vision: Ishihara pseudoisochromatic plate Conditions Illuminate with indirect daylight (do not use in direct sun). The light level must be 500–600 lux. The plate must be held about 75 cm (30”) with the child’s line of sight perpendicular to the page (if the test is held at a normal reading distance the visibility of the numbers is reduced and the test is more difficult because the coloured dots making up the numbers are more obvious). Make sure that no other child can see the screening or overhear the responses of the child you are screening.
Equipment This screening uses the 24-plate edition of the Ishihara Test for Colour Deficiency. The Ishihara books must be replaced at least every seven years.
Procedure Explain that you will be flipping through the pages of the book and asking the child to either identify the number or numbers on each page or to let you know if there is no number (some pages have no numbers). Reassure the child that there is no ‘trick’. The order of the plates may be jumbled to eliminate learning effects.
Presentation Make sure the child can identify the number on plate one correctly. Vision must be better than 6/60 for this plate. Continue to present each of the test plates two through 17 (in the 24-plate edition), allowing approximately three seconds each plate and count the number of plates misread. Do not count as a fail if a child has self-corrected. Where a single plate has two numbers on it, an error on either one or both numbers counts as a single error. Note the number of failed plates.
Ishihara colour vision screen (Ishihara pseudoisochromatic plate) On the 24-plate edition if three or less errors are made, record as ‘Colour Vision: Pass’ on the child’s records. The word normal is not used, as this is a screening test result only and is not a full colour vision assessment by an optometrist.
On the 24-plate edition if more than three errors are made on the number plates (2 to 17) then a colour vision defect is almost certain to be present. Record as ‘Colour Vision: Defect’. The number of errors made on Ishihara is not a reliable estimate of the severity of any colour vision defect.
No referral is warranted, unless further diagnosis is required. The child and parents should be informed so they can discuss career options. Also if a colour vision defect is present then some educational methods, which use colour coding, can be compromised. There are no rescreen criteria for colour vision screening. A defect result warrants a notification to the parent.
Recording of Ishihara colour vision The results of this screen must be recorded in the Ministry of Education’s ENROL database.