The studies identified for critical appraisal had limitations that should be considered when interpreting the following conclusions:
There were no adequate treatment options for the correction of impaired colour vision on current evidence.
Of the approximately 7% of the male population with congenitally impaired colour vision approximately 40% of that population appears to be unaware of the defect prior to leaving secondary school.
It was not possible to identify the impact colour vision screening has on reducing educational and occupational difficulties or motor vehicle crash rates.
There was insufficient evidence to either agree or disagree with the hypothesis that those with impaired colour vision have more road traffic crashes.
Further research was required to assess the role impaired colour vision has on educational attainment.
Those involved in air traffic control and sea search and rescue operations should have normal colour vision. Research on other occupations, which normally restrict those with impaired colour vision, was not identified in this report but it should not be assumed that such restrictions are unnecessary.
There was insufficient evidence for the use of colour vision screening as a method of first detection of an adverse health outcome other than impaired colour vision.
There was currently insufficient evidence to recommend a change in the colour vision screening test currently in use within New Zealand (Ishihara's pseudoisochromatic test) on the basis of its validity.
Cost-effectiveness information is needed to compare the costs of the various screening tests against sensitivity and specificity criteria.
It was not possible to evaluate the effectiveness of a colour vision screening programme on the basis of current research. This was identified as an area requiring further research, incorporating a randomised controlled trial as the most appropriate research design for this purpose.
