GUIDANCE ON OCCUPATIONAL COLOUR VISION TESTING.
Where there is an occupational need for the testing of colour vision, members are advised to ensure that the patient is not wearing a colour-enhancing appliance, such as X-Chrom or Chromagen lenses. In some instances it may be difficult to differentiate such lenses from other, “cosmetic”, tints being worn either as spectacles or contact lenses. Most occupational requirements do not permit the use of such lenses to enable the candidate to pass a colour vision test. If a colour vision test was “passed” with the use of such an appliance, the optometrist should note this on the report form.
Lantern Tests
In many places, standards require a Holmes-Wright or Giles-Archer lantern test for colour vision. Neither of these devices have been manufactured for many years and very few still remain in working order. The CAM (Clinical Aviation Marine) Lantern test represents a modern alternative to these tests and has been calibrated to give similar results. The CAM lantern may be used in place of the above lanterns where appropriate. The CAM lantern is manufactured by Evans Instruments Ltd and comes with instructions to simulate the results of the older lantern tests: http://www.evansinstruments.co.uk/
Please see the pdf articles at the end of this page for further information.
