Colour vision and NDT
14/03/2013
It has been recognised that NDT staff have a need for a measure of colour vision perception that is linked to the NDT method being applied. For many years there was no potential cure or corrective action available for those people who have colour vision deficiencies, typically 10% of the male population. ISO 9712: 2012 states: ‘b) colour vision shall be sufficient that the candidate can distinguish and differentiate contrast between the colours or shades of grey used in the NDT method concerned, as specified by the employer’.PCN has produced a document, PSL/44, to give general guidance and to record the results of a basic near vision and colour vision test using the Ishihara Colour Test. Where candidates are demonstrating a weakness in near vision, a trip to the optician or similar would usually result in the purchase of glasses, contact lenses or even corrective surgery but, for those candidates who demonstrate difficulties with their colour vision, there has been no corrective action available… until now.
It has been recently reported[1] that evolutionary neurobiologist Mark Changizi and colleagues have, by accident, developed in their American research a new type of lens that diminishes red-green deficiency but hinders the perception of yellows and blues. Glasses with ‘Oxy-Iso’ lenses are currently on sale at $279 (£178) and may help candidates with a colour vision deficiency. Researchers are also said to be developing interior lighting utilising so-called ‘O2Amp’ technology and are looking at an O2Lamp, which will filter the light itself, removing the need for eyewear.
Further investigation needs to be carried out into both the Oxy-Iso lenses and the O2Lamp and their usefulness in NDT, but it appears that there may be some potential advantages for those with colour vision deficiencies.
[1] Sources: The Times, Thursday 7 February 2013
Scientific American – ‘The Ravenous Color-Blind: New Developments For Color-Deficients (on-line, note American spellings).
See also ‘On what the eye can see – Part 2. Colour perception’, by Con Murren, NDT News, June 2011.
