1:30min
Professor Anthony Adams (L) and Dr David Cockburn
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Patrick Hutchens
Anthony Adams did not discover that he had a mild colour vision defect until he began studying at the University of Melbourne.
The fact that he built a career in optometry that included research into the field of colour vision shows that his condition was not a barrier to accomplishment. He is Professor Emeritus of optometry and vision science at University of California.
Retired optometrist Dr David Cockburn learned of his deuteranomaly during the Second World War while training to become an industrial chemist. The area of work he struggled with was the same as that which Terry Blake, a semi-retired optometrist from Melbourne, stumbled on in high school chemistry—titration in chemical analysis.
For both, it would be the trigger for learning they had a colour vision deficiency. This would steer them to learn adaptive behaviours while studying optometry, ensuring their clinical practice remained unaffected.
Senior lecturer in the department of optometry and vision sciences at University of Melbourne, Anthea Cochrane, says they usually have one or two students in each year of their optometry course who have a colour vision defect. A few are studying in the current cohort, across different levels.
If one of the students isn’t aware of their colour deficiency on arrival at the school, they are before the end of their first year, after students perform the Ishihara test on one another.
Ms Cochrane says there are strategies that students can use in their pre-clinic work to help with their colour vision defect.
‘One of the most important things is that the student is first aware how this may impact on their examination of a patient. We discuss and suggest how they may adapt and supplement their examination techniques. For example, red free filters are encouraged to supplement direct and indirect ophthalmoscopy,’ she said.
Felix Tam, a third-year Doctor of Optometry student at University of Melbourne, was diagnosed last year by his clinical supervisors with severe protanopia. When he was 18, his local optometrist showed Mr Tam the Ishihara test and told him that he had a red/green colour deficiency.
‘He couldn’t tell me specifically if it was red or green deficiency and I felt a little let down because the feeling I got at the end of the consultation was that there was nothing I could do about it,’ he said.
Since he entered optometry school, Mr Tam has conducted colour vision screenings on his colleagues. ‘I tried to learn how to better decipher colours in the Ishihara test—with little success,’ he said.
Mr Tam faces challenges when examining a patient’s posterior eye health under the yellow slitlamp light, especially in dim light or when he has only a little time to try to analyse the colour.
Acquired
Someone may not know that they have colour vision deficiency because they may have acquired it. Professor Adams recalls teaching an optometry student who, during the course of becoming familiar with colour vision tests in a laboratory with other students, failed one himself.
‘After a neuro-ophthalmology referral to a colleague, it was established that he had a benign pituitary tumour that was successfully removed. His colour vision returned to normal. He practised very successfully in a private clinic after graduation,’ Professor Adams said.
At the optometry school at Adelaide’s Flinders University, they expect to see a student with colour deficiency only rarely because most of their students are young women. Jason Booth, an optometrist who teaches at the school, is able to assist a student with the condition. He has known since childhood that he was a deuteranope.
‘There’s no colour that I can’t perceive, but the reliability of me telling you what colour that is or which colours look similar to me is quite different from what looks similar to “normal”,’ he said.
Mr Booth believes his exposure to optometry through having a colour vision deficiency spurred his interest in the optometry profession as a child. ‘I don’t think anybody has ever done a survey but I think if they did, [they would find] there’s probably a higher rate of screwy eye balls in the optometry profession than in the general population,’ he said.
About half of the eight per cent of males who have colour vision defects have a condition that is mild enough to have very little impact on their daily lives, unless their vocation calls for fine colour discrimination.
For optometrists, the areas in which a colour vision deficiency presents a problem are few and the adaptive responses are well-established.
No need to screen students for CVD
Routine colour vision screening programs for school students should not be adopted and the existing programs should be discontinued, authors of a review published in Clinical and Experimental Optometry have concluded.
Their paper ‘Is screening for congenital colour vision deficiency in school students worthwhile?’ highlights that congenital CVD presents no barrier to completing a range of common tasks and occupations.
They cite that CVD does not preclude someone from obtaining a drivers licence, or increase the risk of being involved in a traffic collision, and that there is no association between having CVD and level of educational achievement.
The authors found that congenital CVD could not be described as an important health problem and therefore did not warrant inclusion within screening programs for school students.
The authors have recommended that it may be worthwhile for career advisers to refer school students to an optometrist for colour vision screening if they express an interest in an occupation where normal colour vision is either particularly desirable or is a regulatory requirement.
Lead author of the article, Nishanthan Ramachandran, said routine colour vision screening was recommended by the Ministry of Health in New Zealand and was part of the national vision and hearing protocol.
‘I can say from speaking with a vision hearing technician in New Zealand that this is common practice. We also came across similar recommendations and guidelines in some states of the USA, such as Iowa, Arizona and New York,’ he said.
Mr Ramachandran found historical evidence that colour vision screening had been part of routine vision screening of school students in both Australia and the United Kingdom.
Clin Exp Optom 2014; DOI:10.1111/cxo.12187