Common colour vision problems
On this page we report what colour-blind doctors and medical students have said about the problems they have had with colour in their practice of medicine or in medical school.
What doctors say.
What medical students say.
What colour-blind doctors say
Forty colour-blind medical practitioners completed a questionnaire about the problems they had with colour in their practice of medicine. They had volunteered to do so in response to an invitation letter in the medical press. Here are some of their comments (ref 47):
• “You do not necessarily know when you have a problem – others point them out.”
• “I was aware of my colour blindness before going to medical school, but I only realised (after being qualified for 6 years) why I was useless at certain things, e.g. histology, clinical examination. My loss of confidence might have been sympathetically handled by medical school staff had they been on the lookout for this situation.”
• “I did a year in pathology and did not realise that stains showed different tissues – no one had told me. My eyes pick up very fine detailed physical features of rashes etc. I feel this and body language are major advantages I have developed. I frequently ask my colleagues for advice, particularly over babies with rashes and fevers etc. and the chance of a red ear or throat. I feel I am very vulnerable at the end of a surgery. I believe there are times when patients describe red rashes and I cannot see them and nurses point out the invisible dots.
• “I once diagnosed a haematemesis as bile. The patient was lucky to survive.”
• “Nowadays I am a trainer for young physicians in vocational training and advertise my own handicap in order to teach the young people to do the same, and then we consciously develop methods to overcome the problem.”
• “The problem is I do not know what I am missing.”
Go to “Confessions of a colour blind physician” (ref 50) for more.
The graph shows the percentage of the 40 doctors with abnormal colour vision who reported on the problems they had with specific colour tasks in their practice of medicine or during their medical course.
An ophthalmologist in Canada wrote:
…I am green blind – it came from my mother’s father…I knew I was deficient at an early age but just buzzed along with hockey, football, cricket. In medicine I got a high mark in biology and anatomy (no colour problems). In physiology I was introduced to the Ishihara test and learned the details. In bacteriology I could not identify the tubercle bacilli with the Ziel Neelson stain (got 0.00 % in that test). I could not pick out by colour the trachoma virus, only by shape. I was getting smart and was very cagey about naming rashes, especially diffuse ones with no border. I decided dermatology was not for me. I was always good at mathematics and made a voluntary decision into ophthalmology on that basis.I did some mathematics and assisted in the design of the Hardy-Rand-Ritter- Plates and found that Ishihara had gone through the same steps we did years before. In the RCAF I assisted with work on camouflage, aircraft spotting and recognition, night vision, instrument design and placement. There were others to check if there were errors in colours. After the war I did a lot of ophthalmic pathology, but there were always others in the lab. to check colours. One thing that came from my Daltonism was an interest in genetics, and I published on a number of ophthalmic hereditary diseases. Finally I was relegated to being a chief and then all I did was to encourage others… I do think that a student should know what his problem is, the deficiency and the resultant hazard. He can mold his career to fit his colour defect, going to paths where there are other strengths and no hindrances from colour defect. I did counsel a number of medical students and residents, with happy results. I did bring the subject up at medical school committee meetings but roused little interest.
Letter from Clement Whillard – Toronto – 1993
What colour-blind medical students say
Burke (refs 15, 16) asked 155 medical students an open question about the difficulties they may have experienced in their learning or assessment at medical school as a result of their colour vision deficiency.
A third of them reported difficulties, including:
| Interpreting histological slides |
14
|
| Distinguishing dermatological lesions |
10
|
| Detecting cyanosis |
9
|
| Reading projected slides |
7
|
| Interpreting microbiological stains |
7
|
| Reading dipsticks |
6
|
| Detecting pallor |
5
|
| Detecting inflamed tympanic membranes in otitis media |
4
|
| Identifying canulas by coloured caps |
4
|
| Following the laser pointer in lectures |
4
|
| Optic disc assessment |
3
|
| Recognising erythema |
3
|
| Distinguishing venous from arterial blood |
1
|
63% said they would benefit from advice from their medical school or the occupational health department about the implications of their colour vision deficiency in clinical practice.
When asked: “If you were given the opportunity to have thorough colour vision testing to tell you the exact type of colour blindness that you have, as well as its severity – do you think that knowledge would be useful to you in terms of your future career?” 74% said yes.
These are some of the replies to a question about any career advice they had had about their abnormal colour vision since starting at medical school:
“One surgeon told me it would be hard to do surgery but he did not say why.”
“I want to choose a specialty in which colour vision is not going to be a disadvantage to me but I am unsure how to find out.”
“I saw an occupational health doctor, who said I might have difficulties in some careers, but did not know which ones.”
Coloured pills and colour-blindness
Colour is used on pill bottles and pill caps to help identify and distinguish different kinds and different strengths of medications. Pills and tablets are also often coloured for the same reason. People with the more severe form a colour vision deficiency will have problems recognising the colours, as the picture shows. (ref 65). The colours in the bottom picture have been transformed to the appearance of a person with a protonopic colour vision deficiency. Doctors should not use colour names to identify medicines to their patients unless they know their patient has normal colour vision. Instructions like “take the green pill in the morning and the pink one at night” may bewilder colour-deficient patients who cannot distinguish green and pink. The colour-blind doctor might also have a problem when a new patient says “I take the green pill in the morning and the pink one at night”
