C is for colour blind

Deana Stokes Sullivan
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Some top students can't meet program requirements due to hereditary trait

It might seem hard to believe a straight A student, who has excelled in every subject in high school, wouldn’t meet the requirements for a post-secondary program, but it happens every fall.

This would happen if she received one gene mutation from her father and her mother was a carrier.

Green said she can remember testing one young woman who was colour blind. She knew her father was colour blind as well, she said, but her mother must have been a carrier. The woman’s sons were also colour blind.

“If she had two mutations, then all her sons would get the X with the mutation and be colour blind,” Green said.

Many people are never assessed for colour blindness. Green said they may realize they have difficulty with colours, but don’t have a reason to be tested.

“They know the colour that grass is, is green,” she said, “and even if they don’t see it exactly like somebody else, anything else that is that colour is also green, and so on.”

Some people who are red/green colour blind can also function well, she said. They may not be able to see the colours accurately on a traffic light, but they know the order of red, yellow and green.

In many professions, it doesn’t make a difference, Green said, unless a student plans to pursue a career as a pilot, police officer or in a navigational field.

There are different degrees of color blindness, she said, and the cases being picked up at the Marine Institute are likely in the intermediate level if it wasn’t obvious to the students previously.

Some have no trouble distinguishing between different colours; they just see them slightly different from other people, Green said. But in navigation fields, she said, “you absolutely have to distinguish between red and green” in order to know whether that ship coming toward you is on your left or right.

“People challenge us and say, ‘I want to do this program anyway.’ They can do it, but at the end of it, they can’t work in the field,” Glenn Blackwood said

Over the years, Green said she’s been asked to do colour vision testing and, sometimes, a hereditary disease called cone dystrophy is the cause, where the cones in the retina that can see colour are not working. But in these cases, she said, these people will also have severe decreased vision.

Red/green colour blindness is much more common than most genetic conditions, Green said, but it’s not really a disability for most people. It can make a difference in your career choice, she said, but it’s not an illness.

In classes of about 60 medical students, Green said there’s often two or three male students who are red/green colour blind. She discovers it when she demonstrates how the testing is done using slides with various layers of colours and a number. Anyone with red/green colour blindness doesn’t see a number there, she said, while other students will see a five or seven in the middle of the coloured dots. Some have already known they’re colour blind, she said, while others have had no idea.

While there has been research to correct colour blindness in animals, Green said gene therapy is a long, complex process and researchers are not near the point of testing this out in people.


Organizations: Marine Institute, Canadian School Boards Congress

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Recent comments

  • Al
    July 28, 2010 - 12:13

    This reminds me of early 1970 when nine of us students went to the recruiting centre in St. John's to join the military. Only three of us actually made it through. Apparently the rest were color blind and couldn't qualify. Even then I couldn't understand why six out of nine people (all male) were color blind, but found out later that this was the way the military rejected people they thought were not Armed Forces material. I have to admit though that I believe this was based on opinion rather than fact.

  • Dave
    July 27, 2010 - 14:56

    MUN being accommodating to students. Give me a break, not enough space to tell you what they done to students in the past!

  • Ejcmartin
    July 27, 2010 - 12:13

    I grew up in Toronto and this test was administered in grade six. I was found to be colour blind and told right then what careers I should not pursue. I too can see red and green in most cases, eg. Traffic lights, but I could see the problem if there was an emergency at sea and one had to distinguish quickly between red and green.

  • Ben
    July 27, 2010 - 11:19

    As someone who failed this colour blindness test refered to in this article as I could not read any number in a book of 21-22 when tested, however I have no problem seeing the difference in a red or green traffic light, and I can distinguish navigational bouys or aids at sea. For my job , I had to pass a color blindness test also, but there is a second test where they test your ability to distinguish colours administered, which I can pass with ease. I dont think you should reject someone based on this test alone. I bet a lot of this people could tell the colours like myself if given the opportunity. I dont think this test alone is valid to call someone colour blind. Im proof it isnt accurate.

  • Debbie Mackey
    July 27, 2010 - 08:21

    Just a thought - Can't symbols be put in with the Colour to differentiate? This has probably been suggested before!!