by on April 27, 2017

in Uncategorized

Colorblindness, also known as Color Vision Deficiency (CVD), affects 1 in 12 boys and 1 in 200 girls. It is genetically transmitted via the X-linked chromosome and thus CVD is far more common in boys. It works like this: a grandfather, who is color blind, is very likely to transmit CVD to his grandson, via his daughter.

Many children are diagnosed at a later age simply because they were not screened appropriately or there was a lack of awareness on the part of teachers, parents and even some clinicians.

According to a landmark study done in 5960 California children between the ages of 30 and 72 months regarding the testability of CVD, only 17% of children younger than 37 months of age could be tested; 57% of children 37 to 48 months could be tested reliably, and by age six years 98% of children could be tested with confidence.

The same study determined the prevalence of CVD in boys was 1.4% for black boys, 3.1% for Asian boys, 2.6% for Hispanic boys and 5.6 % for non-Hispanic white children.

We have three types of cone cells in our retinas, each type being responsible for detecting either red, green or blue light. In colorblindness one type is unable to decipher light wavelengths correctly. As a result, the brain receives incorrect information and cannot properly interpret color. The most common situation is a child who finds it hard to distinguish between red and green colors. They also have a hard time to detect purple and brown colors.

Rare forms of CVD exist such as blue blindness and monochromacy. The latter condition has intrigued many scientists because of its peculiar presentations. In his well-written, New York Times bestselling book An Anthropologist on Mars, the late Dr. Oliver Sacks, then a neurologist, described a curious case of a colorblind painter. The painter was involved in a car accident and was told he had a concussion. However, he also told clinicians that he could only see in black and white. Various ophthalmologists and neurologists were at a loss to explain this rare event.

In another book, The Island of the Colorblind, Sacks writes about how he became intrigued by a tiny Pacific atoll where an isolated community of islanders were born totally colorblind (a condition known as acromatopia)

The screening of CVD in a younger child can be done by parents using an App or the Ishihara 38 Plates Color Blindness Test (See Ultimately an eye doctor will have to give the final verdict.

CVD may be suspected when a child uses the wrong colors consistently for an object (e.g. purple leaves on trees); when there is a drop in attention when coloring in worksheets; when there are problems identifying red and green pencils; when a child smells food before eating it; or when children complain that their eyes hurt or they have headaches when looking at something red on a green background or vice versa.

Some of these children may incorrectly be labeled by teachers as having attention span deficiencies or being learning disabled.

In the UK school CVD screening used to be available, but now it has been phased out. Kathryn Albany-Ward, the founder of the UK-based Color Blind Awareness group, teamed up with British School Nurses to determine why so many teachers fail to consider color blindness when a child struggles to learn or misbehaves in class. General information about what parents and teachers can do together to identify CVD earlier can be found on (There is also a support group via Facebook for families with children who have CVD: use the search box function of Facebook and enter the words “ colour blind awareness”)

In my 30-year career as a pediatrician, I have learned so much from parents and children as my teachers. I was enlightened recently when I read about a mother’s journey into colorblindness which appeared in a guest article on the site,

Colorblindness may preclude future careers as airline pilots, firefighters, policemen and electricians. However civil rights issues and the definition of being handicapped by CVD has led to controversial battles and stimulating conversations. Visit and enter the word “career” in the search box for more information about regulations and rules for pilots and police officers and concerns over doctors who are colorblind and thus limited to diagnose certain conditions.

In some countries drivers’ licences are withheld from color blind individuals depending on the degree of CVD.

Children with CVD should have teachers who are informed about this condition and who will ensure that settings are color-blind-friendly (such as labelling crayons, seating students in good light and looking out for students who hold back on sports when team colors clash or line markings “disappear”)

When a colorblind boy grows up and gets married, he may need a wife who can help him match his clothes—and if the couple is into playing trivial pursuit, I highly recommend this website:


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