What is Colour Vision Deficiency?
Colour vision deficiency (CVD), often called “colour blindness”, affects how the eye perceives certain hues and is one of the most common variations in eye function that we come across. In fact, it affects around 1 in 12 men and 1 in 200 women—a quirk of X-linked genetics. Contrary to popular belief, most people with CVD don’t see the world in black and white, but rather struggle to distinguish between reds and greens, or blues and yellows.
What are the signs of CVD?
In mild cases, it often goes unnoticed until school-age testing, which is one of the reasons why we recommend eye tests for small children. It’s important to know at school so that children don’t get chastised for using surprising colours in artwork or get confused by colour-coded equipment. Later, it is important for career choice as a small number of careers can be restricted for people who don’t see the full range of colours. In aviation, electrical work, and certain roles in the emergency services or armed forces, precise colour discrimination is essential, and a small number of roles may be ruled out. However, in everyday life, CVD is rarely an issue as the vast majority are born with it, and their colour vision is ‘normal’ to them.
In adulthood, rare cases of colour vision issues can develop later in life due to conditions like glaucoma, diabetes, macular degeneration, or optic neuritis, which we assess for in our eye examinations.
What can I expect?
Colour vision differs in humans from that of other animals; some—like bees—see ultraviolet light, while dogs perceive fewer colours than humans. Evolutionarily, colour vision in humans likely helped our ancestors spot ripe fruit and snakes in leafy undergrowth. Interestingly, research suggests variations in prevalence across ethnicities, with CVD less common in people of African and Asian descent compared to European populations.
Diagnosing CVD
At Rawlings, we use accurate tests, including Ishihara plates and the TCU test, to diagnose and grade CVD. Though there’s no cure, coping strategies—from labelled wardrobes to colour-assistive apps—can make a world of difference. Colour-enhancing contact lenses and spectacle lenses are available but rarely used, as although they enhance, they still don’t produce the same colour vision as a person with full colour vision would experience.
If you or your child has concerns about colour vision, rest assured: life can still be vibrant, successful, and full of opportunity—with the right support and advice. If you notice a change in your colour vision as an adult, this indicates that you should contact us to arrange an eye examination to rule out disease.
