Back in the early 2010s, when Rohit was a kid, becoming a pilot was all he wanted. He worked hard to achieve his goal as well. However, when he underwent an eye check, as sharpvision is important in the profession, his dreams came shattering down. He came to know he was suffering from colour blindness.
“When he came to me, the patient was depressed. I consoled him, assuring him that he can choose any job other than that of a pilot, which does not insist on a person with normal colour vision,” said Dr Susheela B Nair, senior consultant, department of ophthalmology at KIMSHEALTH, Thiruvananthapuram.
“The problem with inherited colour vision deficiency (CVD) is that it is irreversible and incurable. It is passed down by the parents to the child, mainly due to defects occurring in the cone cells of the retina. These are specialised nerve cells responsible for processing red, green, and blue light,” she added.
Inherited colour blindness does not mean the person does not see colour at all. A person who has got problems with those particular pigments or the cones in the retina is not able to differentiate between colours. So, nobody sees everything as black and white, and they are not completely colour blind. Thus, it is called a ‘colour vision deficiency,” said Dr Sneha Giridhar.
According to studies, inherited or congenital colour vision deficiency (CVD) affects 1 in 12 men (8%) and 1 in 200 women (0.5%) globally. The gender gap occurs because red-green colour blindness is an X-linked recessive trait tied directly to the X chromosome.
“The defect is seen in the X chromosomes. Since males have only one X chromosome, it usually manifests in males. The male pattern of chromosomes is XY, and these are also the sex chromosomes. Females, even though they have one affected chromosome, have 2X chromosomes, and hence, they do not manifest colour blindness. This difference remains one major reason for the differences between men and women. The rough ratio between men and women is 4:1,” Dr Susheela added.
Inherited CVD is diagnosed with the help of certain tests, including Ishihara’s charts, Holmgren’s wool, the Edridge-Green lantern, etc. “Mostly, people during their childhood are unaware of the condition, leading to a delay in diagnosing CVD. In most cases, it does not affect the child’s learning because, unlike refractive errors, colour vision defects themselves do not affect the acuity of vision, either distant or near vision,” she added.
According to Dr Sneha, there is no established medical treatment for colour blindness, but there are ways to manage it. It only works for congenital colour weakness and does not work for acquired colour blindness. “Special glasses, like EnChroma, use a notch filter to block the specific wavelengths of light where red and green overlap, forcing the brain to see higher contrast. For everyday workarounds, people use smartphone apps to speak colours out loud, rely on the memorised position of things like traffic lights, and logically organise or label their clothes,” she added.
Dr Susheela recalls meeting Rohit around five years ago – he was happy and working as an IT professional in a company based in Thiruvananthapuram. “Family and friends play a major role in helping children with the defect. They should be guided in dealing with issues related to colour blindness and choosing the right profession,” she emphasised.