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Colour blindness: Seeing the world in a different light

Colour blindness: Seeing the world in a different light

Early screening of colour vision is as important as regular vision screening, say experts
Child getting tested for colour blindness
Representational Image | Shutterstock

Ezra Johnson (8), from Alberta, Canada, has had achromatopsia since birth. He also has reduced vision and Moreover, he is sensitive to bright lights, says his mother, Jade Johnson.

Persons with the genetic condition achromatopsia visualise the world in black and white as they cannot perceive colours.

The Johnsons’ buddy dog Patsy, trained under a guide-dog programme conducted by a Canadian institute to support visually challenged people, supports Ezra emotionally.

Ezra’s parents were carriers of the genes responsible for achromatopsia and were not aware of the genetic mutation until they were diagnosed as carriers when their child was 2.5 years old.

Ezra wears a special glass with a red tint to manage different lighting situations during the day. However, he does not use glasses during the night as he can identify objects in low light without difficulty. He can communicate if he needs help in most situations and his mother helps him out with modifications that can ease the situation for him.

“Though he faces some challenges in socialising with his friends during playtime and in school, he stays motivated and has learned to manage his day-to-day activities. He is creative and loves to make his own food too,”

Ezra relies on magnifying tools in iPads to help him with reading and writing. He gets help from his class teacher in school. Though there is no treatment for his condition, the Johnsons are hopeful of a healthy life for Ezra.

What is colour blindness?

Individuals with colour blindness or colour vision deficiency are unable to identify green, red and blue. That is because the retina has two types of cells, namely the rods and cones. Rods are responsible for night vision while cones are responsible for day vision and aids in detecting different colours.

Our brain receives signals from these cones and helps in visualising colours. Colour blindness occurs when one or more colour cones are absent or do not work. Though such persons are unable to perceive the exact shade of the colour, they can visualise the colour in the closest shade.

A study was conducted among children in the 6 to 15 age group from different schools in Jalandhar, Punjab to determine the prevalence of colour blindness. The results showed that boys were more affected than girls.

Individuals with mild colour blindness may face difficulty in identifying colours either in the absence or presence of light. People with severe colour blindness perceive everything in shades of grey. However, a severe form of colour blindness is a rare condition.

What are the causes

Dr Bhaskar Raja, an ophthalmologist from Coimbatore, says that colour blindness occurs due to congenital (hereditary) and acquired causes. The acquired causes include optic nerve injury due to trauma or macular degeneration (damage to a part of the retina) due to uncontrolled diabetes and hypertension.

Diagnostic methods

“A pseudoisochromatic test is commonly used in clinical practices. It is a simple test and helps to identify whether the individual has red or green deficiency. However, the degree of colour deficiency can only be determined with other comprehensive eye examinations,” Dr Raja says.

individual is asked to read the number present in between multi-coloured dots. People with colour blindness find it difficult to identify colour patterns and numbers.

Dr Jayshree Arunaprakash, an ophthalmologist from Dr Agarwal’s eye hospital, Coimbatore, says that children should be taken for regular check-ups for colour vision early in life, as the chances of developing this condition later in life is minimal.

Certain professions like those of pilots, drivers, chemical engineers, textile industry workers, and designers rely on colour perception. Many individuals realise they have the condition only during interviews for jobs where colour matters. As such, it is better to screen for the condition during early schooling.

“During my practice, I have seen an individual who was not aware of colour blindness until 67 years of age. Since colour vision deficiency does not create a major impact in vision, individuals remain unaware most of the time,” says Dr Raja.

Managing the condition

There is no treatment for inherited colour blindness, but if the cause is eye injury, diabetes, or hypertension, then managing the conditions will help in improving colour vision.

“Wearing special tinted glasses can increase individuals’ ability to differentiate colours but they cannot visualise the deficient colour completely,” says Dr Arunaprakash says.

“Though colour blindness is an irreversible condition, it remains stable throughout life. If there is low vision associated with colour vision deficiency, then the management is done accordingly,” says Dr Raja. Organising or labelling things with the help of friends or family aids in easier recognition of coloured objects.

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