Understanding colour blindness: Causes, symptoms, and management

Colour blindness, clinically known as a colour deficiency, is a visual impairment where individuals struggle to perceive colours as the majority do. 

While some may find it challenging to differentiate between specific colours, others may only perceive shades of black and white. This condition, termed achromatopsia, though rare, significantly impacts an individual's perception of the world around them.

Signs and symptoms

Symptoms of colour blindness can vary in severity, with many individuals exhibiting mild symptoms that often go unnoticed. The primary indicator is difficulty distinguishing between certain colours or frequent mistakes in identifying them. Commonly affected colour differentiations include shades of red and green or, less commonly, green and blue. Additionally, individuals may struggle with discerning colour brightness.

In severe cases, symptoms may include rapid, uncontrollable eye movements (nystagmus) or heightened sensitivity to light. However, these manifestations are less common.

Causes and risk factors

Colour blindness is primarily hereditary, with genes inherited from parents playing a crucial role. It occurs due to a partial or complete lack of retina cones, which detect red, green, and blue colours. 

While congenital colour blindness is most prevalent, certain factors can lead to acquired colour vision deficiencies. These may include diseases affecting the eyes or metabolism, damage to the eye or brain, age-related cataracts, or specific medications.

Men are at a higher risk of inheriting colour blindness compared to women. Individuals with a family history of colour blindness or those with certain health conditions, such as diabetes or multiple sclerosis, are also more susceptible.

Diagnosis and management

Diagnosing colour blindness typically involves a simple eye test, often conducted by optometrists during routine vision screenings. The Ishihara colour test, where individuals identify numbers hidden within coloured circles, is a common method used for diagnosis.

While there is no cure for inherited colour blindness, individuals can manage the condition through various means. Special glasses or contact lenses may help some individuals distinguish between colours. Additionally, smartphone apps designed for colour vision deficiencies can assist in identifying the colours of objects. Simple strategies, such as memorising the order of coloured items or seeking assistance from others with normal colour vision, can also be helpful.

Prevention and complications

Genetic colour blindness cannot be prevented; however, certain measures can reduce the risk of developing acquired colour vision deficiencies. Regular check-ups with healthcare providers, eye examinations, and a healthy lifestyle may help maintain optimal visual health.

For individuals with severe colour blindness, such as achromatopsia, complications may include sensitivity to light, reduced visual acuity, and uncontrollable eye movements. Although rare, these complications can significantly impact an individual's quality of life.

Research and statistics

Red-green colour blindness is the most common form, affecting approximately 8 per cent of men of northern European ancestry, compared to 0.5 per cent of women. Blue-yellow colour blindness, impacting men and women equally, is less prevalent, affecting fewer than 1 in 10,000 individuals worldwide.

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