Colour Blindness

Colour blindness manifests as distinguishing between specific colours, which can affect millions worldwide, impacting their daily lives subtly yet significantly. This condition makes it challenging for individuals to perceive differences between various hues, particularly reds and greens. Understanding colour blindness, its types, causes, and symptoms is crucial for early detection and management. 

What is Colour Blindness? 

Also known as colour vision deficiency (CVD), colour blindness is a condition that impairs an individual's ability to perceive colours accurately. It occurs when the cones, light-sensitive cells in the retina, don't function properly. These cones are responsible for processing light and sending signals to the brain, thus creating a mechanism to distinguish between different hues. 

Types of Colour Blindness 

Colour blindness manifests in various forms, affecting an individual's ability to perceive colours differently. 

• Red-green Colour Blindness: The most common type is red-green colour blindness, which includes two subtypes: 
  • Deuteranomaly: This is the most prevalent type of colour blindness that causes certain green shades to appear more red. 
  • Protanomaly: This type makes some red shades look greener and less bright. 
• Blue-yellow Colour Blindness: Though less common, it also exists in two forms. 
  • Tritanomaly: This type makes differentiating blue from green and yellow from red challenging. 
  • Tritanopia: It causes more severe difficulties in distinguishing these colour combinations. 
• Complete Colour Blindness: The rarest form is complete colour blindness or monochromacy, where individuals see no colours. This condition affects approximately one in 33,000 people. 

Causes of Colour Blindness 

The following are common colour blindness causes: 

• Genetics Factor: The condition is typically inherited and passed down through genes on the X chromosome. This inheritance pattern explains why red-green colour blindness affects men more frequently than women. Mutations in specific genes, such as OPNILW, OPNIMW, and OPNISW, can lead to different types of colour vision deficiency by affecting the function of cone cells in the retina. 
• Besides genetic factors, colour blindness can also be acquired later in life through: 
  • Chronic illnesses like diabetes, glaucoma, and multiple sclerosis may cause colour vision loss. 
  • Accidents or strokes affecting the retina or specific brain areas can also result in colour blindness. 
  • Antibiotics & blood pressure drugs have the potential to impact colour perception. 
  • Exposure to industrial chemicals can also contribute to developing colour vision deficiencies. 
  • The natural ageing process can develop colour blindness. 

Colour Blindness Symptoms 

Colour blindness often goes unnoticed, as individuals may not realise they perceive colours differently. 

• The primary colour blindness symptom is difficulty distinguishing between certain hues, particularly reds and greens. People with colour blindness might struggle to distinguish different shades of these colours. Some may confuse blue and yellow tones as well. 
• In children, signs can include using incorrect colours when drawing, such as purple leaves on trees or showing a lack of interest in colouring activities. 
• Adults might have trouble interpreting colour-coded materials or traffic lights. Interestingly, some individuals with red-green deficiency learn to associate the 'right' colour with objects, like calling tree leaves green, even if they perceive them differently. 

Diagnosis of Colour Blindness 

Diagnosing colour blindness involves several tests to assess an individual's ability to perceive colours accurately. 

• Ishihara Test: It is widely used by eye specialists worldwide and consists of plates with coloured dots forming numbers or shapes. These patterns are visible to those with normal colour vision but challenging for individuals with red-green colour deficiencies. The test's sensitivity ranges from 96.55% to 98.28%, depending on the number of errors allowed. 
• Aanomaloscope: This diagnostic test is considered the gold standard for colour vision testing. It requires patients to match different light sources, allowing for precise evaluation of colour perception. 
• Farnsworth D-15 and Farnsworth Munsell 100 Hue Tests: These tests involve arranging coloured chips in order, helping to determine the type and severity of colour blindness. 

Treatment of Colour Blindness 

While there's no cure for inherited colour blindness, various strategies can help manage the condition. 

• Special contact lenses and glasses can enhance colour contrast, making it easier to distinguish between hues. These aids don't create new colours but improve colour perception for some individuals. 
• Technology also plays a role, with applications and software helping people identify colours in their surroundings. 
• For those with acquired colour blindness, treating the underlying condition or adjusting medications may improve colour vision. 
• Adapting daily routines, such as organising clothing by colour or memorising traffic light positions, is crucial. 

When to See a Doctor 

Consult an optometrist or ophthalmologist if you have trouble distinguishing colours, especially reds and greens. Early detection is vital for children, mainly if there's a family history of colour vision deficiency or if they struggle with colour-related tasks. 

Prevention 

While inherited colour blindness cannot be prevented, one can take a few precautionary measures to lower the risk of acquired colour blindness, such as: 

• Regular eye check-ups are crucial to monitor eye health and identify potential issues early. 
• A healthy lifestyle can preserve vision. A diet comprising a good source of omega-3 fatty acids, found in cold-water fish, and antioxidants from leafy green vegetables may support eye health. 
• Protecting eyes from UV rays by wearing sunglasses and maintaining good contact lens hygiene are essential preventive measures. 
• Practising the 20-20-20 rule can help reduce eye strain (Seeing an object 20 feet away for 20 seconds after every 20 minutes of screen time) and potential vision problems for those who spend long hours in front of screens. 

Conclusion 

Colour blindness significantly impacts how individuals perceive the world around them. This article has shed light on this condition's various types, causes, and symptoms, emphasising the importance of early detection and proper diagnosis. The available tests, such as the Ishihara plates and the anomaloscope, play a crucial role in identifying colour vision deficiencies accurately. While there's no cure for inherited colour blindness, various strategies and tools can help people manage their condition effectively. 

FAQ's 

1. Who does colour blindness affect? 

Colour blindness affects approximately 8% of men and 0.5% of women worldwide. The condition can happen in people of all ages, but it's typically detected in childhood. 

2. How common is colour blindness? 

Colour blindness influences about 350 million people globally. In Indian males, the prevalence is 3.89% and in females it is 0.18%. 

3. Can we cure colour blindness? 

Currently, there's no cure for inherited colour blindness. Addressing the underlying cause of acquired colour blindness may improve colour vision. Special lenses and glasses can enhance colour perception for some individuals, making it easier to distinguish between hues. 

4. How do I know if I'm colourblind? 

Signs of colour blindness include difficulty distinguishing between certain colours, particularly reds and greens. You might struggle with colour-based tasks or notice that you see colours differently. 

5. What to eat for colour blindness? 

While diet can't cure colour blindness, certain nutrients support overall eye health. Foods rich in vitamins A, C, and E and omega-3 fatty acids may benefit eye function. Green leafy vegetables, colourful fruits, dairy products, fish, and nuts are good choices. 

6. How serious is colour blindness? 

Colour blindness is generally not severe and doesn't affect overall vision. However, it can impact daily life, education, and career choices. 

7. Can Colour blindness go away? 

Inherited colour blindness is a lifelong condition and doesn't go away. However, if colour blindness is acquired due to an underlying health problem or medication, treating the cause may improve colour vision. 

8. At what age is colour blindness detected? 

Colour blindness is usually detected in childhood, typically between ages 4 and 10. It often becomes apparent when children struggle with colour-based activities or show difficulty identifying specific colours. 

9. Who is at risk for colour blindness? 

Males have a higher risk of colour blindness due to genetic factors. Those with a family history of colour blindness, particularly on the mother's side, are more likely to be affected. Certain systemic conditions, such as diabetes, multiple sclerosis, and glaucoma, can increase the risk of acquired colour blindness. Additionally, exposure to certain chemicals or medications may lead to colour vision deficiencies.

Dr. Neelu Agrawal

CARE Medical Team

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