Colour Blindness or Colour Vision Deficiency?

People who struggle to recognise colours are not colour blind.  They can see colours, but they have trouble differentiating between different colours and shades.  They are colour vision deficient and not colour blind.

How Common is Colour Vision Deficiency?

Colour vision deficiency is a genetic condition.  Colour vision information is only available on the X chromosome. 

Women have two X chromosomes and men have one, so if a woman inherits one defective colour vision gene and one good colour vision gene, then the good gene takes over and they are not affected by colour vision deficiency.
They must inherit two defective genes at the same time so the chances of a woman having a colour vision deficiency is 1/200 or 0.5%.
Unfortunately for men, if they inherit a bad colour vision gene then they are doomed to colour vision deficiency.
Men have a 1/12 or 8% chance of having a colour vision deficiency

What are the Symptoms of Colour Vision Deficiency?

Seeing the world in its full spectrum of colours is a gift that many of us take for granted. Imagine a world where the vibrant hues of a sunset or the rich tapestry of a rainbow remain hidden, a world where distinguishing between certain shades becomes a challenge. This is the reality for individuals with colour vision deficiency, a condition that affects how they perceive and differentiate between colours. 

While most people with this condition are not completely blind to colour, they have difficulty distinguishing between certain hues.  
Symptoms can range from mild to severe, profoundly affecting your everyday life. Fortunately, effective methods exist for diagnosing and managing colour blindness.

Whether you suspect you may have this condition or just want to learn more about it, this article will provide you with the information you need.

What are the Different Types of Colour Vision Deficiency?

Our eyes see colour by mixing various intensities of red, green, and blue light in the same way that a TV set does. The receptors in our retina that detect colour are called cones and we have a mix of cones that detect either red, green, or blue light individually. 
This information is relayed to the brain where the data from the three cone sets is mixed to determine an overall colour perception.

If we have an absence or a significantly reduced amount of one type of cone, then a colour vision deficiency will occur.  You can have different degrees of colour vision deficiency depending on how many of the deficient cones you are born with.

If we are missing the red cone then we have protanopia, if we have a reduced number of red cones then this is referred to as a protanomaly.

If we are missing the green cone then we have deuteranopia, if we have a reduced number of green cones then this is referred to as a deuteranomaly.

 If we are missing the blue cone then we have tritanopia, if we have a reduced number of blue cones then this is referred to as a tritanomaly.

What is the Most Common Type of Colour Vision Deficiency?

The most prevalent form of colour vision deficiency is deuteranomaly.
Deuteranomaly and deutanopia represent over 80% of all colour vision deficiencies. 
Most of the other colour vision anomalies are protanomaly or protanopia.
Tritanopia is very rare. 

For those affected by deteranopia or protanopia, it can be challenging to differentiate between certain shades of red and green, however people with protanopia are more significantly affected by their colour vision deficiency.

How can a Colour Vision Deficiency affect your life?

Colour vision deficiency can affect which profession you will be able to perform.  Some professions which may prohibit colour vision deficient applicants include electricians, sailors, police, and firefighters.

While there is no cure for colour vision deficiency, optometrists can use certain tools and technologies to help individuals with this condition.  

Interestingly, colour vision deficiency also occurs in some animals.

Symptoms of Colour Vision Deficiency

If you have a colour vision deficiency, then you will compensate for the lack of information from one cone by using brightness cues.

Deutans (people suffering from either deuteranopia or deuteranomaly) and protans (people suffering from either protanopia or protanomaly) struggle with colours along the “tomato line”.  This represents the colours that a tomato turns as it ripens.  Red is less bright than orange, which is less bright than yellow, which is less bright than green.

Confusion occurs when a colour is brighter or duller than it would normally be.  For example, a bright orange may be mistaken for yellow or even green and a dull orange will be labelled red.

Some of the ways that this could affect a person with a colour vision deficiency are as follows:

• Reduced Sensitivity to Colours – People with colour vision deficiency will experience reduced sensitivity to colours, leading to challenges in everyday activities such as reading maps, identifying traffic lights, or selecting clothing based on colour coordination.
• Confusion with Red and Green – Struggling to distinguish between red and green can be incredibly frustrating for individuals with colour deficiency. It not only impacts their daily tasks but also causes feelings of confusion and helplessness.
• Difficulty in Identifying Colourful Objects – Having difficulty identifying colourful objects can be frustrating and disorienting for individuals with colour deficiency. Understanding their challenges is important in creating a safer environment and providing necessary support for those with colour deficiency.
• Impaired Vision in Dim Lighting – People with colour vision deficiency may find it challenging to see clearly and navigate their surroundings in dim lighting, creating a sense of unease and vulnerability.  Impaired vision in low light conditions is a common symptom of colour blindness, often referred to as night blindness. It can result in difficulty distinguishing objects, reduced depth perception, and an increased risk of accidents.  This visual impairment highlights the importance of taking precautions and utilising aids such as additional lighting or assistive devices to ensure safety.

Diagnosing Colour Vision Deficiency

Colour vision testing involves assessing an individual’s ability to perceive and distinguish different colours. This is usually done using specially designed charts or plates and is what is typically used in practice to determine colour vision deficiency.  

A colour vision deficiency could be determined from genetic testing as well, but this would be a longer and more labour-intensive process and wouldn’t give you any more meaningful information. This would involve analysing an individual’s DNA to determine if they carry any genetic mutations that may be responsible for their colour vision deficiency. There are three main methods of measuring Colour Vision Deficiency

Plate Testing

The most popular plate test is the Ishihara Test which is presented in the form of a book. This test diagnoses if you are a deutan or a protan but is limited in its ability to determine the degree of colour vision deficiency.
Each page has a plate embossed into the pages.
The pages have six types of plate:

Hue Testing

The most popular hue tests in use are the Farnsworth Munsell 100 Hue test or different variations of the D15.  These tests give information on if you are deutan or protan, but are also limited in their ability to determine the degree of colour vision deficiency.  In both tests little plates or discs with various shades of colour printed on their surface are presented to a patient who needs to place them in a continuous order of gradually changing colour.

Anomaloscope

An anomaloscope is a machine where a patient can manipulate controls to mix colours of different brightnesses.  This is the most accurate way to determine the degree of colour vision deficiencies.  It is most commonly used in colour vision research and usually found in Universities.  It is rarely found in private practice.

Living with Colour Vision Deficiency

Living with colour vision deficiency can present challenges, but there are coping strategies that can help you navigate daily life.

• Coping Strategies – Try different colour-coding techniques to help you navigate and organise your surroundings more effectively.  Coping strategies for colour blindness involve finding management techniques that work for you. Seek emotional support from friends and family who understand your condition.

Practical tips include:

• Using labels and markers with high contrast.
• Seek professional advice for specific situations.

Stay proactive and explore different strategies to enhance your daily life.

Support and Awareness

Embrace the support and raise awareness about your colour vision deficiency, allowing others to understand your unique perspective and navigate the world together.  Early detection of colour vision deficiency is crucial to ensure proper support and accommodations.

Eyes By Design Ready to Help Your Colour Vision Deficiency

Eyes By Design, Optometrist Central Coast, is ready to help you with your colour vision deficiency.

Our team of experts is well-informed and professional, ready to guide you in discovering the optimal solution tailored to your distinct requirements.

Trust Eyes by Design to provide you with the support and tools you need for a safer and more vibrant world.

Understanding the symptoms of colour vision deficiency is crucial for those who are affected. Individuals can seek proper diagnosis and support by recognising signs, such as difficulty distinguishing between certain colours or confusion with shades.

With the help of professional optometrists at Eyes by Design, those living with colour vision deficiency can receive the assistance they need to navigate their daily lives. 
Remember, knowledge and support are key in managing and living with colour vision deficiency.
If you have any questions about your vision including colour deficiency – Make an appointment and have a chat with our optometrists

This article is intended to promote understanding of and knowledge about general eye health topics.
It should not be used as a substitute for professional advice, diagnosis or treatment.
Always seek the advice of your health care professional prior to incorporating this as part of your health regimen.

---

Dr Nicholas Altuneg
For over two decades, my greatest passion has been helping people of all ages live improved lives through better vision. At Eyes by Design, vision is so much more than being able to see clearly or read small letters from far away; it determines your perceptions and reactions every second of the day.
Read more about Dr Nick