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What is Colour Vision Deficiency?
Colour Vision Deficiency (CVD) - often referred to as 'colour blindness' - is a condition that affects a person's ability to distinguish between different colours. People with CVD may see colours differently than those with normal colour vision or may not be able to distinguish certain colours at all.
Colour Vision Deficiency is typically an inherited condition that is caused by a genetic defect in the cones, which are the specialized cells in the eye that are responsible for detecting colour. There are three types of cones in the eye that detect different colours, made of different wavelengths of light:
- Red cone cells detect long wavelengths of light
- Green cone cells detect medium wavelengths of light
- Blue cone cells detect short wavelengths of light
When one or more of these cones is not functioning properly, a person may experience CVD.
The most common form of Colour Vision Deficiency is red-green colour blindness, which affects about 8% of men and 0.5% of women of Northern European descent. This type of CVD can range from mild to severe and can make it difficult to distinguish between reds, greens, and yellows.
While there is no cure for colour vision deficiency, most people with the condition are able to live normal, healthy lives by using certain strategies and tools to help them compensate for their colour vision deficiency.
"CVD is most commonly genetic or inherited.
Inherited CVD does not improve or get worse with age.
Most forms of inherited CVD do not affect the eye’s ability to see fine detail."
Different types of Colour Vision Deficiency (CVD)
Red-Green Colour Blindness
The most common form of colour vision deficiency is known as red-green colour blindness, affecting approximately 1 in 12 men and 1 in 200 women. Individuals with this type of Colour Vision Deficiency often struggle to differentiate between red, yellow, and green. Additionally, they may mistake red for black or encounter difficulty distinguishing various shades of purple from blue.
Categorizing CVD by Cones
Colour Vision Deficiency can also be categorized based on which types of cones in the eye are damaged or missing. When the cones responsible for detecting red light are absent or malfunctioning, it is termed ‘protanopia’ or ‘protan colour blindness’.
In cases where the cones for detecting green light are missing or dysfunctional, it is referred to as ‘deuteranopia’ or ‘deutan colour blindness’.
Both protanopia and deuteranopia lead to red-green colour blindness, as the inability to perceive red or green makes distinguishing between the two colours challenging.
Tritanopia: Blue-Yellow Colour Blindness
In situations where the cones for detecting blue light are missing or not functioning properly, the condition is called ‘tritanopia’. Individuals with tritanopia have difficulty perceiving blue, resulting in blue-yellow colour blindness.
Although it is occasionally mistakenly described as blue-green colour blindness, this condition is less common. It affects less than 1% of both men and women. People with tritanopia may struggle to differentiate between blue and green, as well as between yellow and red. Blues may appear as green or even black, yellow may seem white, orange may appear pink, and purple can be mistaken for red.
Achromatopsia or Monochromacy: Total Colour Blindness
In extremely rare cases where two or all three types of cones are missing or damaged, individuals experience total colour blindness, known as achromatopsia or monochromacy. Those with total colour blindness are unable to distinguish any colours and perceive everything in shades of grey.
How someone with Colour Vision Deficiency (CVD) also known as Colour Blindness might view the world
Please note this is a simulation of Achromatopsia or Monochromacy (Total Colour Blindness), based on the anecdotal experiences of people who have the condition. This image is not the experience of everyone with Colour Vision Deficiency (CVD) and is for illustration purposes only.
Symptoms of Colour Vision Deficiency
The most common symptom of Colour Vision Deficiency is difficulty distinguishing between certain colours or shades of colours. This can range from mild difficulty distinguishing between certain shades of red and green to a complete inability to see any colours at all.
Other symptoms of CVD may include:
- Difficulty reading colour-coded information, such as charts, maps, and graphs.
- Difficulty distinguishing between similar colours, such as blue and purple or red and brown.
- Problems with colour-related tasks, such as sorting laundry or picking out matching clothing.
- Seeing colours as washed-out or dull, or perceiving colours differently than others.
It's important to note that not all people with colour vision deficiency experience the same symptoms, and the severity of the condition can vary widely from person to person.
Additionally, some people with mild colour vision deficiency may not even realize that they have the condition until they undergo colour vision testing. If you suspect that you or a loved one may have CVD, it's important to see an optometrist for a comprehensive eye exam and colour vision testing.
"Worldwide 8% of men and 0.5% of women have a red/green type of colour vision deficiency."
Diagnosis of Colour Vision Deficiency
Colour vison deficiency is typically diagnosed through a series of tests that assess a person's ability to distinguish between different colours. The most commonly used tests for colour vision deficiency are the Ishihara Colour Test and the Farnsworth-Munsell 100 Hue Test.
The Ishihara Colour Test involves a series of plates with coloured dots or shapes that are arranged in a specific pattern. Each plate has a number or symbol hidden within the pattern, which is visible only to people with normal colour vision. People with colour vision deficiency may not be able to see the number or symbol and will see a different pattern instead.
The Farnsworth-Munsell 100 Hue Test is a more detailed test that requires a person to arrange a set of coloured tiles in order of hue, from red to purple. This test can help identify the specific type and severity of colour vision deficiency.
In addition to these tests, an optometrist may also use other tools, such as a colour vision screening device, to assess a person's colour vision.
If you suspect that you or a loved one may have colour vision deficiency, it's important to see an optometrist for a comprehensive eye exam and colour vision testing.
"Disease or injury that damages the optic nerve or retina can also cause a loss of colour recognition. These include diabetes, glaucoma, AMD, Sickle Cell Anaemia, Alzheimer's Disease, Parkinsons Disease, MS and leukemia."
Treatment of Colour Vision Deficiency
Currently, there is no known cure for colour vision deficiency. However, there are some strategies and tools that can help people with colour vision deficiency compensate for their condition and improve their ability to distinguish colours.
Some of these strategies include:
Colour-coded labels
Using colour-coded labels for things like medication, clothing, and food can help people with colour vision deficiency easily identify and differentiate between different items.
Assistive Technology
There are several apps, software programs, and devices available that can help people with CVD distinguish between colours. These include colour filters, colour identification apps, and colour correction glasses.
Assistive technology software from Dolphin includes screen magnifiers, screen readers and accessible book readers and text-to-speech software, which can help you navigate your daily life. These tools can make it easier to read, write, study and use technology, as they all have the ability to change and customise colour contrasts for backgrounds, lettering and highlights.
Whatever your experience is with computers, Dolphin assistive technology can help.
Education and awareness
Understanding the limitations of colour vision and learning to recognize and compensate for colour vision deficiencies can help people with colour blindness navigate their daily lives more effectively.
It's important to note that the specific strategies and tools that work best for each person with colour vision deficiency will depend on the type and severity of their condition. A comprehensive eye exam and consultation with an optometrist can help determine the best course of action for each individual.
Living with Colour Vision Deficiency
Living with colour vision deficiency can present some challenges, but with the right strategies and tools, most people with the condition are able to lead normal, healthy lives.
Here are some tips for living with CVD:
Educate yourself
Learn as much as you can about colour vision deficiency and how it affects your vision. Understanding your limitations and knowing how to compensate for your condition can help you navigate daily life more effectively.
Use colour-coded labels and markers
Use colour-coded labels and markers for things like medication, clothing, and food to help you easily identify and differentiate between different items.
Use assistive technology
There are many apps, software programs, and devices available that can help people with CVDdistinguish between colours. These include colour filters, colour identification apps, and colour correction glasses.
Seek accommodations
If you're in school or the workplace, seek accommodations that can help you navigate tasks that require colour vision, such as reading charts, maps, and graphs.
Communicate with others
Let people know that you have colour vision deficiency, and be open about your limitations. This can help others understand your perspective and avoid misunderstandings.
Embrace your unique perspective
Remember that colour vision deficiency is a part of who you are, and it can give you a unique perspective on the world. Don't be afraid to embrace this perspective and use it to your advantage.
