Colour Vision Deficiency
Colour-Enhancing Lenses

What Is Colour Vision Deficiency?
Colour vision deficiency (CVD) is a condition in which a person has difficulty distinguishing certain colours or differences between colours.

It is often commonly referred to as colour blindness, although the term can be misleading.
Most people with colour vision deficiency are not completely unable to see colour.
Instead, certain colours may appear more similar to each other and can therefore be more difficult to distinguish.
For example, someone may have difficulty differentiating particular shades of:

• Red and green

• Green and brown

• Red and brown

• Blue and purple

• Blue and yellow

The exact colours affected depend on the type and severity of the colour vision deficiency.

At Eye Zen Optical in Singapore, we provide personalised optical consultations for individuals with colour vision deficiency and can explore whether specially selected colour-filtering lenses may improve colour differentiation for particular situations.

These lenses do not cure colour vision deficiency or colour blindness.
​Colour Vision Deficiency Is Not Always Complete Colour Blindness
The terms colour vision deficiency and colour blindness are often used interchangeably.
However, there is an important difference in how people commonly understand these terms.
Most people diagnosed with colour vision deficiency can still see many colours.
The difficulty is usually in distinguishing certain colours from one another.
Complete absence of colour perception is much less common.
This is why colour vision deficiency is often a more accurate description than simply saying someone is colour blind.
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How Do We See Colour?
Colour vision begins with specialised photoreceptor cells in the retina known as cones.
Humans normally have three types of cone photoreceptors with different spectral sensitivities.
The brain compares the signals received from these cone systems to create our perception of colour.
When one cone system functions differently from the typical response, certain colours may become more difficult to distinguish.
The effect varies considerably between individuals.
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Types of Colour Vision Deficiency
Colour vision deficiency can occur in different forms.
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Red-Green Colour Vision Deficiency
Red-green colour vision deficiency is the most common category.
It includes conditions affecting the perception and differentiation of colours associated with the red- and green-sensitive cone systems.
Different people can experience very different degrees of difficulty.
Some may only struggle with particular shades, while others may have more substantial difficulty distinguishing colours in the red-green range.
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Blue-Yellow Colour Vision Deficiency
Blue-yellow colour vision deficiency is less common.
People with this type may have difficulty distinguishing certain combinations involving blue, green, yellow or related colours.
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Complete Colour Vision Deficiency
A very small number of people have conditions involving severely reduced or absent colour discrimination.
This is very different from the more common red-green colour vision deficiencies.
Specialised colour-filtering lenses should not be presented as restoring normal colour vision in someone who cannot perceive colour normally.
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What Does Colour Vision Deficiency Look Like?
Colour vision deficiency does not usually mean seeing the world entirely in black and white.
Instead, some colours may appear:

• More similar to one another

• Less distinct

• Muted

• Difficult to identify

• Difficult to separate when placed together

For example, two colours that look obviously different to someone with typical colour vision may appear much more similar to someone with a colour vision deficiency.
The experience varies according to the type and severity of the deficiency.
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How Can Colour Vision Deficiency Affect Daily Life?
Many people with colour vision deficiency adapt very well and experience relatively little difficulty in everyday life.
However, colour discrimination can be important in certain situations.
Examples may include:

• Reading colour-coded charts

• Interpreting graphs

• Identifying coloured indicators

• Selecting clothing

• Distinguishing wires or components

• Recognising colour-coded information

• Certain educational activities

• Some occupations

• Hobbies involving colour identification

People often develop other strategies, such as using position, brightness, labels or context rather than relying entirely on colour.

Can Special Lenses Help With Colour Vision Deficiency?
For some types of colour vision deficiency, specially selected tinted or colour-filtering lenses may alter the way certain wavelengths of light reach the eyes.
This can change the contrast between particular colours.
As a result, some individuals may find certain colours easier to differentiate from one another while wearing an appropriate filter.
For example, two colours that normally appear very similar may become more distinguishable because the filter changes their relative brightness or contrast.
However, the response varies considerably from person to person.
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What Colour-Filtering Lenses Can and Cannot Do
It is important to have realistic expectations.
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Colour-filtering lenses may:

• Alter the appearance of certain colours

• Increase contrast between some colours

• Make particular colours easier to differentiate for some individuals

• Assist with certain colour-identification tasks

• Provide a useful visual aid in selected situations

 
Colour-filtering lenses do not:

• Cure colour vision deficiency

• Change the cone photoreceptors in the retina

• Restore typical colour vision

• Create colours that the visual system is unable to perceive normally

• Guarantee improvement for every person

• Correct every type of colour vision deficiency

The purpose of these lenses is therefore not to cure colour blindness.
Their purpose is to determine whether modifying colour contrast provides a useful visual benefit for the individual.
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Why Can Filters Make Certain Colours Easier to Distinguish?
Imagine two colours that appear very similar to someone with a colour vision deficiency.
Without a filter:
Colour A ≈ Colour B
The visual difference between them may be difficult to detect.
A specially selected filter changes the amount of particular wavelengths reaching the eye.
This can alter the relative brightness or appearance of the two colours.
With an appropriate filter:
Colour A ↔ Colour B
may become easier to distinguish.
The underlying colour vision deficiency has not disappeared.
Instead, the optical filter has changed the visual information reaching the eye in a way that may improve discrimination between certain colours.
This distinction is important.
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Do Colour-Enhancing Lenses Make You See Colours Normally?
No.
A person should not be told that colour-enhancing lenses will make them see colours exactly as someone with typical colour vision sees them.
The lenses alter the visual appearance of colours.
They may improve the ability to distinguish certain colours, but this is not the same as restoring normal colour perception.
Some colours may become easier to differentiate while others may appear different or less natural.
The usefulness of the lens therefore depends on the individual's visual requirements.
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Will Colour-Filtering Lenses Work for Everyone?
No.
Colour vision deficiency varies significantly between individuals.
The effectiveness of a filter depends on factors including:

• Type of colour vision deficiency

• Severity of the deficiency

• Colours the person has difficulty distinguishing

• Selected filter

• Lighting conditions

• Visual task

• Individual response

A filter that provides a noticeable benefit for one person may provide little useful improvement for another.
For this reason, individual assessment and comparison are important.
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How Eye Zen Optical Approaches Colour Vision Deficiency
At Eye Zen Optical, we do not approach colour vision deficiency with the assumption that one particular lens will work for everyone.
Our aim is to understand which colours you have difficulty distinguishing and whether an optical filter provides a meaningful practical benefit.
Depending on your requirements, our approach may include:
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Understanding Your Colour Vision Difficulty
What colours do you commonly confuse?
Does the problem affect work, education, hobbies or particular daily activities?
Understanding the actual difficulty is more useful than simply knowing that a colour vision deficiency exists.
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Identifying the Type of Difficulty
Different colour vision deficiencies affect colour discrimination differently.
The type and degree of deficiency influence whether a particular filter is likely to provide useful assistance.
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Comparing Different Filters
Where appropriate, different colour-filtering options may be compared.
The objective is not simply to make colours look more vivid.
We want to determine whether the filter makes the specific colours causing difficulty easier to differentiate.
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Evaluating Practical Benefit
A colour change is only useful if it provides a meaningful benefit.
The individual should therefore consider whether the filter actually helps with the task for which it is intended.
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Setting Realistic Expectations
We explain clearly that colour-filtering lenses are an optical aid, not a cure for colour blindness.
Their purpose is to modify colour contrast and potentially improve differentiation of certain colours.
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Colour Vision Deficiency in Children
Colour vision deficiency is often inherited and may be present from childhood.
A child may not realise that they perceive colours differently from other people.
Instead, they may simply have difficulty with tasks involving colour identification.
This can become noticeable when using:

• Colour-coded learning materials

• Maps

• Charts

• Graphs

• Art materials

• Coloured instructions

Teachers and parents can often help by ensuring that important information is not communicated using colour alone.
Labels, patterns, symbols and written descriptions can provide additional cues.
Colour-filtering lenses should not replace appropriate educational support or accommodations.
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Colour Vision Deficiency and Career Requirements
Certain occupations have specific colour-vision requirements for safety or operational reasons.
If you are considering a career with a formal colour-vision standard, it is important to understand that wearing colour-enhancing or filtered lenses does not necessarily mean you will meet that occupational standard.
Testing requirements vary between professions and organisations.
You should therefore check the official requirements of the relevant employer, licensing authority or professional organisation.
A colour-filtering lens should never be used to misrepresent colour-vision ability during a test where filters are not permitted.
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Inherited and Acquired Colour Vision Deficiency
Many colour vision deficiencies are inherited and remain relatively stable throughout life.
However, changes in colour perception can sometimes also be acquired later in life.
If you notice a new or unexplained change in colour vision, particularly if one eye is affected differently from the other, appropriate professional eye or medical assessment is important.
A sudden change should not simply be assumed to be inherited colour vision deficiency.
 

 

Allen — Founder & Optician at Eye Zen Optical

Allen has worked in opticianry since 2005 and founded Eye Zen Optical in Singapore in 2022. His work focuses on personalised spectacle solutions, including complex spectacle requirements, prism-related prescriptions and progressive-lens difficulties.

Learn more about Allen →

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Frequently Asked Questions
Is colour vision deficiency the same as colour blindness?
The terms are commonly used interchangeably, but most people with colour vision deficiency are not completely unable to see colour.
They usually have difficulty distinguishing particular colours.
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Can colour vision deficiency be cured with glasses?
No.
Spectacle lenses do not cure the underlying colour vision deficiency.
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Can special lenses help with colour vision deficiency?
Certain tinted or colour-filtering lenses may improve the contrast between particular colours for some individuals, making them easier to distinguish.
The response varies according to the person and type of deficiency.
​
Do colour-enhancing lenses restore normal colour vision?
No.
They alter the appearance and contrast of colours but do not recreate typical colour perception.
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How do colour-filtering lenses work?
The filters selectively alter the wavelengths of light reaching the eye.
This can change the relative contrast or brightness between certain colours, potentially making them easier to differentiate.
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Will the same colour lens work for everyone?
No.
Different people can have different types and degrees of colour vision deficiency.
The response to a particular filter can therefore vary considerably.
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Can colour-filtering lenses help red-green colour deficiency?
Certain filters may improve differentiation between particular colours for some people with red-green colour vision deficiency.
This does not mean the underlying deficiency has been corrected or cured.
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Can colour lenses cure complete colour blindness?
No.
Colour-filtering lenses cannot restore normal colour vision where normal colour perception is absent.
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Can I use colour-enhancing lenses for an occupational colour vision test?
That depends on the rules of the particular test or occupation.
Many occupational standards specify how colour vision must be tested and may not permit filtered lenses.
Always follow the requirements of the relevant authority.
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Should a sudden change in colour vision be checked?
Yes.
New or unexplained changes in colour perception should receive appropriate professional assessment, particularly if the change occurs in only one eye or is associated with other visual symptoms.
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Personalised Colour Vision Solutions in Singapore
If you have a colour vision deficiency and find particular colours difficult to distinguish, specially selected colour-filtering lenses may provide useful assistance in certain situations.
 
At Eye Zen Optical, our approach is personalised.
We consider:
your colour vision difficulty + the colours affected + different filter options + your visual task + your individual response
to determine whether a specialised lens provides a meaningful improvement in colour differentiation.
 
We do not claim to cure colour blindness or restore normal colour vision.
Instead, our aim is to determine whether an appropriate optical filter can help you differentiate certain colours more effectively for your individual needs.
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Eye Zen Optical
71 Kallang Bahru #01-529D
Singapore 330071
WhatsApp / Call: +65 8048 8379
Book a consultation with Eye Zen Optical to discuss your visual concerns.