What is colour blindness?
Colour blindness affects how a person sees and tells the difference between certain colours. It does not mean total loss of sight. In most cases, vision stays sharp but colour signals do not work as expected.
How normal colour vision works
The eye uses light-sensitive cells called cones. These cones respond to red, green and blue light. The brain combines these signals to form colour. When cones work well, colours appear clear and distinct.
What colour blindness means
Colour blindness happens when one or more cone types do not work fully. This changes how colours appear. Some colours may look the same or washed out. The condition can be mild or more noticeable.
Common types of colour blindness
Red-green colour blindness is the most common type. Blue-yellow colour blindness is less common. Total colour vision loss is rare. Each type affects daily tasks in different ways.
How common is colour blindness?
Colour blindness affects more men than women. It often runs in families. Many people do not realise they have it until they are tested.
What colour blind tests check
Colour blind tests assess how well the eyes and brain recognise colour differences. They form a basic but important part of eye care.
How colour blind tests work
A colour blind test uses patterns made of dots or shapes in different colours. The person identifies numbers or symbols. The answers show how colour signals are processed.
What results can show
Results can show the type and level of colour vision loss. They help eye professionals understand whether colour changes are stable or getting worse.
Limits of colour blind tests
These tests do not explain the full cause on their own. They cannot diagnose all eye diseases. Further checks are often needed.
Why colour blind tests matter for eye health
Changes in colour vision can reflect wider problems in the eye or nervous system. Testing helps spot issues that may not yet affect sharpness of sight.
Early signs of eye disease
Some eye diseases affect colour vision first. Conditions involving the retina or optic nerve may reduce colour clarity before other symptoms appear.
Monitoring changes in vision
Repeat testing helps track changes over time. A decline in colour vision can signal damage or disease progression.
Detecting damage to the optic nerve
The optic nerve carries visual signals to the brain. Damage can alter colour perception. Colour testing can support early detection.
Identifying retinal conditions
The retina plays a key role in colour vision. Disease or injury can affect how colours are seen. Testing supports wider retinal checks.
Supporting accurate diagnosis
Colour vision results add context to other eye tests. This helps eye professionals reach clearer and safer conclusions.
Who should have colour blind tests
Colour blind tests support eye care across all age groups. Some people benefit more due to risk, work, or changes in vision.
Children and early screening
Testing in childhood helps identify colour vision issues early. This supports learning, safety, and classroom tasks that rely on colour.
Adults with vision changes
Adults should consider testing if colours appear dull or unclear. Sudden changes can point to eye or nerve problems that need review.
Workers in safety-critical roles
Some jobs rely on colour signals for safe work. Testing helps confirm that workers can meet visual demands and reduce risk.
People with a family history
Colour blindness often runs in families. Testing helps confirm whether colour vision changes are inherited or linked to eye health.
When and how often to test
The timing of colour blind tests depends on age, health, and risk factors. They are often part of wider eye checks.
Routine eye checks
Colour testing may be included in regular eye exams. This supports a complete review of visual function.
Testing after illness or injury
Eye disease, head injury, or nerve damage can affect colour vision. Testing helps assess impact and recovery.
Ongoing monitoring
Repeat tests help track changes over time. This supports early action if vision declines.
What happens after a colour blind test
Test results guide next steps in care. These steps depend on the cause and level of colour vision loss.
Understanding the results
Eye professionals explain what the results mean. They confirm whether colour vision is stable or changing.
Managing colour vision problems
There is no cure for inherited colour blindness. Adjustments, tools, and workplace support can reduce impact.
When a referral is needed
Referral may follow if results suggest disease or nerve damage. Further tests help confirm the diagnosis and treatment.
Seeing the full picture
Colour blind tests do more than identify colour vision differences. They support early detection of eye disease, guide monitoring, and protect long-term eye health. Regular testing helps ensure that changes in colour vision are not missed.
