Colour vision deficiency (CVD), or colour blindness, affects many people worldwide. Some may not even realise they have it until they take a test. While professional testing is the gold standard, online tests provide a quick and accessible way to check for CVD.
These tests use specific patterns and numbers to assess how well a person can distinguish different colours. They are easy to find and take just a few minutes. But how reliable are they? And can they really determine if someone has perfect colour vision?
This guide explores how to take a colour blind test, what the results mean and its limitations.
What is a Colour Blind Test?
A colour blind test helps identify colour vision deficiency. It checks whether someone struggles to see certain colours or mixes them up. The most common type of CVD affects red-green perception, making it hard to distinguish shades of these colours. Other types, like blue-yellow deficiency, are rarer.
Types of Colour Blind Tests
- Ishihara Test – The most widely used test. It consists of coloured dot patterns with numbers hidden inside. Those with red-green colour blindness may not see the numbers.
- Farnsworth D-15 Test – This requires arranging coloured tiles in order of shade. It helps determine the severity of CVD.
- Anomaloscope – A more detailed test where users adjust light intensities to match colours. This is typically done in professional settings.
Online versions of these tests replicate the Ishihara and Farnsworth tests. While they don’t offer medical precision, they provide a helpful first step in identifying potential colour vision issues.
How to Take an Online Colour Blind Test
Taking an online colour blind test is simple and only takes a few minutes. Here’s how to do it:
Step 1: Choose a Reliable Test
It’s best to pick one from a reputable test provider. Some tests are more accurate than others, so reading reviews can help.
Step 2: Adjust Your Screen Settings
A test’s accuracy depends on the device used. Ensure:
- Brightness is set to a comfortable level – Too much or too little light can distort colours.
- Colour settings are at default – Avoid any display filters or modes that enhance colours.
- The test is taken on a high-quality screen – Older screens may not display colours accurately.
Step 3: Sit in Proper Lighting
Taking the test in natural light or under neutral white lighting prevents colour distortion. Avoid dim or overly bright rooms.
Step 4: Follow the Instructions
Most tests display a series of images with numbers or patterns inside coloured dots. The task is to identify what’s inside. Some may also involve arranging colours in order.
Step 5: Review Your Results
After completing the test, results appear instantly. They usually indicate if colour blindness is present and which type it might be.
Tip: If results are unclear or inconsistent, taking the test on another device can help.
Understanding Your Results
Test results generally fall into three categories:
- Normal Colour Vision – The user correctly identifies all numbers and patterns, indicating no colour vision deficiency.
- Mild to Moderate Colour Blindness – Some numbers or patterns are difficult to see, suggesting possible CVD.
- Severe Colour Blindness – Most numbers or patterns are invisible, pointing to a more significant deficiency.
Can a Perfect Score Be Used as Proof of Normal Colour Vision?
Yes and no. A perfect score can indicate good colour vision, but it’s not absolute proof. Employers or medical professionals may still require clinical testing for formal verification.
Accuracy of Online Tests
While online tests are convenient, their accuracy depends on several factors:
1. Display Settings & Device Quality
Not all screens display colours the same way. Older screens, poor resolution or incorrect settings can affect test accuracy.
2. Ambient Lighting
Too much light or a dark room can distort colours, leading to incorrect results.
3. Individual Perception
Colour perception varies from person to person. Some may struggle due to eye strain, tiredness or environmental factors at the time of the test.
Despite these challenges, online tests are still useful as a preliminary assessment.
Limitations of Online Testing
Online tests are helpful, but they have their flaws. Here’s why they shouldn’t replace professional testing:
1. Lack of Medical Precision
A professional eye exam uses advanced tools and precise colour calibration. Online tests lack this accuracy.
2. No Diagnosis or Severity Assessment
Online tests only indicate a possible deficiency. They cannot measure the severity of colour blindness.
3. Screen & Lighting Issues
As mentioned earlier, display variations can affect how colours appear. A calibrated medical device provides more reliable results than a home computer or phone screen.
4. No Confirmation from an Eye Specialist
Only an optometrist or ophthalmologist can confirm colour blindness and provide guidance on coping strategies or career limitations.
The Role of Online Tests in Professional Settings
Certain jobs require perfect colour vision, such as:
- Pilots
- Electricians
- Graphic designers
- Train drivers
- Military personnel
An online test can be a quick way to check if someone might meet these requirements. However, it’s only a preliminary step. Many professions demand a certified test for official documentation.
For example, an aspiring pilot may use an online test as a first check. But to qualify, they must pass an aviation-approved colour vision exam.
Similarly, some employers may accept an online test result as informal proof of good colour vision. But, official verification from a medical professional is always preferred.
Conclusion
Online tests offer a fast, accessible way to check for CVD. They are easy to use and can help identify potential colour vision issues. However, they come with limitations. Screen settings, lighting and device quality can impact results.
A perfect score on an online test can be reassuring, but it’s not a substitute for a medical examination. For career or medical reasons, a professional test remains essential.
In short, online tests are great for initial screening but should not be relied on for a final diagnosis. If there’s any doubt about colour vision, visiting an eye specialist is the best course of action.
Smith