What is a colour blind test?

A colour blind test screens for colour vision deficiency by presenting Ishihara-style plates — circular patterns of coloured dots hiding numbers or shapes. People with certain colour vision deficiencies cannot distinguish the hidden number from the background dots.

Can colour blindness be cured?

There is currently no cure for inherited colour blindness. However, special EnChroma-type glasses and contact lenses can improve colour perception for some types of red-green colour deficiency. They do not restore full normal colour vision.

What types of colour blindness does this test detect?

This test can screen for red-green deficiency (the most common type, affecting 8% of men), blue-yellow deficiency (tritanopia, rarer), and strong total colour blindness. Different plates target different colour channels to help identify which type may be present.

Is an online colour blind test as accurate as a clinical test?

Online tests are screening tools, not clinical diagnoses. Results can be affected by screen colour calibration, ambient lighting, and screen brightness. A confirmed diagnosis requires an optometrist using physical Ishihara plates under controlled lighting conditions.

Can children take a colour blind test?

Yes. Colour vision testing is often recommended around age 4–5 before school entry, as colour deficiency can affect learning. This test uses simple single-digit numbers (1–9) and a 'can't see it' option, making it accessible for older children who can read numbers.

What should I do if I fail the colour blind test?

If this screening suggests a colour vision deficiency, visit an optometrist for a full clinical assessment using professional Ishihara plates. Colour deficiency can affect career paths (aviation, military, some design roles) and it is important to have an official diagnosis on record.

👁️ Colour Blind Test

10 Ishihara-style plates. Can you see every number? Results in under 2 minutes — no signup required.

👁️

Colour Vision Screening

10 plates · ~2 minutes · Works best in a normally lit room
Maximise screen brightness and sit about 35cm from the screen.

⚠️ Important: This is a screening tool, not a clinical diagnosis. See an optometrist if you suspect colour vision deficiency.

Colour Blindness Prevalence

Type	Men	Women
Red-green	8%	0.5%
Blue-yellow	0.01%	0.01%
Total (achromatopsia)	0.003%

X-linked inheritance explains why colour blindness is far more common in men than women.

How Ishihara Colour Blind Tests Work

Ishihara plates were developed by Dr Shinobu Ishihara in 1917 and remain the gold standard for screening red-green colour vision deficiency. Each plate is a circle filled with dots of varying size and colour. For people with normal colour vision, the arrangement of dots forms a visible number. For people with red-green deficiency, the dots appear as a uniform field with no distinguishable number.

The dots are carefully chosen so that the number dots and background dots differ only in hue (red vs green), not in brightness. This means someone cannot "see through" the test by perceiving brightness differences alone — only genuine colour discrimination reveals the number. MindSnap's plates use a canvas-based generative algorithm that mirrors this principle: dots are placed in a circular field with controlled size variance and colour clustering around the target shape.

Types of Colour Vision Deficiency Explained

Red-green colour blindness is the umbrella term for two distinct conditions: deuteranopia (reduced sensitivity to green light, ~5% of men) and protanopia (reduced sensitivity to red light, ~1% of men). Together they affect roughly 8% of men and 0.5% of women — making them the most common form of colour vision deficiency by a large margin.

Blue-yellow colour blindness (tritanopia) is far rarer, affecting approximately 1 in 10,000 people equally between men and women, because the relevant gene is on chromosome 7 rather than the X chromosome. Total colour blindness (achromatopsia) — seeing only in greyscale — is extremely rare and almost always accompanied by other visual issues including severe light sensitivity and reduced visual acuity.

Occupations Affected by Colour Vision Deficiency

Colour vision requirements vary significantly by profession. Commercial aviation authorities (including the FAA and EASA) require pilots to pass colour vision tests as part of medical certification — though modern colour-safe instrument design has reduced the practical impact. Electrical work and electronics require distinguishing colour-coded wires (red, black, blue, yellow, green). Certain roles in the military, law enforcement, and maritime navigation also have colour vision requirements.

In creative fields, graphic designers, photographers, and UX designers with colour deficiency can work effectively with assistive tools and deliberate workflow adjustments — many famous artists are believed to have had some form of colour vision deficiency. The most important step is knowing your specific deficiency type so you can adapt accordingly.

Frequently Asked Questions

A colour blind test screens for colour vision deficiency using Ishihara-style plates — circular patterns of coloured dots hiding numbers. People with certain colour vision deficiencies cannot distinguish the hidden number from the background.

Approximately 8% of men and 0.5% of women have some form of colour vision deficiency. Red-green colour blindness is by far the most common type, caused by a mutation on the X chromosome.

There is no cure for inherited colour blindness. Special glasses (like EnChroma) can improve colour perception for some red-green deficiency types, but do not restore full normal colour vision.

"Colour blind" is a common misnomer. Most affected people can still see colours — they just have difficulty distinguishing certain pairs (typically red-green). True total colour blindness (achromatopsia) is extremely rare.

This test screens for red-green deficiency (most common, affecting ~8% of men), blue-yellow deficiency (tritanopia), and indicators of total colour blindness. Different plates isolate different colour channels.

Online tests are screening tools only. Results depend on screen calibration and lighting. A confirmed diagnosis requires an optometrist using physical Ishihara plates under controlled lighting.

Yes — testing is often recommended at age 4–5 before school. This test uses simple single digits and a "can't see it" option to make it accessible for older children who can read numbers.

Visit an optometrist for a full clinical assessment. Colour deficiency affects certain careers (aviation, military, some design roles) and an official diagnosis is important to have on record.