# Color Blind Test A free 12-plate Ishihara-style screening for red–green color vision deficiency. Everything runs in your browser — no signup, no upload, no tracking. What **number** do you see in the plate above? Tap *Nothing* if it's blank. This is a screening tool, not a medical diagnosis. Screen brightness, calibration, ambient light, and lens color all affect the result. See an eye-care professional for a formal assessment. ## About this test The Ishihara test — designed by Dr Shinobu Ishihara in 1917 — uses plates of coloured dots that form a number visible to people with typical color vision. People with red–green color vision deficiency see a different number, or nothing at all. ### What it screens for - **Protanopia / protanomaly** — reduced or missing sensitivity to red light. - **Deuteranopia / deuteranomaly** — reduced or missing sensitivity to green light. - Together these account for the vast majority of color vision deficiencies (~8% of men, ~0.5% of women). ### What it doesn't screen for - **Tritanopia** (blue–yellow deficiency) — very rare, and Ishihara plates are not designed to detect it. - **Achromatopsia** (total color blindness) — requires clinical testing. - Subtle acuity or contrast issues unrelated to color. ### For the most reliable read - Use a well-calibrated screen at full brightness. - View in a normally-lit room — not direct sunlight or a fully dark room. - Don't wear tinted glasses. - Answer with your first instinct; don't strain. ## Understanding colour vision deficiency Colour vision deficiency — commonly called colour blindness — means seeing colours differently from most people, which usually makes it hard to tell certain colours apart.[1](#cbt-ref-1) It is far more common than most people assume: according to the U.S. National Eye Institute, red–green colour blindness affects roughly **8% of men and 0.5% of women** of Northern European ancestry.[2](#cbt-ref-2) The vast majority of cases are inherited and present from birth, though colour vision can also change later in life through eye disease, brain or nervous-system conditions, or certain medicines.[3](#cbt-ref-3) ### Why it mostly affects men The genes for the most common, red–green form are carried on the X chromosome and are recessive. Males have a single X chromosome, so one affected copy is enough to produce the deficiency; females have two X chromosomes, so both copies must carry the gene — which is far less likely.[3](#cbt-ref-3) That single difference in inheritance is why colour blindness shows up in men many times more often than in women. ### The main types The retina relies on three kinds of colour-sensing cone cell, tuned to long (red), medium (green), and short (blue) wavelengths. Colour vision deficiency happens when one type is missing or shifted in sensitivity:[4](#cbt-ref-4) - **Red–green (protan and deutan)** — by far the most common group. Protanomaly and protanopia affect the red cones; deuteranomaly and deuteranopia affect the green cones. Deuteranomaly is the single most common type. - **Blue–yellow (tritan)** — much rarer, affecting the blue cones, and it occurs about equally in men and women. - **Complete colour blindness (monochromacy / achromatopsia)** — seeing no colour at all, which is rare and requires clinical testing. ### How the Ishihara test works The plates on this page follow the method published by Dr Shinobu Ishihara, a professor at the University of Tokyo, in 1917.[5](#cbt-ref-5) Each plate is *pseudoisochromatic*: dots of varying size and brightness are coloured so that a figure — usually a number — stands out to people with typical colour vision but blends into the background for someone with a red–green deficiency (or the reverse). Because it is quick, needs no equipment beyond the printed or displayed plates, and is easy to score, the Ishihara test became a widely adopted international screening standard and remains one of the most recognised colour vision tests today.[5](#cbt-ref-5) ### A screening tool, not a diagnosis An online test like this one is a useful first check, but it cannot replace a professional eye exam. Screen calibration, brightness, ambient light, and even the device's colour profile all affect the result, and no self-test can grade the *severity* of a deficiency or rule out the rarer forms. There is currently no cure for inherited colour vision deficiency, though most people adapt well and may not need any treatment.[4](#cbt-ref-4) If a result matters for a career with colour-critical requirements — aviation, rail, electrical work, or the armed forces, for example — or if colour vision seems to have changed recently, see an optometrist or ophthalmologist for formal testing.[4](#cbt-ref-4) ### Sources 1. National Eye Institute (NIH). [Color Blindness](https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/color-blindness). 2. National Eye Institute (NIH). [Types of Color Vision Deficiency](https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/color-blindness/types-color-vision-deficiency). 3. National Eye Institute (NIH). [Causes of Color Vision Deficiency](https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/color-blindness/causes-color-vision-deficiency). 4. NHS. [Colour vision deficiency (colour blindness)](https://www.nhs.uk/conditions/colour-vision-deficiency/). 5. Wikipedia. [Ishihara test](https://en.wikipedia.org/wiki/Ishihara_test). ## Related tools --- *Source: [ocxly.com/color-blind-test.html](https://ocxly.com/color-blind-test.html) — OCXLY, free 100% client-side privacy-first tools. Take a free interactive Ishihara color blind test online. 12 plates screen for red-green color vision deficiency (protanopia, deuteranopia) — instant results, no signup, works in your browser.*