I have been living with optic neuritis since early January. For those who do not know, optic neuritis is inflammation of the optic nerve. It can cause blurred vision, pain when moving the eye, and in some cases, colour blindness. Colours can look washed out or wrong. Reds and greens can blend together. Blues and yellows can become hard to tell apart.
I am on treatment now. I think it might be working. But I wanted a way to check. Something I could run regularly, in the same conditions, to see if my colour vision was improving or staying the same. So I built Pure Colour Test.
What Pure Colour Test Does
Pure Colour Test is a colour vision screening tool that runs entirely in your browser. It uses Ishihara-style plates: a number is hidden in a field of coloured dots. If you can see the number, you pass that plate. If you cannot, you might have a colour vision deficiency in that part of the spectrum.
The tool tests three different types of colour vision:
Red-Green Plates
These plates have green backgrounds with orange-red numbers. They test for red-green colour deficiency (protanopia and deuteranopia). This is the most common form of colour blindness. People with red-green deficiency often cannot see the number because the orange and green dots look too similar.
Blue-Yellow Plates
These plates have blue backgrounds with yellow numbers. They test for blue-yellow deficiency (tritanopia). This is rarer. People with tritanopia struggle to tell blue from yellow and may see the plate as a uniform field of similar shades.
Monochromacy (Luminance) Plates
These plates are different. They use only grey. The background is mid-grey dots; the number is formed by darker grey dots. There is no colour at all. People with total colour blindness (monochromacy) can still see these, because they rely on brightness, not hue. For everyone else, they act as a control: if you can see the luminance plates but fail the colour plates, that pattern can suggest monochromacy.
How the Test Works
You see eight plates in total: three red-green, three blue-yellow, and two monochromacy. For each plate, you choose the number you see from four options. The correct answer is always one of the choices. At the end, you get a score and a short interpretation. The tool explains whether your results suggest typical colour vision, mild difficulty, possible deficiency, or (if you pass luminance but fail colour) possible monochromacy.
Why I Built It for Myself
I needed a way to track my colour vision over time. Same device. Same screen. Same test. Run it once a week and see if the score changes. If treatment is working, I would hope to see improvement. If not, I would know to talk to my specialist.
I also wanted it to be private. No data sent. No account. No tracking. Everything runs in the browser. Your results never leave your device. That is how we build things at Pure Contrast Tools.
For Everyone Else
If you have ever wondered about your colour vision, or if you have a condition that affects it, Pure Colour Test is there. It is not a medical diagnosis. See an optometrist for proper testing. But for a quick, private, repeatable check, it does the job.