Color Blindness — What You Probably Don't Know (8% of Men Are Affected)

About 8% of men and 0.5% of women worldwide have some form of color vision deficiency. That is roughly 1 in 12 men — meaning if you have twelve male colleagues, statistically one of them sees color differently from everyone else. And many of them don't know it.

Color blindness is commonly misunderstood. The word "blindness" implies seeing in grayscale, like an old movie. For most people with color vision deficiency, that is not what happens at all. They see color — just not the same distinctions everyone else does. This matters for how we design things, how we communicate, and sometimes practically for everyday life.

What color blindness actually looks like

Most color blindness is not black and white vision. The most common types affect the ability to distinguish certain color pairs:

Red-green color blindness (the most common type)

This affects about 8% of men. People with this condition may have difficulty distinguishing reds from greens, or both from browns. A traffic light is still visible — but the specific hue of the red and green may look similar, especially in peripheral vision or in certain lighting. Red strawberries on a green bush might blend together.

Blue-yellow color blindness (deuteranopia and tritanopia)

Less common. Blues and yellows may be harder to distinguish from each other or from certain greens and reds. This affects both men and women at similar rates, unlike red-green deficiency.

Monochromacy (complete color blindness)

This is the kind people imagine when they hear "color blind" — seeing only shades of gray. It is extremely rare, affecting about 1 in 30,000 people. People with this condition often have other visual impairments as well.

Why so many people go undiagnosed

Color vision deficiency is present from birth and doesn't change. But the diagnosis often happens surprisingly late in life — sometimes not until adulthood. There are a few reasons for this:

It develops gradually in awareness, not vision. Someone who has always seen colors this way doesn't know their perception is different. If you have always called a particular shade "green" and people around you agree it's green, you don't know you're seeing it differently.
School screenings are inconsistent. Many schools do basic color vision tests, but not all, and the tests can be easy to partially pass through other cues.
People adapt without realizing it. Color blind individuals often develop strategies — remembering which button is which by position, reading labels instead of relying on color coding — without consciously thinking of these as adaptations.

Practical implications

Driving

Most countries allow people with color vision deficiency to drive. Traffic lights are typically identified by position (top, middle, bottom) as much as by color. However, some countries do restrict certain commercial driving licenses — particularly for professional drivers of trains or planes, where color-coded signals are safety-critical.

Career restrictions

Certain professions require full color vision: pilots, some military roles, electricians (wire color coding is safety-critical), and in some countries, police officers. If you're considering one of these careers and haven't been tested, it's worth knowing early.

Design and communication

This is where color blindness most commonly affects other people. If you design presentations, data charts, websites, or any visual content, using color alone to convey meaning creates problems for 8% of your male audience. The fix is usually simple: add labels, patterns, or icons alongside color. Never rely on "the red bar is higher than the green bar" as the only way to read a chart.

Design rules for color accessibility

You don't need to eliminate color — just don't rely on it exclusively:

Use labels in addition to color in charts and graphs
Use different line styles (solid, dashed, dotted) for different data series
Ensure text contrast is high enough regardless of color (WCAG recommends 4.5:1 ratio)
Avoid red-on-green or green-on-red color combinations for important information
Test your designs with a color blindness simulator — there are browser extensions that simulate what people with various color deficiencies see

How to test your own color vision

The most commonly used clinical test is the Ishihara plates — a series of circles made of colored dots, with numbers hidden inside that are visible to people with normal color vision but not to those with red-green deficiency. A full Ishihara test has 38 plates and is done by an ophthalmologist or optometrist.

You can get a rough indication with our color blindness self-test. It won't replace a clinical test, but it can tell you whether it's worth getting a proper assessment.