What Is Color Blindness?

Color blindness (color vision deficiency or CVD) is difficulty distinguishing certain colors due to absent or malfunctioning cone cells in the eye. The term "blindness" is misleading — most people with color vision deficiency struggle to differentiate certain color pairs rather than seeing a fully colorless world.

Approximately 300 million people worldwide live with color vision deficiency. It affects 8% of men and 0.5% of women. Despite being this common, many people don't realize it until adulthood.

Types of Color Blindness

Red-Green Color Blindness (Most Common)

Two subtypes exist:

  • Deuteranopia / Deuteranomaly (Green deficiency): Caused by absent or reduced M-cones. Green hues appear yellowish or beige. This is the most common form of red-green color blindness.
  • Protanopia / Protanomaly (Red deficiency): Caused by absent or reduced L-cones. Red tones may look dark brown or black. Distinguishing traffic lights and stop signs can become genuinely difficult.

Blue-Yellow Color Blindness (Tritanopia)

Caused by absent S-cones. Very rare. Blue and green, as well as yellow and pink, may be confused. It affects men and women equally — unlike red-green CVD, it is not X-linked.

Total Color Blindness (Achromatopsia)

All cone cells are non-functional. Extremely rare (0.003%). The person perceives the world only in shades of grey, and typically also suffers severe light sensitivity (photophobia).

Symptoms: How Do You Know If You Have Color Blindness?

The most commonly reported symptoms include:

  • Confusing red with green, or blue with yellow
  • Colors appearing dull, washed-out, or "dirty"
  • Increased difficulty distinguishing colors in low light
  • Struggling to match clothing colors correctly
  • Difficulty judging the ripeness of fruit or freshness of food by color
  • Relying on position (top/middle/bottom) rather than color to read traffic lights

If you recognize several of these symptoms, we strongly recommend a professional eye examination. A browser-based Ishihara-style test like the one on Hesaplabs can give you a meaningful first indication.

Causes: Why Does Color Blindness Occur?

Inherited Color Blindness

Red-green color blindness results from a recessive gene mutation on the X chromosome. Since males have only one X chromosome (XY), a single copy of the affected gene is sufficient to cause the condition. Females have two X chromosomes (XX), so both copies must be affected — making CVD far less common in women. Sons of carrier mothers have a 50% chance of being color blind.

Acquired Color Blindness

Color vision deficiency can also develop later in life:

  • Eye diseases: Glaucoma, macular degeneration, diabetic retinopathy
  • Optic nerve damage: Multiple sclerosis or physical trauma
  • Drug side effects: Chloroquine, digitalis, ethambutol can impair color perception
  • Chemical exposure: Long-term exposure to solvents such as carbon disulfide or styrene
  • Aging: As the lens loses clarity, color discrimination gradually weakens

Impact on Daily Life

Color blindness can complicate many seemingly straightforward situations:

Education and Career

Reading maps, interpreting charts, and understanding color-coded diagrams can be significantly harder. Some professions require normal color vision: pilots, certain naval ranks, electricians (wire color coding), and some medical specialties. Children who are not diagnosed early may be unnecessarily disadvantaged in color-based learning activities.

Safety

Misreading traffic lights, warning signs, or emergency indicators can pose real risks. Individuals with protanopia may perceive red lights as black or very dark — making it hard to detect them quickly.

Technology and Design

For graphic designers, developers, and UX designers, color blindness awareness is a critical professional skill. WCAG (Web Content Accessibility Guidelines) color contrast requirements are partly designed with color vision deficiency users in mind.

What Is the Ishihara Test?

Developed in 1917 by Japanese ophthalmologist Shinobu Ishihara, the Ishihara test is the most widely used method for detecting color vision deficiency. It consists of colored plates in which numbers or shapes are hidden within dot patterns:

  • People with normal color vision read the numbers easily.
  • Individuals with red-green CVD either cannot see the numbers or read them differently.
  • Some plates are designed so that only color-blind individuals can see the hidden figure.

The original Ishihara set contains 38 plates. Clinical examinations typically use 14–24 plates. Browser-based versions may not be as precise as clinical tests due to monitor calibration differences — but they are highly valuable for an initial self-assessment.

Is There a Cure for Color Blindness?

There is currently no definitive cure for inherited color blindness. However, several support options exist:

  • Specially filtered glasses and lenses (e.g., EnChroma): Lenses that filter specific wavelengths have been reported to improve color discrimination for some people with red-green CVD. However, they don't work for everyone and don't provide full normal color vision.
  • Gene therapy research: Studies in animal models have yielded promising results, but clinical application in humans has not yet been established.
  • Digital accessibility tools: Color identification apps and "color-blind friendly" software filters can make everyday digital use easier.

Why Early Diagnosis in Children Matters

When color vision deficiency is identified during preschool or early school years, the educational environment can be properly adapted. Teachers can offer alternatives to color-coded materials, and the child can understand their condition rather than feeling slow or inadequate.

Eye screening programs in schools should include color vision testing. Parents who ensure their children receive proper eye exams make a significant difference in catching this early.

Test Yourself for Free in Your Browser

Hesaplabs's Color Blindness Test lets you take an Ishihara-style test directly in your browser at no cost. The test takes about 3 minutes and screens for the most common types of color vision deficiency: deuteranopia, protanopia, and tritanopia.

Important note: This test is not a medical diagnostic tool. If your results suggest a color vision deficiency, please consult an ophthalmologist for a proper clinical examination.