Does this tool diagnose color blindness?

No. This is an educational reference only. A formal diagnosis requires an Ishihara test or other clinical assessment performed by an eye-care professional.

What is the most common type of color vision deficiency?

Deuteranopia and its milder form deuteranomaly (reduced green sensitivity) are the most common, affecting roughly 5% of males worldwide.

Can women be color blind?

Yes, though it is less frequent. Red-green color blindness affects about 8% of males and 0.5% of females of Northern European descent.

What is an Ishihara plate?

An Ishihara plate is a circle of colored dots containing a hidden number or shape. People with color vision deficiencies see different numbers — or none — compared to those with typical color vision. The full test has 38 plates and is administered by a clinician.

Is achromatopsia the same as complete color blindness?

Achromatopsia (rod monochromacy) is the rarest and most severe form: affected individuals see the world in shades of gray. It also involves light sensitivity and reduced visual acuity.

Color Vision Deficiency Helper

Name: Color Vision Deficiency Helper
Availability: InStock
Author: Nham Vu

Explore the four main types of color vision deficiency, affected color pairs, and an Ishihara-style plate legend — for education, not diagnosis.

Educational reference only. This page describes color vision deficiencies; it does not diagnose them. Consult an eye-care professional for a clinical Ishihara or anomaloscope test.

Deficiency Types

Missing / defective cone: Long-wavelength (L) cone — red-sensitive
Inheritance & prevalence: X-linked recessive; affects ~1% of males

How colors appear

Reds appear very dark or black; confusion between red, black, and dark brown; green and orange look similar; traffic light red can look off.

Commonly confused color pairs

Color A	Color B	Perceived as similar
Red	Black	Often indistinguishable
Red	Dark brown	Often indistinguishable
Green	Orange	Often indistinguishable
Blue	Purple	Often indistinguishable
Pink	Gray	Often indistinguishable

Note: Protanomaly is the partial form: L-cones are present but shifted in sensitivity, causing milder red-green confusion.

Missing / defective cone: Medium-wavelength (M) cone — green-sensitive
Inheritance & prevalence: X-linked recessive; affects ~1% of males (anomaly ~5%)

How colors appear

Greens and reds look similar; both may appear as yellow or brown. Most common form of red-green color blindness.

Commonly confused color pairs

Color A	Color B	Perceived as similar
Red	Green	Often indistinguishable
Red	Yellow	Often indistinguishable
Green	Brown	Often indistinguishable
Blue	Purple	Often indistinguishable
Orange	Olive	Often indistinguishable

Note: Deuteranomaly is the most prevalent color vision deficiency overall. Affected individuals often adapt well and may not notice mild cases.

Missing / defective cone: Short-wavelength (S) cone — blue-sensitive
Inheritance & prevalence: Autosomal dominant; rare, affecting <0.01% of people

How colors appear

Blues and greens look alike; yellow and pink may appear similar; blue-yellow axis is lost rather than red-green.

Commonly confused color pairs

Color A	Color B	Perceived as similar
Blue	Green	Often indistinguishable
Yellow	Pink	Often indistinguishable
Purple	Red	Often indistinguishable
Blue	Gray	Often indistinguishable
Light green	White	Often indistinguishable

Note: Tritanomaly (partial S-cone loss) is slightly more common than tritanopia. Unlike red-green types, it affects males and females equally.

Missing / defective cone: All three cone types absent or non-functional (rod monochromacy)
Inheritance & prevalence: Autosomal recessive; extremely rare (~1 in 30,000)

How colors appear

Complete absence of color perception — world appears in shades of gray. Often accompanied by nystagmus, photophobia, and reduced visual acuity (~20/200).

Commonly confused color pairs

Color A	Color B	Perceived as similar
Any color	Any other color	Often indistinguishable

Note: Cerebral achromatopsia is a distinct acquired condition caused by brain lesions, not a cone defect. Blue cone monochromacy is a separate rare variant with residual S-cone function.

Ishihara Plate Legend

The standard Ishihara test has 38 plates. Each plate type reveals different information about color vision. Below is an educational summary of plate categories — the actual plates must be administered clinically.

Introductory (Plate 1)

Everyone with normal or deficient color vision sees the same number. Confirms the person understands the task.

All responses expected: "12"

Transformation plates

People with typical vision see one number; those with red-green deficiency see a different number.

Normal: one number. Color-deficient: different number.

Disappearing plates

People with typical vision see a number; those with color deficiency see nothing.

Normal: number visible. Color-deficient: blank.

Hidden digit plates

People with color deficiency see a number that is invisible to those with typical color vision.

Color-deficient: number visible. Normal: blank.

Classification plates

Distinguish protanopia from deuteranopia by which of two numbers the person reads.

Protanope vs. deuteranope: different numbers.

Tracing plates

Used with young children who cannot read numbers. A colored path is traced instead.

Deficient: cannot trace the colored path.

Quick Comparison

Type	Cone affected	Axis lost	Prevalence (males)
Protanopia	L (red)	Red-green	~1%
Deuteranopia	M (green)	Red-green	~1% (anomaly ~5%)
Tritanopia	S (blue)	Blue-yellow	<0.01%
Achromatopsia	All cones	All color	~0.003%

Summary

Explore the four main types of color vision deficiency, affected color pairs, and an Ishihara-style plate legend — for education, not diagnosis.

How it works

The tool displays structured educational data about each deficiency type.
Affected color pairs are derived from standard color-vision research literature.
The Ishihara plate legend describes plate categories used in the 38-plate clinical test.

Use cases

Learning what each color vision deficiency means before an ophthalmology appointment.
Designers checking which color pairs to avoid for color-blind users.
Educators explaining color vision to students or patients.
People who suspect color vision differences wanting a plain-language reference.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu