Understanding the differences between color blindness tests helps you choose the right one for your needs—whether you're screening for a deficiency, diagnosing a specific type, or determining severity for occupational requirements. Each test has strengths and limitations that make it suitable for different purposes.
Overview: Types of Color Blindness Tests
Color blindness tests generally fall into three categories: screening tests, classification tests, and quantitative tests. Here's what each type accomplishes:
Screening Tests
Quick pass/fail assessment. Identifies if color vision deficiency exists.
Examples: Ishihara, online tests
Classification Tests
Identifies the specific type of CVD (protan, deutan, tritan).
Examples: Farnsworth D-15, HRR
Quantitative Tests
Measures exact severity and defines anomaly type precisely.
Examples: Anomaloscope, Farnsworth-Munsell 100
Ishihara Test: The Most Common Screening Tool
The Ishihara test is what most people picture when they think of color blindness testing—those circular plates with colored dots hiding numbers or patterns. Developed in 1917 by Dr. Shinobu Ishihara, it remains the most widely used screening test today.
Ishihara Test Details
What It Tests
- • Red-green color blindness (protan and deutan)
- • Quick screening only—not detailed diagnosis
- • Does NOT test for blue-yellow (tritan) defects
Format
- • 38 plates in full version (14-24 in shortened versions)
- • Numbers hidden in colored dot patterns
- • Takes about 5 minutes
Strengths
- • Quick and easy to administer
- • High sensitivity for red-green CVD
- • Widely available and well-understood
- • Low cost for physical plates
Limitations
- • Cannot diagnose specific type (protan vs deutan)
- • Cannot measure severity
- • Misses blue-yellow defects entirely
- • Sensitive to lighting conditions
Try our online Ishihara test for a quick screening—but remember that online tests can't fully replace professional clinical testing.
Farnsworth D-15 Test: Type Classification
The Farnsworth D-15 goes beyond simple screening to classify the type of color blindness. Instead of reading numbers, you arrange 15 colored caps in order of hue.
Farnsworth D-15 Details
What It Tests
- • All three types: protan, deutan, and tritan
- • Distinguishes between types based on error patterns
- • Indicates severity (mild/moderate/severe)
Format
- • 15 color caps plus one reference cap
- • Arrangement task—put in hue order
- • Error pattern reveals CVD type
The D-15 is particularly useful for occupational assessment because it shows whether a color vision deficiency is severe enough to impact specific job tasks. Mild defects produce few or no errors on this test.
Farnsworth-Munsell 100 Hue Test: Detailed Severity Measurement
The FM 100 Hue test is the more comprehensive version of the D-15, using 85 color caps (despite the name) to measure color discrimination with high precision.
FM 100 Hue Details
What It Tests
- • Fine color discrimination across entire spectrum
- • Precise severity scoring (Total Error Score)
- • Identifies specific confusion areas
Format
- • 85 colored caps in 4 trays
- • Takes 15-20 minutes
- • Requires careful administration
This test is often used in research settings and for detailed clinical diagnosis. It's too time-consuming for routine screening but provides the most detailed picture of color discrimination ability.
Anomaloscope: The Gold Standard
The anomaloscope is considered the definitive test for red-green color blindness. It uses light mixing rather than pigments, eliminating variables like lighting and fading that affect other tests.
How the Anomaloscope Works
You look through an eyepiece at a split field: one half shows a pure yellow light, the other half shows a mixture of red and green light. Your task is to adjust the red-green mixture until it matches the yellow.
- • Normal vision: Matches at a specific red-green ratio
- • Anomalous trichromacy: Matches at different ratios (shifted midpoint)
- • Dichromacy: Accepts a wide range of ratios as matching
The anomaloscope definitively distinguishes between protan and deutan defects and measures severity precisely. However, the equipment is expensive and typically only found in specialized clinics and research facilities.
Hardy-Rand-Rittler (HRR) Test
The HRR test uses pseudoisochromatic plates (like Ishihara) but tests for all three types of color blindness, including blue-yellow defects.
Advantages over Ishihara
- • Tests red-green AND blue-yellow
- • Indicates severity level
- • Uses symbols, not numbers (works for children)
- • Better classification of CVD type
Limitations
- • Less sensitive than Ishihara for screening
- • More expensive than Ishihara plates
- • Less widely available
- • Still affected by lighting conditions
Online Tests: Pros and Cons
Online color blindness tests, like those we offer here at RGBlind, serve an important purpose—but understanding their limitations is essential:
What Online Tests Do Well
- • Quick initial screening anywhere
- • Free and immediately accessible
- • Raise awareness of potential CVD
- • Help users understand their color perception
- • Encourage professional follow-up
Inherent Limitations
- • Monitor calibration varies significantly
- • Ambient lighting affects results
- • Cannot replace clinical diagnosis
- • Not valid for occupational certification
- • Color accuracy depends on hardware
Which Test Should You Take?
For initial screening:
Start with an Ishihara test or our color perception test. Quick, free, and gives you a baseline understanding.
For occupational requirements:
You'll need professional clinical testing—typically Ishihara followed by D-15 or anomaloscope, depending on the job requirements.
For detailed diagnosis:
See an ophthalmologist or optometrist who can administer anomaloscope and FM 100 Hue tests if needed.
Start With a Screening Test
Take our free online tests to get an initial understanding of your color vision. For formal diagnosis, follow up with a vision professional.
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