Red-Green Color Blind Test
Detect Protanopia (red blindness) and Deuteranopia (green blindness) with our specialized red-green color vision test.
Red-Green Color Blind Test
This test uses C-shaped Landolt rings to screen for red-green color blindness. Find the gap in the colored ring and click directly on it.
- •Look at the colored circle and find the gap (opening)
- •Click directly on the gap in the ring
- •If you cannot see the gap, click "I Can't See"
Understanding Red-Green Color Blindness
Red-green color vision deficiency is the most prevalent form of color blindness, representing roughly 95% of all inherited cases. It occurs when the cone cells responsible for perceiving red or green wavelengths of light are either absent or function abnormally.
Globally, about 8% of males and 0.5% of females experience some degree of red-green deficiency. The condition is inherited through the X chromosome, which explains the significant gender disparity — males carry only one X chromosome, so a single affected gene results in color blindness.
Protan Deficiency
Caused by reduced sensitivity or absence of long-wavelength (L) cones. Protanopia means complete absence of red cones, while Protanomaly means reduced red sensitivity. Reds appear darker and may be confused with black, brown, or dark green.
Deutan Deficiency
Caused by reduced sensitivity or absence of medium-wavelength (M) cones. Deuteranopia means complete absence of green cones, while Deuteranomaly means reduced green sensitivity. Greens tend to blend with reds, yellows, and browns.
Prevalence Breakdown (Males)
How to Take the Test
1. Start the Test
Click "Start Test" above. You'll see a colored circle (Landolt C ring) with a gap on one side.
2. Find the Gap
Look at the ring carefully and click directly on the gap opening. If you cannot distinguish the ring from the background, click "I can't see the gap".
3. Get Your Results
After 14 rounds, you'll receive a detailed result indicating the severity of any red-green color vision deficiency detected.
How This Test Works
This test uses Landolt C rings — circles with a gap in one of eight directions. The ring is drawn in a color that people with red-green deficiency find difficult to distinguish from the surrounding background color. If you can see the ring clearly, you can locate and click on the gap; if you cannot distinguish it, the ring blends into the background.
The colors used for the ring and background are chosen along "confusion lines" in the CIE color space — pairs of colors that appear identical to people with a specific type of deficiency but are clearly different to those with normal vision. By varying these color pairs across 14 rounds, the test measures how well you can separate red-green hues.
The Landolt C Method
The Landolt C is a standard optotype used worldwide for visual acuity and color vision testing. Its simple shape — a ring with a single gap — provides a direction-based response that is language-independent and unambiguous. You simply click where you see the opening, making it accessible to users of any age or language background.
Why Gap Direction Matters
Unlike number-based tests where guessing is easy, the gap can appear in any of eight directions (up, down, left, right, and four diagonals). This makes random guessing unreliable (only 12.5% chance of a correct guess) and provides a more precise measurement of your ability to distinguish the ring from the background.
Scoring and Severity
Your score is based on how many of the 14 rounds you correctly identify the gap direction. Normal color vision typically achieves 90% or above. Scores between 70–89% suggest mild deficiency, 50–69% moderate deficiency, and below 50% indicates a strong red-green color vision deficiency.
Frequently Asked Questions
What is the difference between Protanopia and Deuteranopia?
Protanopia is caused by the absence of red-sensitive (L) cone cells, making reds appear very dark and easily confused with black or brown. Deuteranopia is caused by the absence of green-sensitive (M) cones, where greens blend into reds and yellows. Deuteranomaly (reduced green sensitivity) is the most common form, affecting about 5% of males.
Can women be red-green color blind?
Yes, but it is much rarer. Since the genes for red and green cone pigments are located on the X chromosome, women need both X chromosomes to carry the affected gene. This occurs in about 0.5% of women, compared to 8% of men who only need one affected X chromosome.
Is red-green color blindness curable?
There is currently no approved cure for inherited red-green color blindness. However, special tinted lenses and glasses can enhance color contrast for some individuals. Gene therapy research is ongoing and shows promise for future treatments.
How accurate is this online test?
This test provides a reliable screening indication, but results can be influenced by your display's color accuracy, brightness settings, and ambient lighting. For a definitive clinical diagnosis, visit an optometrist or ophthalmologist who can administer standardized tests under controlled conditions.
What colors do red-green color blind people confuse?
Beyond just red and green, affected individuals may confuse orange with green, brown with red, pink with gray, and purple with blue. The specific colors confused depend on whether the person has protan or deutan deficiency and how severe it is.
Can this test tell me how severe my color blindness is?
Yes. Based on how many of the 14 rounds you correctly identify the gap direction, the test indicates whether your deficiency is mild (70–89% correct), moderate (50–69%), or strong (below 50%). Mild cases may only struggle with subtle color differences, while severe cases cannot distinguish the ring from the background at all.
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