HOW
VISION
WORKS
Plain-English guides to how your eyes work, what the tests measure, and how to read your results. Each one links to a free test you can try right now.
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Are Online Vision Tests Worth It?
An honest, verified comparison of the big online vision tests — ZEISS, ACUVUE, Warby Parker, and us — what each really does, and the catch.
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Color Blind Test for Kids
How to test a young child who can't read numbers (use shapes), the signs to watch for, and why it matters at school.
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How Accurate Are Online Color Blindness Tests?
The calibration problem — why your uncalibrated screen is the real limit, what makes a test trustworthy, and why you can pass one site and fail another.
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How Accurate Are the Windows Color Filters?
Nobody outside Microsoft can say — the transform is not published, and three independent capture paths cannot observe it. Also why your screenshots do not show what you see.
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Which Color Vision Test Is Most Accurate?
Ishihara vs the D-15 vs the anomaloscope vs online tests — what each one is for, and which is the clinical gold standard.
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What Is an Anomaloscope?
The gold-standard test explained — the Rayleigh red-green match, what it reveals that plates can't, and why a screen can only approximate it.
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Am I Colorblind?
The everyday signs of color blindness — and how to check for yourself in two minutes.
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How to Test for Astigmatism at Home
The radial-line fan test, why some directions look darker, and what a home check can and can't tell you.
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Why Is My Night Vision Getting Worse?
Why night and fog get harder even with 20/20 vision — the contrast-sensitivity connection.
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How Far Should You Sit From Your Screen?
The right monitor distance, the 20-20-20 rule, and why distance matters for any eye test.
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Is Blue Light Bad for Your Eyes?
The honest answer: no — screen blue light doesn't damage your eyes and blue-light glasses aren't proven to help. Here's what really causes eye strain.
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Color vision
Color Blindness, Explained
The types (protan, deutan, tritan), what causes it, who has it, and how it actually looks day to day.
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How Ishihara Plates Work
Why a hidden number appears — or vanishes — in a field of colored dots, and what online plate tests can tell you.
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Can Color Blindness Be Cured?
Why inherited color blindness is permanent, and what color-boosting glasses actually do.
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Sharpness & the eye
What 20/20 Vision Actually Means
Snellen fractions decoded, why 20/20 isn't the maximum, and whether you can really test acuity on a screen.
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Contrast Sensitivity vs. Sharpness
Why you can have "perfect" 20/20 and still struggle in fog, glare, and dim light — and what the difference reveals.
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What Does a Dominant Eye Mean?
Eye dominance explained — what it is, why it matters for aiming, and how to find yours.
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What Is the Eye's Blind Spot?
Why every eye has a receptor-free gap, where it sits, and why your brain hides it from you.
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Reference
Vision & Eye Test Glossary
Every term used across OpticQuiz — acuity, contrast, JND, Ishihara, hyperacuity — in plain English, each linked to its test.
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