Online eye and colour tests
How the common at-home eye checks work — colour vision, contrast, near vision, astigmatism and the Amsler grid — and where a screen check stops and an optometrist begins.
These are self-screening tools for general awareness, not a medical diagnosis. Screen brightness, colour calibration and room lighting all change what you see. See an optometrist or ophthalmologist for any real concern, for a proper eye test, and urgently if vision changes suddenly.
What at-home eye checks are good for
At-home eye checks are useful for one thing: nudging you to book a real eye test when something seems off. They can hint that your colour vision differs, that small print is getting harder, or that lines look distorted. What they cannot do is measure a glasses prescription, examine the health of the retina and optic nerve, or tell an everyday focusing error from a condition that needs treatment. Only a trained optometrist or ophthalmologist, with calibrated equipment, does that.
Each guide below explains one check: what it looks at, how the clinic version works, and where the at-home version stops.
The checks
Colour vision (colour blindness)
How the dotted-plate colour test works, and what red–green colour vision deficiency actually is.
Contrast sensitivity
Not the same as sharpness — how well you tell subtle shades apart, which matters for night driving and fog.
Near vision and reading
Why small print gets harder from your forties, and what a reading check does.
Astigmatism
When the eye is shaped more like a rugby ball than a football, blurring near and far.
The Amsler grid
A simple grid used to watch the central retina — wavy or missing lines are a reason to act.
Source: General optometry references; colour-vision screening is based on the pseudo-isochromatic plate method. This site does not diagnose. · checked 2026-09-04
Frequently asked questions
Can an online eye test replace a real one?
No. At-home checks can flag that something is worth looking into, but they cannot measure a prescription, examine the health of your eye, or diagnose a condition. A full eye test does all three and can catch problems with no symptoms yet.
How often should I have my eyes tested?
For most adults every two years is a common guideline, sooner if you notice a change, have diabetes, a family history of eye disease, or are over 60. Follow your optometrist's advice.
Why do results depend on my screen?
Colour, contrast and text size all depend on your display's brightness and calibration and on room lighting. That is why online checks are only a rough screen and a clinic uses standardised charts and lighting.
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