How to use the Amsler grid test
- Calibrate your screen with a bank or ID card so that each square is 5 mm wide. The calibration is shared with the online eye test and the astigmatism test.
- Choose the grid style (black lines on white, white on black or red on black) and keep using the same one. Set the viewing distance, normally 30 to 35 cm (12 to 14 inches).
- Put on your reading glasses if you use them, cover one eye and press Start the test.
- Look only at the centre dot. Without moving your eye, notice whether all lines are straight, all squares are the same size and all four corners are visible.
- Answer the four questions and, if something looks wrong, press Mark affected areas and draw over the wavy, blurred or missing parts. Undo and Clear marks correct mistakes.
- Save and continue to the other eye. Each result is saved with the date, and the Compare your results over time section shows earlier grids side by side. Use PNG to download a result for your eye doctor.
What is an Amsler grid?
The Amsler grid is a simple square grid of straight lines with a dot in the middle, named after the Swiss ophthalmologist Marc Amsler, who introduced it in the 1940s. The standard version is 10 cm square and divided into 20 × 20 squares of 5 mm. Held at about 30 cm, each square covers roughly one degree, so the whole grid tests about the central 20 degrees of your field of vision. That central area is served by the macula, the small part of the retina responsible for sharp detail, reading and recognising faces.
When the macula is healthy, the lines look straight and evenly spaced. When fluid, swelling or scarring lifts or distorts the retina, the light-sensitive cells are pushed out of their normal positions and straight lines can appear wavy or bent (metamorphopsia). Areas where cells are not working can appear blurred, grey, faded or missing (a scotoma). Because the brain fills in gaps from the other eye, these changes are easy to miss with both eyes open, which is why each eye is tested separately.
What the questions mean
| Question | Why it is asked |
|---|---|
| Can you see the centre dot? | A missing or faded dot can point to a problem right at the centre of the macula. |
| Can you see all four corners? | Missing corners or sides can indicate a gap in the central field of vision. |
| Are any lines wavy or bent? | Distortion is a typical early sign that the macula has changed shape. |
| Are any areas blurred, missing or dark? | Blurred or blank patches can mean that part of the macula is not working well. |
Who uses an Amsler grid and how often
Eye doctors often give an Amsler grid to people with age-related macular degeneration (AMD), especially the dry form, so that they can spot a change towards the wet form early, when treatment is most effective. It is also used to follow diabetic macular oedema, central serous chorioretinopathy, macular holes, epiretinal membranes and some medicines that can affect the retina. Many people at risk are advised to check each eye daily or a few times a week, but follow the schedule your eye doctor gives you. If you have no eye condition, an occasional check is fine, and it never replaces a regular eye examination.
The most important thing is change. Some people with a known condition always see a little distortion. What matters is a distortion or missing area that is new, larger or different from before, which is why this page saves your marked grids with the date.
When to get help
Contact an eye doctor promptly, ideally within a few days, if you notice any new wavy lines, distortion, or a blurred, dark or missing area on the grid. If the change appeared suddenly, or comes with a curtain or shadow across your vision, flashes of light with many new floaters, or eye pain, seek urgent medical care the same day. Do not wait for your next routine appointment and do not rely on a normal-looking grid if your vision feels different.
Screen, distance and printing
A screen can show the grid at the right physical size only after calibration, and many phones are too narrow for the full 10 cm grid. On a small screen the tool shows only the central squares at their true 5 mm size and tells you so; use a larger screen or a printed copy for the full grid. Print grid produces a clean A4 or Letter sheet with a 10 cm grid. Check it with a ruler: if the printer scaled it, print again at 100% or Actual size with Fit to page turned off. Colours, brightness, Night Shift and blue-light filters also change how the grid looks, so test in similar conditions each time.
The Amsler grid is a screening and self-monitoring aid. It can miss early changes and it cannot diagnose AMD or tell different conditions apart. A dilated eye examination, often with an OCT scan of the retina, is what diagnoses macular conditions. For other checks see the colour blind test and the other eye and hearing tests.
Privacy: the test runs entirely in your browser. Your answers, marks and history are stored only in this browser's local storage and are never uploaded. PNG exports are created on your device.
Frequently asked questions
What is an Amsler grid?
An Amsler grid is a square grid of straight lines with a central dot, usually 10 cm wide with 5 mm squares. Looking at the dot with one eye at a time shows whether the lines in your central vision look straight and complete, which helps people notice changes in the macula.
How often should I use the Amsler grid?
Follow your eye doctor's advice. People with macular degeneration or another macular condition are often asked to check each eye daily or several times a week. Without a known condition, an occasional check is enough, together with regular eye exams.
What does it mean if the lines look wavy?
Wavy or bent lines (metamorphopsia) can be a sign that the macula has changed shape, for example from fluid under the retina. New wavy lines should be checked by an eye doctor promptly, and sudden changes need urgent care the same day.
Can I print the Amsler grid?
Yes. Press Print grid to get a clean A4 or Letter page with a 10 cm grid. Measure it with a ruler; if it is not exactly 10 cm wide, set the print scale to 100% or Actual size. Keep the sheet somewhere you will see it, such as on the fridge, and date each check.
Is the Amsler grid a test for macular degeneration?
It is a screening and monitoring aid, not a diagnostic test. It can reveal distortion or missing areas that are typical of macular degeneration and other macular problems, but a normal grid does not rule them out and an abnormal one needs an eye examination to find the cause.
Should I wear my glasses for the Amsler grid test?
Yes, wear the glasses you use for reading at 30 to 35 cm. Without them the whole grid may look blurred, which is a focusing problem rather than a sign of macular disease.
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