Amsler grid eye test is a visual testing tool that can identify the changes in the central vision. The test is used to monitor conditions affecting the macula. Macula is the central part of the eye which helps you see small fine details.
The Amsler grid test can help detect conditions like age-related macular degeneration (AMD), Diabetic macular oedema, blind spots, Macular pucker and more. Since macular problems may cause distortion or loss of central vision, early detection through an Amsler grid test can help early detection or progression.
What is an Amsler grid eye test?
An Amsler grid is a square grid consisting of horizontal and vertical lines with a dot right at its center. A patient is asked to focus on the central dot with one eye (the other is covered) and at the same time look at the surrounding lines. If the person sees the grid as distorted, blurry or if lines appear to be wavy or there are some parts missing in the grid, it may signal that the macula or some other parts of the retina are damaged. This grid test is a quick way to monitor your vision regularly. You can do it at home or in a clinic as a part of your regular eye check-up.
Types of Amsler grids
Marc Amsler, the Swiss ophthalmologist, who is known for the invention of the Amsler grid eye test, came up with not one, but seven different types (versions or charts) of this grid test. Most of the time, people mean chart 1 when they talk about this test. Following are the seven types:
Chart 1: This is the primary and the most common version with black lines on a white background. The grid is made up of 20 cells on each side, so each cell is 0.5 centimeters wide. At the center of the grid, there is a small dot located to focus on.
Chart 2: It is almost the same as chart 1. However, this chart has diagonal lines running from each corner to the center dot. It is useful for people who have a blind spot in their central vision and are still using the grid test to monitor their vision changes.
Chart 3: The structure of this version too is the same as in chart 1. However, this one has red lines on a black background. This version helps recognise the subtle color-related vision distortions in people.
Chart 4: This version is slightly different from all the ones above. This 10 cmX10 cm grid chart has no lines. It has a black background, a large white dot at the center and multiple random dots scattered in other spaces. This grid chart is used to differentiate between scotoma (blind spots) and metamorphopsia.
Chart 5: This grid chart only consists of 21 white horizontal lines on a black background with a white dot at the center. These horizontal lines allow to spot distortions caused by irregular curves in the cornea. This grid chart is especially helpful for people who struggle with reading.
Chart 6: It is almost the same as chart 5. This grid chart has black lines on a white background with a dot at the center. In the chart, the middle line and the two lines above and below it are closer together. This closer spacing helps identify small changes more easily.
Chart 7: This grid chart is made with white grid lines on a black background similar to the chart 1. However, the central area has smaller squares than the rest of the grid. These smaller squares makes it possible to spot even tiny distortions in vision.
You May Also Like: Aniridia: Symptoms, Diagnosis & Treatment
How does the Amsler grid work?
Amsler grid eye test works on a simple concept. If all the lines are appearing straight and evenly spaced, your macula is healthy. However, if your eyes detect any distortions such as curves, bends or gaps, this suggests there are irregularities in the macula.
Steps to use the Amsler grid
It is recommended to take the Amsler grid eye test at an optician’s clinic for accurate results. However, if your optician has advised you to take the test at home, follow the steps mentioned below:
- First, find a space with good lightning.
- If you wear contact lenses, prescription glasses or just reading glasses do wear them before taking the test.
- Hold the grid chart at a normal reading distance which is about 12 to 15 inches.
- Test each eye separately. Cover one eye and focus on the central dot with the other eye. Keep your gaze fixed on the dot while looking at the grid lines. Then, repeat with the other eye.
- Confirm whether the following pointers are true:
- You can see all four corners of the grid chart.
- All the grid lines are visible and appear straight.
- Make sure there are no dark spots or gaps..
- The lines are clear and not blurred or faded.
If any of these are not true, it’s advised to visit your optician as soon as possible.
You May Also Like: Behcet’s Disease: Causes, Symptoms & Treatment
Pro Tip: Hold the grid at the same distance each time you test.
When is the Amsler grid test the most useful?
The Amsler eye grid test is useful for monitoring distortions in the central vision and detecting conditions early that could damage the macula. They can help detect conditions such as:
- Age-related macular degeneration
- Diabetic retinopathy
- Scotomas (blind spots)
- Macular edema (swelling in the macula)
- Macular hole (a small break in the macula)
- Central serous retinopathy (fluid buildup under the retina)
- Macular pucker (wrinkling of the macula)
- Other macular or retinal disorders that affect central vision
Alternatives of Amsler grid eye tests
Following are a few alternatives of this Amsler eye test:
- Metamorphopsia chart: Popular as ‘M Chart’, this eye test can help identify both horizontal and vertical line distortions. However, this eye test can not determine the shape and size of the distortion as the Amsler grid eye test.
- Preferential hyperacuity perimeter (PHP): This eye test can help detect age-related macular degeneration.
- Shape discrimination hyperacuity (SDH): This is an online test that can help detect visual distortions through apps. It’s convenient for users to take the tests. They can perform the tests on their mobile phones or tablets anywhere and anytime.
You May Also Like: Vision Test for Contact Lenses
You May Also Like: Arcus Senilis (Corneal Arcus): Causes & Treatment
Frequently asked questions
What is the Amsler Grid test used for?
Amsler Grid test can be used to check central vision and detect damage in the macula, caused from macular degeneration or other retinal problems.
How do I use an Amsler Grid at home?
Hold the grid at reading distance, test one eye at a time, focus on the centre dot, and look for any wavy, missing, or distorted lines.
Can the Amsler Grid detect all types of vision problems?
No, it mainly detects central vision changes and macular issues, but it cannot identify all eye conditions.
How often should I use the Amsler Grid if I have macular degeneration?
Use it at least once a week, or as advised by your optician or eye specialist.
What should I do if lines on the Amsler Grid appear wavy or missing?
Contact your optician immediately, as this may indicate a change in your vision that needs prompt attention.
Dr Alastair Lockwood is an experienced ophthalmologist and eye health advisor. The major focus of his career is on preventing sight loss caused by glaucoma and other serious eye conditions. Along with undergraduate training at Cambridge University and clinical training at Oxford University, Alastair has also completed an MRC-funded PhD at the UCL Institute of Ophthalmology and Moorfields Eye Hospital. Dr. Alastair combines surgical expertise with a passion for research, regularly advising his patients on various eye care concerns and prescribing dry eye treatments and eye care products.
