Overview of the Amsler grid test
The Amsler grid is a tool that opticians use to detect vision problems resulting from damage to the macula (the central part of the retina) or the optic nerve.
Early diagnosis means early treatment, so it can help limit or reduce vision loss. If you are at risk for other eye diseases, you can use a macular degeneration test chart at home to monitor your vision.
How to use
Testing your eyes with Amsler Grid is very easy and only takes a few minutes. Here are the basic steps:
- Examine your eyes under normal lighting in the reading room.
- Wear the glasses you normally wear for reading.
- Hold the grid approximately 14 to 16 inches from your eyes.
- Examine each eye separately: Place your hand over one eye while examining the other eye.
- Look at the point in the centre of the grid and answer these questions:
- Do any of the lines in the grid appear wavy, blurred or distorted?
- Do all the boxes in the grid look square and the same size?
- Are there any “holes” (missing areas) or dark areas in the grid?
- Can you see all corners and sides of the grid (while keeping your eye on the central dot)?
- Switch to another eye and repeat.
Important: Report any irregularities to your optician immediately. Mark areas of the Amsler grid that you’re not seeing properly (print two grids if you notice problems in each eye), and bring the grid(s) with you when you visit your optician.
Check your eyes with the Amsler grid as often as your optician recommends or whenever you notice a significant change in your vision.
Amsler grid types
Seven different versions of the Amsler Grid are available to identify or explain metamorphosis and scotoma.
- Grid 1 is the most common basic version of Amsler grids.
- Grid 2 is the overlay that you can place on the basic Amsler grid with four diagonal lines. This will help you focus on the centre point if you have a central scotoma (a blind spot in the middle of your field of vision).
- Grid 3 has a black background with red stripes and red dots unless it is the same as Grid 1. This grid can help diagnose disorders with associated red distortion, such as a pituitary tumour, which can lead to partial blindness, toxic maculopathy, or neuropathy toxic optics.
- Grid 4 is used to distinguish between blind spots and distortions. This grid uses a black background with a large central white dot with small dots placed randomly on the grid. There are no lines on this grid.
- Grid 5 uses a black background with white horizontal lines with a white dot in the middle. Horizontal lines help identify distortions in curved sections of the cornea. This is especially helpful if you have difficulty reading.
- Grid 6, similar to Grid 5, has a white background and black stripes. On the side of the black dot in the middle, the horizontal lines are closer than grid 5. This will help you identify fine visual distortions in the centre of your visual field.
- Grid 7 is similar to Grid 1, with a smaller grid except around the centre. This allows the disease to be detected in half a degree and helps detect macular degeneration.
Black or white background for the Amsler grid test
If you search for Amsler grids online, you will generally see examples of grid 1 except for the white background and the black dashes, and the black centre point.
Amsler created this test with white stripes and a white centre point on a black background. A modified version of the Amsler grid on a white background. White background with black lines is more visible, although it is not clear if they are equal inefficiency.
How to perform the Amsler network test at home
Before beginning this self-exam process at home, it is best to discuss it with your ophthalmologist and perform the first test in the clinic or hospital to ensure proper training. Before starting this test, it is important to avoid bright lights. Follow the instructions below at least once a week to perform the Amsler Self-Manage Network Test.
To prepare for the Amsler network test at home:
- Wear corrective glasses or contact lenses that you normally wear.
- 10 cm at a distance of approximately 13 inches from the eye you are examining.
Identify these characteristics:
- Is there a white dot in the middle?
- Can you see all four corners and four sides of the grid while focusing on the point in the middle?
- Are there any gaps or blurry sections of the grid when focusing on the centre?
- Are there wavy lines (horizontal or vertical) on the grid when focusing on the centre?
- Are there moving lines, flickering sections, or vibrations on the grid when focusing on the centre?
Ideally, all lines should appear parallel. If the lines are distorted or disappear, you should mark the marked areas. You can do this by specifying the number of squares between the point and the anomaly while testing.
Distorted or warped lines indicate metamorphosis while disappearing lines indicate blind spots (scotomas). Since changes in the distortion area may indicate a progressive state, a stabilized state, or an improvement in your condition, place the marked ambler grid for reference later.
Disadvantages of the Amsler grid test
While the Amsler Grid is easy to use at home and monitors for improvements or changes in macular degeneration, there are some downsides to using the Amsler Grid.
Identifying blind spots is less accurate compared to other testing methods. Only 50 per cent of blind spots can be detected using the Amsler grid. When the size of the blind spot is less than 6 degrees, a large percentage of the blind spot is lost through the Amsler grid. Furthermore, only 30 per cent of those who use the Amsler grid, find extraordinary results with the tool.
Alternative eye tests for the Amsler network
If you do not want to use the Amsler Grid to track improvements or changes in blind spots or visual distortions, there are several alternatives available to use.
- The M chart (morph chart) helps to identify horizontal and vertical distortions. However, unlike the Amblers grid, the shape and magnitude of the distortion cannot be determined.
- The Preferential Hyperkinetic Circumference (PHP) test is available on home medical devices to help identify age-related macular degeneration. Small studies suggest that the PHP test may be more accurate in detecting age-related macular degeneration. However, PHP has a high false-positive test rate in healthy individuals, which means that when the test is positive, the person does not actually have the disorder.
- Shape Discrimination Hyperactivity (SDH) is an electronic method for calculating visual distortions. My VisionTrack is an iOS application that uses this method to easily track the signs of macular degeneration. With smart technology, users can test themselves at home twice a week on their phone or tablet. If the software detects any changes, the application will notify the prescribed ophthalmologist. A prescription is required to register with SDH related applications.