What is Amsler grid?
Amser Grid was developed by Marc Amsler, a Swiss ophthalmologist. Amsler grid is used for the Macular degeneration screening test. The Amsler grid evaluates the 20 degrees of the visual field centred on fixation. It is useful for detecting central vision defect which is due to defect in the Macula (Central part of the Retina). It screens and monitors macular diseases. This Test required normal room lighting used for reading.
How to use the Amsler grid?
To use the Amsler grid the normal room light is needed, The examination is performed at the undilated pupil. The chart is held at a distance of 28-30 cm. For the patient above 40 years near vision correcting glasses is required, Single eye test will be done, ask the patient to close another eye. A patient is asked to look at the central dot of the Amsler grid chart, in normal cases, the lines of the chart will be seen straight and parallel, if patient notice abnormalities such as distortion of lines, broken line, missing line, wavy lines, a patient will be asked to draw the location and sign as he/she sees in the chart.
What does the Amsler grid test for?
This test help for early screening and detection of the following eye diseases.
- CSCR (Central Serous Chorio Retinopathy)
- Macular Oedema
- Age-Related Macular Degenerations
- Clinically Significant Macular Edema
- Choroidal Neovascularization at Macular area
- Macular Holes
- Other Macular Eye Disease
Amsler Grid Chart
There are seven charts in the Amsler grid, each chart consist of a 10 cm outer square.
Chart Name and Functions
1. Standard: Amsler Chart
Chart 1 standard chart is the basic version, which is the most familiar and widely used chart among all the charts. In this chart, the grid consists of 0.5 cm squares (each for 1° visual field), which totally measures 10 cm X 10 cm size. Most commonly grid is in white colour with a black background. The image is below in the post.
2. Central: Scotoma Diagonal
The Central Scotoma Grid is used in cases where the central point is not seen.
3. Color Scotoma: Red on Black
The Color Scotoma Grid is specifically used for detecting color scotomata.
4. No lines: Dots
The Amsler Grid With No Lines reveals only the scotoma without any lines or squares for distortion.
5. Metamorphopsia: Parallel Lines on Black
The Metamorphopsia Grid of Parallel Lines provides a somewhat simplified version for patients having difficulty with the grid of squares. It should first be presented horizontally and then vertically.
6. Metamorphopsia: Reading Added Central Lines
The Metamorphopsia Reading Grid provides some additional lines in the central area used for reading.
7. Juxta-central: Standard with Small Squares
The Juxta Central Grid supports the closer examination of disturbances in the central rectangular area. Each of the smaller squares approximates 1/2 degree. The larger squares represent 1 degree.
How to do Online Amsler Grid Test
Close your one eye, If you are a glass wearer wear the glass and cover one eye then keep this screen at 14 to 16 inch away from your eyes, focus on the dot in the centre.
Answer these questions
- Do any of the lines look wavy, blurred or distorted?
- Are there any missing areas or dark areas in the grid?
Repeat the same procedure for another eye.
If both answers are NO then this test is normal.
If you have a YES answer to the above question, Please visit your eye care professional immediately.
Disclaimers: The grid does not replace having your macula tested by an eye care professional, particularly if you are over 50 yrs old or have any risk factors for macular degeneration.