The Amsler grid is a simple tool for monitoring vision in conditions like age-related macular degeneration (AMD). It helps detect distortions and visual impairment, allowing for timely intervention.
You're sitting in the doctor's office, and you've just received the news that you've been diagnosed with age-related macular degeneration (AMD) — a vision-threatening condition.
As your doctor explains more about the condition, they hand you a sheet with grid lines and tell you it's called an Amsler grid. They also mention using it to monitor your vision, but you're left feeling overwhelmed and unsure about how it works.
In this article, let’s discuss what an Amsler grid is and what you should know about it.
Importance of regular monitoring in AMD
Wet AMD is an advanced form of AMD. It is a prevalent cause of significant vision loss, particularly among older adults. While it accounts for only 10 percent of AMD cases, it is responsible for 90 percent of cases resulting in legal blindness. It is estimated that in 2022, there were approximately 203 million people worldwide affected by AMD. Around 15% of individuals with early AMD may progress to the late stage within 10 years. Furthermore, if an individual already has late AMD in one eye, their risk of developing it in the other eye ranges from 35 to 50%.
Regular self-monitoring plays a crucial role in detecting changes associated with wet AMD. Healthcare professionals often recommend the use of an Amsler grid, which is a simple tool that individuals can utilize at home to assess their vision. The Amsler grid aids in identifying distortions in central vision or the presence of visual impairment. By regularly assessing one’s vision with the Amsler grid, an individual can detect any changes indicative of progression to wet AMD.
Identifying wet AMD as early as possible allows for timely intervention and treatment. Initiating treatment late may lead to irreversible vision loss.
What is an Amsler grid?
The Amsler grid is a tool used to detect and monitor various disorders of the macula and optic nerve head, specifically those affecting the central visual field. This square-shaped grid serves as an inexpensive tool for home monitoring, enabling early detection of scotoma (impaired vision) and metamorphopsia (visual distortion) caused by wet age-related macular degeneration.
The Amsler grid owes its name to a renowned Swiss ophthalmologist named Marc Amsler, who introduced this chart in 1947. Initially, the basic grid featured white lines on a black background, also sometimes referred to as the original Amsler grid. However, in recent years, a modified Amsler grid has become more prevalent.
Interestingly, in a research study presented at The Association for Research in Vision and Ophthalmology (ARVO) in 2002, it was found that for patients with visual acuity better than 20/50 the modified Amsler grid was preferred and could detect visual field abnormalities better. On the other hand, for patients with a lower level of visual acuity of 20/50 to 20/200, the original Amsler grid was preferred and was better. The author concluded with the advice of tailoring the choice of grid based on the patient's visual acuity level.
How does the Amsler grid work?
The Amsler grid can help detect visual field abnormalities, such as scotoma (impaired vision) and metamorphopsia (visual distortion). Metamorphopsia, characterized by visual distortions, is identified on the Amsler grid when the small squares appear wider or narrower than adjacent ones.
In the case of macropsia (objects or things appear larger than they actually are), the parallel lines seem to widen away from each other. In contrast, micropsia (objects or things that appear smaller than they are) causes the lines to draw closer – a sign of macular edema. These distortions provide crucial information about the condition of the macula and the optic nerve head.
Scotoma, on the other hand, refers to an area in the visual field where vision is absent or deficient. The Amsler grid can reveal scotomas. These scotomas may be absolute (completely lacking visual recognition despite increasing stimulus intensity) or relative (the stimulus becomes visible if the intensity is increased).
When observing the Amsler grid, a relative scotoma appears as a partially obscuring veil over the smaller squares, often with varying shapes. Dimming the illumination of the grid can enhance the appreciation of such scotomas.
As mentioned, one of the advantages of the Amsler grid is its simplicity and accessibility. Patients can easily perform the test in the comfort of their own homes, making it a practical and cost-effective method for monitoring their visual health.
Step-by-step instructions for using the Amsler grid
If you have AMD, the American Academy of Ophthalmology recommends daily self-testing using the Amsler grid. This is crucial because individuals may not always notice the gradual changes in their vision loss.
Using the Amsler grid is a straightforward process you can easily do at home. Just follow below step-by-step instructions:
Find a well-lit area and position the grid approximately 33 cm (13 inches) from your eye. It's important to avoid direct exposure to bright lights right before using the grid to prevent any temporary visual stress.
If you wear glasses for near vision, keep them on while using the grid.
Close one eye and focus your open eye on the central dot of the grid. Make sure that the eye is centered on the grid so that all four corners are simultaneously visible.
While keeping your eye fixated on the central dot, carefully observe the lines on the grid. Pay attention to whether the lines appear parallel or distorted (indicating metamorphopsia). Additionally, note if any of the small squares are missing or blurry.
If you notice any areas of abnormality, mark the grid accordingly. This will allow you to compare your observations later for any changes.
Recording and sharing results with your eye doctor
Using the Amsler grid goes beyond personal observation—it serves as a valuable tool for communicating with your eye doctor. Here's how you can effectively record and share your results:
While using the grid, focus on the central dot and mark down in the recording sheet what you see with specific details:
a. Can you see the entire grid, including all corners and sides?
b. Do any of the lines appear blurry or disappear?
c. Are there any holes or dark spots on the grid?
d. Are all the boxes appearing the same size?
If you notice any concerning changes in your vision, such as worsening of wavy or bent lines, differing box sizes or shapes, distorted or missing lines, or unusual discoloration, it's crucial to contact your eye doctor immediately.
To facilitate communication with your eye doctor, take the marked grid with you to your next appointment so you can discuss it with your eye doctor.
Remember, although the Amsler grid is a valuable self-monitoring tool, it shouldn’t substitute regular visits to your eye doctor. Furthermore, it is essential to recognize that the Amsler grid is not designed for medical diagnosis.
In conclusion, the Amsler grid is a valuable tool for monitoring vision and detecting changes associated with wet AMD. By using the grid regularly, you can identify distortions and visual impairment indicative of disease progression, allowing timely intervention. So, download and use the appropriate Amsler grid depending on your visual acuity, work with your eye doctor, and prioritize your eye health for a future of clear sight.
Printable - Amsler grid (free to download):
1. Original Amsler grid with a recording sheet - printable (for visual acuity 20/50 to 20/200)
2. Modified Amsler grid with a recording sheet - printable (for visual acuity better than 20/50 )
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