Amsler Grid Eye Test: How to Use It and How It Works

The Amsler grid is a vision-testing tool with a square pattern (crossed vertical and horizontal lines that form squares). A dot in the middle of the grid serves as a focus point for those who take the test.  

Anyone who suspects a change in vision can self-administer the test at home in coordination with their eye doctor. Vision-care specialists can give these tests during checkup appointments.  

What Is It Used For?

The Amsler grid test detects visual field problems linked to defects at the back of the eye. If your vision has dark or missing areas, the Amsler grid reveal it.

Generally, the tool measures your eyes’ ability to recognize things, including shapes. Your doctor may recommend it for continuous vision monitoring if you have age-related macular degeneration (AMD).

Over time, AMD damages the macula, which helps your eye recognize the images you look at. In its early stage, the condition is called dry AMD.

Eye exams using special equipment may detect a few tiny bits of protein under the retina as the condition progresses. These are symptoms of deteriorating vision due to AMD damage.

Their detection signals immediate commencement of treatment.

The disease can eventually steal your eyesight if allowed to advance to the “wet” stage and beyond. By taking the Amsler grid test daily or as directed by your doctor, you can detect some early symptoms before too much retinal damage has occurred.

There are printable versions of the vision-saving test for patients with AMD or other problems affecting the retina.

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How to Use the Amsler Grid (Step by Step if Applicable)

The Amsler grid test is easy to self-administer. With the right setup and good lighting in your room, you’re good to go. To improve accuracy of the test, wear your vision correction glasses or contacts, if any.

The steps:

1. Hold (or tape) the grid about 13 inches away from your eyes. Ensure there is no glare affecting your vision.

2. Cover one eye and stare at the dark dot in the middle of the grid.

3. Without moving your open eye, describe your observation as follows:

• Are all the lines straight?
• Do you see wavy lines?
• Do some parts of the grid look blurry?
• Are there any dark areas?
• Are some squares missing?
• Are all the grid corners visible?

4. Document any abnormalities that you spot.

5. Repeat these steps with the other eye.

The purpose of the test is to track progression of your AMD. That is why it is important to note any unusual observation every time you have the test.

What Do My Results Mean?

You take the Amsler grid test with one eye covered to effectively assess central vision. If this aspect if your eyesight is normal, you should see the entire grid with your open eye fixated at the center dot.

All the corners should appear in your peripheral vision and there should be no broken lines or missing squares. If that’s not the case, there’s been a vision change in the affected eye that requires further evaluation as soon as possible.

See your doctor right away as these vision abnormalities are associated with late-stage AMD.    

The Importance of Macular Degeneration Detection

AMD is the leading cause of blindness in older people. Detecting the eye disease paves the way for treatment to prevent complete vision loss.

The main obstacle to early detection is the gradual progression of AMD without early warnings for retinal damage. The disease gets worse over time through three main stages.

These are:

• Early dry AMD: The patient experiences no outward symptoms in this stage.
• Intermediate AMD: Mild symptoms like poor vision in low lighting or blurred central vision may occur. For some patients, there are still no outward signs of eye damage at this point.
• Late AMD: Late-stage dry AMD and wet AMD are advanced stages of vision degradation. This is when straight lines may look crooked and dark spots appear within your central/peripheral vision.  

Ongoing monitoring and regular checkups give you the best fighting chance to protect your vision. By using the Amsler grid to test your eyesight every day, you can promptly spot problems that are not obvious.

Any such findings would warrant immediate eye examination for treatable late-stage dry AMD or wet AMD.

Self-Assessment vs. Doctor Assessment

Self-administered eye tests are highly appropriate and beneficial in a modern world where patients are playing a more active role in their own care. However, these home tests should not be considered alternatives to professional checkup and monitoring.

You still should share your Amsler grid test results with your doctor as directed. Only a qualified eye care specialist can accurately interpret your observations and provide proper advice.

Besides, the Amsler grid is not always sensitive enough to detect all AMD changes that occur over time. It’s useful, but not as a replacement for medical evaluation.

Comprehensive AMD diagnosis involves several other eye exams that patients can’t self-administer at home. These include a dilated eye exam and an optical coherence tomography (OCT).

Dilated Eye Exam

With a comprehensive dilated eye exam, your doctor examines the tissues at the back of your eye for AMD-related defects. Your pupil will be dilated (widened) using special drops for a clearer view during the assessment.

Optical Coherence Tomography (OCT)

Optical coherence tomography is an imaging technique for investigating diseases that affect the retina. Your doctor can use it to take pictures of the macula and assess it for any aging-related damage.  

Who to See for Diagnosis?

Since AMD affects your eye health, you should see a vision care specialist for diagnosis and treatment. Your ophthalmologist would be the most appropriate professional to help monitor and manage your condition.

Not only are ophthalmologists eye care specialists, but they are also medical doctors. They’re best suited to diagnosing and treating all eye diseases, including surgically.

That said, you can see an optometrist for AMD tests, but not for treatment. While optometrists aren’t medical doctors, they can perform eye exams, write prescriptions, and treat certain eye disorders.

An optometrist can monitor your condition for some time, running any necessary tests to track your disease’s progression. They’ll refer you to an ophthalmologist immediately these tests show signs of retinal damage.    

When to See a Doctor

The duration between the first AMD symptoms you experience and the commencement of treatment is very critical to vision loss prevention. See your ophthalmologist immediately you notice vision changes or abnormalities such as:

• Blurred central vision
• Difficulty seeing in low light
• Blank spots in your central vision
• Previously bright colors appear faded and less distinguishable
• Straight lines appear wavy (for example fence posts or door frames)
• Difficulty threading a needle
• Difficulty reading a clock
• Difficulty recognizing familiar faces
• Overall inability to see details clearly

All these symptoms are red alerts for potentially advanced AMD.  If you experience any of them with or without or a grid test, you require immediate medical help.

References

1. Amsler Grid. StatPearls Publishing.

2. Have AMD? Save Your Sight with an Amsler Grid. (May 2020). American Academy of Ophthalmology.

3. What is AMD? (June 2021). National Eye Institute.

4. Difference between an Ophthalmologist, Optometrist and Optician. (February 2019). American Association for Pediatric Ophthalmology & Strabismus.

5. Age-related macular degeneration (AMD). (April 2021). National Health Service.