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EOM: Eye Muscle Test and How It is Conducted
Published on June 5th, 2024
Australia
The eye muscle test (EOM) is a type of test carried out during a routine eye exam to evaluate how your eyes are moving and their function. During an eye movement test, the optometrist may look out for signs such as shaking eyes (nystagmus), inaccurate eye movements, crossed eyes and double vision. The optometrist will conduct an EOM test by getting you to sit up straight while staring at an object in front of you as they move the object in different directions. An eye muscle test is a simple and painless process and is an essential component of the regular eye test process.
What is an Extraocular Muscle Test?
An extraocular muscle test is an eye test carried out to examine any weaknesses or abnormalities in your eye muscles. An eye muscle test is part of the standard process when getting your eyes checked and typically involves the optometrist moving an object side-to-side, up and down and having your eyes follow the object. This will allow the optometrist to identify any signs of eye conditions that affect eye movement and position such as crossed eyes (strabismus), nystagmus (rapid and involuntary eye movement) and lazy eye (amblyopia).
What is the Purpose of an Extraocular Muscle Test?
The purpose of an extraocular muscle test is to determine whether your eyes are moving normally and ensure that both eyes are moving together. The optometrist will be able to see if you are exhibiting any signs of eye conditions that can impair normal eye movement. Therefore, it is important to maintain regular eye tests so you can have an eye movement test done.
How is an Extraocular Muscle Test Conducted?
An extraocular muscle test is conducted with an optometrist holding an object such as a penlight around 40 cm away from your face. They will then ask you to follow the object with your eyes while they move the pen up, down and side-to-side. The optometrist will carry out an extraocular muscle test along with other tests that also make up a comprehensive eye examination. These other tests can include a visual field test, a visual acuity test, a slit-lamp exam, a pressure test, a colour vision test, retinoscopy and a corneal topography test.
When is an Extraocular Muscle Test Recommended?
An extraocular muscle test is not necessarily recommended as it is one of the several tests included in an overall standard eye test. If you are noticing any changes to your vision, you would then be recommended to have an eye test, which will then involve an eye muscle test. Therefore, EOM testing would not be recommended on its own as the optometrist will need to check all other parts of your eye.
How are the Results of an Extraocular Muscle Test Interpreted?
The results of an extraocular muscle test are interpreted by the optometrist when visually assessing your eye movement. The optometrist will check whether your eyes are moving together or not and if they are moving smoothly without any jerking. These results may not appear in your prescription but that will depend on the type of eye movement-related eye condition you might have and its severity.
What are the Common Disorders Diagnosed with Extraocular Muscle Tests?
The common disorders diagnosed with extraocular muscle tests are crossed eyes (strabismus), nystagmus (rapid and involuntary eye movement) and lazy eye (amblyopia). The common disorders diagnosed with extraocular muscle tests are listed below.
- Crossed Eyes (Strabismus): Crossed eyes (strabismus) is an eye condition that commonly affects children and develops when one eye turns in a different direction than the other eye. Patients with strabismus have lesser control of eye movement hindering normal ocular alignment.
- Nystagmus: Nystagmus is characterised as an eye condition that affects eye movement. Nystagmus causes the eyes to involuntarily and rapidly move in up and down (vertical nystagmus), circular, or side-to-side (horizontal nystagmus) motions. Nystagmus can occur possibly due to malfunctioning regions of the brain that control eye movement or from issues related to the ear’s balance.
- Lazy Eye (Amblyopia): Lazy eye (amblyopia) is an eye condition where one of the eyes has worse vision than the other, due to developmental issues. Lazy eyes can occur when one eye does not develop the same level of vision skills as the other, causing the brain to favour the unaffected eye.
What Should Patients Know About Preparing for an Extraocular Muscle Test?
Patients should know that there is no special preparation necessary for extraocular muscle testing. However, it can be helpful for patients to try to avoid overexerting their eyes before their eye test to ensure their eyes are not fatigued.
How Does an Extraocular Muscle Test Compare to Other Eye Diagnostic Tools?
An extraocular muscle test is different compared to other diagnostic eye tests as it only involves looking at how your eyes move and does not typically require any special equipment. Other eye diagnostic tests usually employ certain tools to look further into the eye and to assess the quality of your vision.
Do Optometrists Conduct Extraocular Muscle Tests?
Yes, optometrists do conduct extraocular muscle tests. An optometrist will perform an extraocular muscle test as part of your routine eye test. The process will require you to follow an object with your eyes as the optometrist moves it in different directions while examining how smoothly your eyes move.
Can Children Undergo Extraocular Muscle Tests?
Yes, children can undergo extraocular muscle tests. Children do have extraocular muscle tests performed as they are one of the components of normal eye test procedures. Children need to have regular eye tests as their vision is still developing and are typically more vulnerable to developing eye diseases according to the American Academy of Ophthalmology.
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