Eye muscle testing is done to reveal restricted or abnormal eye movement. This may be due to eye muscle weakness or another issue with functioning and can indicate an optical condition such as strabismus (i.e., being cross-eyed). It may sound like something only done in special cases, but it’s actually a preliminary test and an essential part of anycomprehensive eye examination.
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Your ophthalmologist may also refer to eye muscle testing as extraocular movement testing or ocular motility testing. Here’s what you can expect at your appointment.
How Eye Muscle Testing Is Performed
The test itself is simple. Your eye healthcare provider or technician will ask you to sit up straight while you stare at an object in front of you, which is usually a pen, fixation light, or small picture held 12 and 16 inches away.
They will move the object up and down and side to side in an H-shaped pattern.
You are asked to follow the object with your eyes while keeping your head still.
What Is an Eye Exam?
What Your Healthcare Provider Is Looking For
In performing eye muscle testing, your healthcare provider will look for the following:
Shaking of the Eyes
Involuntary, rhythmic shaking or wobbling of the eyes characterizes a condition known asnystagmus.The shaking can be horizontal, vertical, or diagonal. In most cases, the condition is present from birth and can be a part of other developmental syndromes.
People with nystagmus can sometimes direct their head or eyes in a certain way that reduces symptoms. This is called a null point.
Misalignment
Your healthcare provider will look to see if one or both eyes is turned in, out, up, or down. This indicatesstrabismus, and people with the condition are often referred to as “cross-eyed” or “wall-eyed.”
Strabismus can be congenital (from birth) or developed later in life. It can also cause double vision (see below). The condition can cause problems with normal depth perception and put one at risk for developing amblyopia (“lazy eye”).
Amblyopiabegins at a very young age when the eye is not stimulated or used properly. Permanently decreased vision can occur.
“Overshooting” or “undershooting” of certain eye muscles simply means that your eye movement accuracy is off. These signs could point to inherited conditions such asDuane’s retraction syndrome, a form of strabismus that affects horizontal eye movement.
Mechanical Restrictions
These are commonly found intraumatic injuries, such as a blow to the eye. The bones that make up the floor of the eye orbit are thin. Blunt trauma to that area can blow out these bones, causing an eye muscle to get trapped or hooked in the bone.
Double Vision
Eye muscle testing can help your healthcare provider determine the cause ofdouble vision, ordiplopia, which can occur in one or both eyes. Medical professionals always take double vision seriously as it can be a sign of neurological problems.
Potential muscular causes of double vision include strabismus,myasthenia gravis(a neuromuscular condition causing muscle weakness), a side effect of hyperthyroidism (Graves' disease), and damage to the nerves surrounding eye muscles.
If you experience sudden-onset double vision, see a healthcare provider immediately.
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Ophthalmology.What is Nystagmus?
American Academy of Ophthalmology.Amblyopia. what is lazy eye?
AAPOS.Duane syndrome.
Stanford Health Care.Causes of double vision.
National Institutes of Health. Medline Plus.Extraocular Muscle Function Testing.
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