How Doctors Test Your Eye Muscles

A Doctor performing an Eye Examination
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Testing your eye muscle movements is a preliminary part of a comprehensive eye examination. This test is often referred to as extraocular movements testing or ocular motility testing.

How Is the Test Performed?

Your eye doctor or technician will ask you to sit up straight while you fixate your eyes on an object in front of you. The object of fixation is usually a pen, fixation light, or a small picture held between 12 and 16 inches in front of you. The object will be moved up and down and side to side using an "H-shaped" pattern. You will be asked to follow the object with your eyes while keeping your head completely still.

What Your Doctor's Looking For

Your doctor is looking for restrictions or abnormal movements of your eyes that may signify one or more of the following problems:

  • Nystagmus: An involuntary rhythmic shaking or wobbling of the eyes. Nystagmus can be horizontal or vertical or move in a diagonal direction. In most cases, Nystagmus is present from birth and can be a part of other developmental syndromes. Nystagmus can be present constantly or exacerbated by certain eye movements. If nystagmus is severe enough, visual acuity will suffer as the eyes are constantly moving back and forth. Often times, people with nystagmus hold their head or eyes in a certain direction that reduces the amount of nystagmus. This is called a null point.
  • Strabismus: One or both eyes is turned in, out, up or down. Strabismus is a condition that is often referred to as one having crossed eyes or being "wall-eyed" where one eye may go outward. Strabismus can be congenital (born with) or acquired (developed later in life.) Strabismus can cause problems with normal depth perception and put one at risk for developing a "lazy eye" or amblyopia. Amblyopia occurs when at a very young age, the eye is not being stimulated or used properly. Permanently decreased vision can occur.
  • Overshoot or undershoot of certain eye muscles: These signs could point to inherited conditions or syndromes, such as Duane's retraction syndrome.
  • Mechanical restrictions: Mechanical restrictions are commonly found in traumatic injuries, such as a blow to the eye. The bones that make up the floor of the orbit are fairly 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 doctor determine the cause of double vision, or diplopia. Double vision is always taken seriously as it can be a sign of neurological problems and in some cases can be a sign of a very serious health problem. Medical attention should be sought in cases of sudden onset double vision.
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Article Sources

  • Eskridge, J. Boyd, John Amos and Jimmy D. Bartlett. Clinical Procedures in Optometry. J. B. Lippincott Company, 1991.