The eye consists of six extraocular muscles that control its movement. Specific muscles help to move the eye to the right, left, up, down and at an angle.
Also Known As
- The muscles lie within the orbit and are attached to the sclera (white part of the eye or wall of the eye).
- The levator palpebrae superioris is the only muscle that elevates the eyelid.
- The superior rectus muscle and the inferior oblique muscle move the eye upwards (upgaze).
- The inferior rectus and superior oblique turn the eye downwards (downgaze).
- The lateral rectus turns the eye outwards towards the ear (abduction). The medial rectus turns the eye inwards towards the nose (adduction).
- The superior rectus and superior oblique rotate the eye medially. The inferior rectus and inferior oblique rotate the eye laterally.
Muscles control eye movements. Recti and oblique muscles help with eye movement. The levator palpebrae superioris controls the superior eyelid movement. The muscles allow people to look in different directions without having to turn their heads.
Associated symptoms & disorders
Some of the diseases associated with eye muscles include:
- Blepharospasm refers to a condition in which the eyelids experience unusual, involuntary spasms or blinking. It is associated with an abnormal function of the basal ganglion. The basal ganglion is the area of the brain that controls the muscles.
- Oculomotor nerve palsy occurs when the nerves that control the eye muscles are impaired. The disease can result in diplopia (double vision) and ptosis (drooping eyelids).
- Myokymia refers to the twitching of the orbicularis muscle which controls the eyelid. The twitching can come from excessive intake of coffee, fatigue and stress.
- Strabismus is a condition where the eyes are not aligned properly. It can lead to double or vision loss. It is caused by an imbalance of muscles that control eye movement.
- Myasthenia gravis refers to a disease which results in fatigue and weakness of any of the muscles. Communication breakdown between the muscles and the nerves causes it. The condition can lead to double vision and drooping eyelids.
- Duane syndrome is a congenital and non-progressive type of strabismus. It is as a result of the nerves to the eye muscles not being properly wired. The individual has problems rotating the eyes both inwards and outwards.
- With the rare Miller Fisher syndrome, the eye muscles become paralyzed. There is also abnormal muscle coordination and a missing tendon.
Diagnosis of associated disorders
The eye care professional does a comprehensive eye examination which may include:
- Doing a physical exam
- Taking down the medical history
- Tonometry to measure intraocular pressure
- Ophthalmoscopy to check the eye including the back
- A slit lamp examination to check the eye under high magnification
- Imaging tests such as computed tomography or magnetic resonance imaging
- The professional evaluates the muscles responsible for eye movement. He/she watches the eye movements as patients follow a moving object. The professional will look for any weaknesses, poor control or coordination in the muscles.
- Because there are different conditions involved, specific tests will be used to diagnose the various diseases. For example, in the case of ocular nerve palsy, the cause of the nerve impairment has to be determined based on medical history, clinical signs and a laboratory test.
Treatment of associated disorders
Some diseases like myokymia and blepharospasm require no treatment. They usually resolve on their own. However, the doctor may recommend certain medications such as painkillers and anti-inflammatory drugs to help with the symptoms.
Several treatment options such as Oculinum injection can reduce the severity of blepharospasm. Corticosteroid injections can straighten the gaze of oculomotor nerve palsy patients. They can also open the eyelids of these patients.
Use of eyeglasses and contact lenses can help to treat strabismus.
Other treatment options include surgery for diseases like blepharospasm. Myectomy is the surgical procedure that removes some of the muscles and nerves of the eyelids. For strabismus, the surgeon tightens or loosens the muscles. This way, he/she changes the alignment of the eyes.
Alternative forms of treatments such as acupuncture, biofeedback, chiropractic, nutritional therapy and hypnosis are being used. However, they are yet to be proven.