eye movement disorders

review of extraocular muscle and its :function and innervation

Superior rectus , inferior rectus , medial rectys , inferior oblique , levator paplebra superiorus >>>>> oculmotor nerve(III) Superior oblique >>>> trochlear (IV) Lateral rectus >>>> abducens (VI)

***Eye movements may be abnormal because there is:  * an abnormal position of the eyes.  * a reduced range of eye movements.  * an abnormality in the character of the eye movements.

Strabismus = squint : is deviation of an eye’s visual axis from it’s normal position. •Eso : inward •Exo: outward •Hyper: superiorly •Hypo: inferiorly ----------------------------- •Tropia : always deviated ( manifest squint) •Phoria : sometimes deviated (latent squint)

eye movement disorders : 1 non-paralytic squint (concomitant) 2. paralytic squint ( incomitant )

Non paralytic squint : 1- is when the sequint accurs in all direction of gaze. 2- movment of both eyes are full( no paresis ) if tested separately … but only one eye is directed towards the fixation target. 3- extraocular muscle and nerve are grossly normal . 4- the angle of deviation is constant and unrelated to direction of gaze .

5- the commonest sequint that seen in childhood. 6- etiology : * idopathic ( develop in normal child with normal eyes) Abnormality in the cental coordination of eye movements 7- diplopia is absent . 8- can be monocular , alternating , intermittent. 9- present of amblyopia

Amblyopia : Called lazy eye. Is a disorder of sight due to the eye and brain not working well togater it resuit in decreased vision . Cause can be any condition that interferes with fousing during early childhood. Accurs in unilateral strabismus . Is reversible before 7-8 years.

10 – history …-Note the presence of deviation of the eye -decreased vision ( amblyopia) -If present family history No diplopia - - no tilt head

11- examination and investigation ……… Determination of acuity-- - determination of any refractive error . - detection of any abnormality in eye movement (H shape). - cover uncover test. - careful examination of the eyes ( dilated funds view).

12- non - paralytic squint with no associated ocular disease is treated as follows: • Any significant refractive error is first corrected with glasses. • Surgical intervention to realign the eyes may be required for functional reasons (to restore or establish binocular single vision) or for cosmetic reasons (to improve appearance and prevent a child being singled out at school)

paralytic squint 1- there is under action of one or more of the eye muscle due to a nerve palsy or mechanical restriction of the muscles . 2- maximally demonstrated by looking in the direction of action of weakened muscle . 3- present with diplopia .

4- etiology : Neurogenic lesions ( congenital hypoplasia or absence of nucleus … third, fourth,sixth cranial nerve palsies) Neoplastic lesions Inflammatory lesions : encephalitis, meningitis…. Infectious lesions of cavernous sinus and orbit . Vascular lesions : HTN … DM…. Atherosclerosis …heamorrhage … thrombosis…. Aneurysms .

5- history …… -Note the presence of deviation of the eye 5- history …… -Note the presence of deviation of the eye. -There may be an abnormal head posture to compensate for the inability of the eye to move in a particular direction - diplopia - if present family hisory - medical history or systemic diseases

6- examination and investigation …. -determination of acuity - determination of any refractive error . -detection of any abnormality in eye movement (H shape). sixth nerve palsy results in failure of abduction of the eye. fourth nerve palsy results in defective depression of the eye when attempted in adduction . A third nerve palsy results in: 1) failure of adduction , elevation and depression of the eye 2) ptosis 3) in some cases dilated pupil due to involvement of the autonomic fibers - careful examination of the eyes ( dilated funds view)

7- treatment : - treatment according to the cause ( An isolated nerve palsy is often related to coexistent systemic disease. If a posterior communicating aneurysm is suspected, the patient must be sent for neurosurgical review and angiography.  The most common cause of palsy is microvascular disease of a peripheral cranial nerve, associated with diabetes or hypertension. The nerve function often recovers over months. Especially in old ones  disease in the cavernous sinus may also be the cause of multiple nerve palsies such as 3rd , 4th and 6th) - Diplopia can be helped by fitting prisms to the patient ’ s glasses, which realign the retinal images. -If eye movements fail to improve spontaneously then surgical intervention may be required..

Disease of the extraocular muscles thyroid eye disease (Grave’s disease) Myasthenia gravis : ** long-term neuromuscular disease that leads to varying degrees of skeletal muscle weakness.[1] The most commonly affected muscles are those of the eyes, face, and swallowing ** Pathogenesis >> caused by the development of antibodies to the acetylcholine receptors of striated muscle. It affects females more than males 15-50 y. **Some 40% of patients may show involvement of the extraocular muscles only.

**Symptoms and signs: Variation in clinical signs and symptoms over days to weeks, with fatigability, is the hallmark of myasthenia . Variable diplopia and variable ptosis may be present **Diagnostic tests : Confirmed by : 1)electromyography or 2) by determining whether an injection of neostigmine or edrophonium (cholinesterase antagonists) temporarily restores normal muscle movement **Treatment: Patients are treated in collaboration with a neurologist , with neostigmine .  Systemic steroids and surgical removal of the thymus