SEARCH RESULTS FOR: Strabismus

Strabismus

$Strabismus: Pathogenesis and clinical findings Microvascular dysfunction, trauma, or compression of oculomotor nerve Oculomotor nerve palsy: Dysfunction of the nerve innervating the superior rectus (elevation), inferior rectus (depression), medial rectus (adduction), and inferior oblique muscles (excyclotorsion) Thyroid eye disease (see Thyroid Eye Disease slide for pathogenesis) Inflammatory processes Thickening & fibrosis of extraocular muscles, most commonly the inferior rectus muscle (functions to rotate the eye and depress the gaze) Brown syndrome (congenital) Anomalous interaction between the trochlea and superior oblique muscle tendon Restriction of normal movement of the superior oblique tendon through the trochlea Trochlear palsy (Dysfunction of the trochlear nerve (CN IV)) Weakness of the superior oblique muscle innervated by CN IV (responsible for depression of the gaze and incyclotorsion & rotation of the eye) Near reflex: convergence (eyes adduct), accommodati on (thickening of the lens) & miosis (constriction of the pupil) Excessive accommodation in hyperopic (farsighted) eyes Over-activation of near reflex Accommodative esotropia Aneurysm, infection, iatrogenic injury to cranial nerve (CN) VI Abducens palsy: ocular motor paralysis Failure of CN VI to develop normally in utero Duane syndrome: congenital malformation of CN VI Congenital fibrosis of the extraocular muscles (CFEOM) Restrictive global paralysis of the extraocular muscles that control the movements of the eye Phenotype CFEOM2 Phenotype CFEOM1 & 3 Dysfunction of the abducens nerve (CN VI: innervates the ipsilateral lateral rectus muscle which abducts the eye [turns it laterally]) Orbital fracture (fracture of the orbital floor) Intraorbital contents (inferior rectus muscle and/or surrounding tissue) herniate through the fractured site & are entrapped Idiopathic infantile esotropia Intermittent exotropia Unclear process Exotropia: affected eye is rotated laterally Esotropia: affected eye is rotated medially Hypotropia: affected eye is rotated downward compared to non-affected eye Hypertropia: affected eye is rotated upward compared to non-affected eye Horizontal Strabismus Two different images are received by the eye that cannot be fused together Visual cortex suppresses the input from one eye in order to avoid having diplopia Amblyopia/lazy eye: visual cortex diminishes neural inputs from the corresponding cortical areas of affected eye ↓ Spatial awareness Vertical Strabismus Binocular diplopia: double vision when both eyes are open, and absent when either eye is closed Atypical alignment of the eye Psychosocial consequences: negative impact to mental health due to social bias or abuse, social anxiety, and difficulties with self-image Authors: Mina Mina Lucy Yang Reviewers: Mao Ding William Stell* * MD at time of publication ↓ Visual acuity ↓ Oculomotor control Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published September 6, 2023 on www.thecalgaryguide.com$