pediatrics
Strabismus
Etiology of Strabismus
Most strabismus is caused by Refractive error Muscle imbalance Rare causes include Retinoblastoma or other serious ocular defects and neurologic disease. Strabismus may be infantile or acquired. The terminfantilerather thancongenitalis preferred because the presence of true strabismus at birth is uncommon, and the terminfantilepermits inclusion of varieties that develop within the first 6 months of life. The termacquiredincludes varieties that develop after 6 months. for infantile strabismus include family history (1st- or 2nd-degree relative), genetic disorders ( Down Syndrome (Trisomy 21) and Crouzon syndrome), can develop acutely or gradually. Causes of acquired strabismus include Overview of Refractive Error (high hyperopia), tumors (eg, Esotropiais commonly infantile. Infantile esotropia is considered idiopathic, although an anomaly of fusion is the suspected cause. Accommodative esotropia, a common variety of acquired esotropia, develops between 2 years and 4 years of age and is associated with hyperopia. Sensory esotropia occurs when severe visual loss (due to conditions such as cataracts, optic nerve anomalies, or tumors) interferes with the brain’s effort to maintain ocular alignment. Esotropia can be paralytic, so designated because the cause is a Sixth Cranial (Abducens) Nerve Palsy , but it is an uncommon cause. Esotropia can also be a component of a syndrome. Duane syndrome (congenital absence of the abducens nucleus with anomalous innervation of the lateral rectus extraocular muscle by the 3rd [oculomotor] cranial nerve) and Möbius syndrome (anomalies of multiple cranial nerves) are specific examples. is most often intermittent and idiopathic. Less often, exotropia is constant and paralytic, as with infantile exotropia or Third Cranial (Oculomotor) Nerve Disorders . can be paralytic, caused by Fourth Cranial (Trochlear) Nerve Palsy that occurs congenitally or after head trauma or, less commonly, as a result of 3rd cranial nerve palsy. can be restrictive, caused by mechanical restriction of full movement of the globe rather than neurologic interference with eye movement. For example, restrictive hypotropia can result from a blowout fracture of the orbit floor or walls. Less commonly, restrictive hypotropia can be caused by Hypothyroidism in Infants and Children (thyroid eye disease). Third cranial nerve palsy and Brown syndrome (congenital or acquired tightness and restriction of the superior oblique muscle tendon) are other uncommon causes. 