Congenital Exotropia

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Background

The term congenital exotropia is typically reserved for patients presenting in the first year of life with a large, constant angle.

However, as Hunter et al (2001) state, no published study provides a rationale for this restrictive definition.[1] In their study, they evaluated differences between infants, aged younger than 1 year, with constant exotropia versus intermittent exotropia at presentation.[1] They found that "half of infantile exotropia patients may present with intermittent exotropia, with similar clinical outcomes regardless of presentation."[1] In their study, surgical intervention resulted in successful alignment in most cases.[1] More than half the patients developed measurable stereopsis, but none achieved bifixation.[1]

In a 2008 study of 12 patients with intermittent exotropia treated with bilateral lateral rectus recession, stereoacuity, as seen in the late follow-up period, measured at 40 arcsec in 2 patients, 100 arcsec in 3 patients, 140-400 arcsec in 2 patients, and none in 5 patients.[2]

True congenital exotropia (with a fixed exotropia) is an extremely rare form of strabismus and may occur with systemic disease in as many as 60% of patients. Patients with craniofacial syndromes, ocular albinism, midline defects, and cerebral palsy may present with congenital exotropia.

See related CME at Highlights of the American Association for Pediatric Ophthalmology and Strabismus Annual Meeting.

Pathophysiology

The pathophysiology is unknown, although strabismus does occur in families, suggesting a multifactorial autosomal dominant pattern with incomplete penetrance.

A good recent review of risk factors and genetics in common comitant strabismus can be found here.[3]

Epidemiology

Frequency

United States

Congenital exotropia is extremely rare in the United States.

International

The worldwide incidence of congenital exotropia is unknown.

Mortality/Morbidity

There is a higher incidence of amblyopia in congenital exotropia than in other forms of exotropia.

Race

No known racial predisposition to congenital exotropia exists.

Sex

No known sexual predilection exists.

Age

Congenital exotropia presents in infants younger than 6 months. Children who are born premature are at higher risk of developing strabismus; however, congenital exotropia does not occur at a higher rate in premature children.

History

By definition, children present when they are younger than 12 months with a constant outward deviation of the eyes.

Physical

Unlike other neurologic forms of exotropia, there should be no pupillary or lid involvement. Although craniofacial syndromes can be seen with congenital exotropia, there should be no ptosis or pupillary mydriasis (see Oculomotor Nerve Palsy).

The eyes should appear diverging with no limitation of adduction.

Over time, a preference may occur with one eye used consistently for fixation; then, the other eye will develop amblyopia.

As many as 60% of patients may develop oblique muscle dysfunction, dissociated vertical deviation, and amblyopia. Nystagmus is rare.

Causes

There is a familial predisposition suggestive of an autosomal dominant pattern with incomplete penetrance.

Imaging Studies

Radiographic imaging is indicated if neurologic signs and/or craniofacial anomalies are present.

High-resolution MR imaging enables direct imaging of the ocular motor nerves. In a cohort of 247 consecutive patients with strabismus, Kim et al demonstrated ocular motor nerve abnormalities by high resolution MRI in 98/112 (88%) of patients with congenital or developmental neuropathic strabismus.[4]

Other Tests

Chromosomal studies may be performed if any other facial or systemic anomalies are present.

Medical Care

See the list below:

Surgical Care

See the list below:

Consultations

See the list below:

Further Outpatient Care

A child with any form of strabismus is at risk of losing vision (amblyopia). Since these children present at a nonverbal age, it is imperative that a pediatric ophthalmologist screen and follow the visual status during the critical years of visual development.

Deterrence/Prevention

See the list below:

Complications

See the list below:

Prognosis

See the list below:

Patient Education

See the list below:

Author

Mounir Bashour, MD, PhD, CM, FRCSC, FACS, Assistant Professor of Ophthalmology, McGill University Faculty of Medicine; Clinical Assistant Professor of Ophthalmology, Sherbrooke University; Medical Director, Cornea Laser and Lasik MD

Disclosure: Nothing to disclose.

Coauthor(s)

C Corina Gerontis, MD, Consulting Staff, Departments of Pediatrics and Ophthalmology, Schneider Children's Hospital/Long Island Jewish Medical Center

Disclosure: Nothing to disclose.

Specialty Editors

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy, Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Disclosure: Nothing to disclose.

Additional Contributors

Gerhard W Cibis, MD, Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas School of Medicine

Disclosure: Nothing to disclose.

References

  1. Hunter DG, Kelly JB, Buffenn AN, et al. Long-term outcome of uncomplicated infantile exotropia. J AAPOS. 2001 Dec. 5(6):352-6. [View Abstract]
  2. Saunders RA, Trivedi RH. Sensory results after lateral rectus muscle recession for intermittent exotropia operated before two years of age. J AAPOS. 2008 Apr. 12(2):132-5. [View Abstract]
  3. Maconachie GD, Gottlob I, McLean RJ. Risk factors and genetics in common comitant strabismus: a systematic review of the literature. JAMA Ophthalmol. 2013 Sep. 131(9):1179-86. [View Abstract]
  4. Kim E, Kim JH, Hwang JM, Choi BS, Jung C. MR Imaging of Congenital or Developmental Neuropathic Strabismus: Common and Uncommon Findings. AJNR Am J Neuroradiol. 2012 May 17. [View Abstract]
  5. Biglan AW, Davis JS, Cheng KP, et al. Infantile exotropia. J Pediatr Ophthalmol Strabismus. 1996 Mar-Apr. 33(2):79-84. [View Abstract]
  6. Brodsky MC, Baker RS, Hamed LM. Pediatric Neuro-ophthalmology. 1996.
  7. Hunter DG, Ellis FJ. Prevalence of systemic and ocular disease in infantile exotropia: comparison with infantile esotropia. Ophthalmology. 1999 Oct. 106(10):1951-6. [View Abstract]
  8. Matsuo T, Yamane T, Ohtsuki H. Heredity versus abnormalities in pregnancy and delivery as risk factors for different types of comitant strabismus. J Pediatr Ophthalmol Strabismus. 2001 Mar-Apr. 38(2):78-82. [View Abstract]
  9. Mohney BG, Huffaker RK. Common forms of childhood exotropia. Ophthalmology. 2003 Nov. 110(11):2093-6. [View Abstract]
  10. von Noorden GK. Binocular Vision and Binocular Motility: Theory and Management of Strabismus. 1996.
  11. Wright KW, Buckley EG, Del Monte MA. Pediatric Ophthalmology and Strabismus. 1995.