eMedicine Specialties > Ophthalmology > Extraocular Muscles

Exotropia, Congenital

Mounir Bashour, MD, CM, FRCS(C), PhD, FACS, Assistant Professor of Ophthalmology, McGill University; Clinical Assistant Professor of Ophthalmology, Sherbrooke University; Medical Director, Cornea Laser and Lasik MD
C Corina Gerontis, MD, Consulting Staff, Departments of Pediatrics and Ophthalmology, Schneider Children's Hospital/Long Island Jewish Medical Center

Updated: Oct 31, 2008

Introduction

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.

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.

Clinical

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.

Differential Diagnoses

Exotropia, Acquired
Oculomotor Nerve Palsy

Workup

Imaging Studies

Radiographic imaging if neurologic signs are present
Radiographic imaging if craniofacial anomalies are present

Other Tests

Chromosomal studies if any other facial or systemic anomalies are present

Treatment

Medical Care

Prevention of amblyopia

Surgical Care

Bilateral lateral rectus recession
Additional strabismus surgery for oblique muscle dysfunction, dissociated vertical deviation, and large-angle exotropia

Consultations

A pediatric ophthalmology consultation is essential to prevent visual loss (amblyopia), as well as to make the appropriate diagnosis of the etiology of this exotropia.
Genetics evaluation if any other anomalies are present
Neurosurgical evaluation for any craniofacial anomalies

Follow-up

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

Amblyopia prevention by frequent ophthalmic examinations

Complications

Loss of depth perception
Amblyopia (loss of vision)
Neurological consequences if underlying neurologic diagnosis is undetected

Prognosis

Good restoration of binocular vision if detected and treated in time
Vision maintained if amblyopia is detected and treated while still at the critical age of visual development

Patient Education

Familial predisposition for siblings and offspring to develop this or other forms of strabismus
Awareness of potential loss of vision, loss of depth perception, and muscle restriction or shortening
Possible need for amblyopia treatment (patching)
Possible need for repeated surgical procedures

Miscellaneous

Medicolegal Pitfalls

Since there is a high association of neurologic or chromosomal abnormalities, consultation with a pediatric ophthalmologist is essential for the differential diagnosis of isolated strabismus versus systemic involvement.
Any child with possible ocular problems should be seen by a specialist. Eye problems in children may lead to irreversible blindness if not corrected; they do not just go away. Appropriate diagnosis and treatment by a pediatric ophthalmologist prevents possible lifelong visual handicaps.

References

Hunter DG, Kelly JB, Buffenn AN, et al. Long-term outcome of uncomplicated infantile exotropia. J AAPOS. Dec 2001;5(6):352-6. [Medline].
Saunders RA, Trivedi RH. Sensory results after lateral rectus muscle recession for intermittent exotropia operated before two years of age. J AAPOS. Apr 2008;12(2):132-5. [Medline].
Biglan AW, Davis JS, Cheng KP, et al. Infantile exotropia. J Pediatr Ophthalmol Strabismus. Mar-Apr 1996;33(2):79-84. [Medline].
Brodsky MC, Baker RS, Hamed LM. Pediatric Neuro-ophthalmology. 1996.
Hunter DG, Ellis FJ. Prevalence of systemic and ocular disease in infantile exotropia: comparison with infantile esotropia. Ophthalmology. Oct 1999;106(10):1951-6. [Medline].
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. Mar-Apr 2001;38(2):78-82. [Medline].
Mohney BG, Huffaker RK. Common forms of childhood exotropia. Ophthalmology. Nov 2003;110(11):2093-6. [Medline].
von Noorden GK. Binocular Vision and Binocular Motility: Theory and Management of Strabismus. 1996.
Wright KW, Buckley EG, Del Monte MA. Pediatric Ophthalmology and Strabismus. 1995.

Keywords

congenital exotropia, XT, strabismus

Contributor Information and Disclosures

Author

Mounir Bashour, MD, CM, FRCS(C), PhD, FACS, Assistant Professor of Ophthalmology, McGill University; Clinical Assistant Professor of Ophthalmology, Sherbrooke University; Medical Director, Cornea Laser and Lasik MD
Mounir Bashour, MD, CM, FRCS(C), PhD, FACS is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American College of International Physicians, American College of Surgeons, American Medical Association, American Society of Cataract and Refractive Surgery, American Society of Mechanical Engineers, American Society of Ophthalmic Plastic and Reconstructive Surgery, Biomedical Engineering Society, Canadian Medical Association, Canadian Ophthalmological Society, Contact Lens Association of Ophthalmologists, International College of Surgeons US Section, Ontario Medical Association, Quebec Medical Association, and Royal College of Physicians and Surgeons of Canada
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
C Corina Gerontis, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Gerhard W Cibis, MD, Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City
Gerhard W Cibis, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Ophthalmological Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida
J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Pan-American Association of Ophthalmology, Sigma Xi, and Southern Medical Association
Disclosure: Nothing to disclose.

CME Editor

Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.

Further Reading