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Ophthalmology > EXTRAOCULAR MUSCLES
Exotropia, Congenital
Article Last Updated: Jun 28, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 9  
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 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
Coauthor(s):
C Corina Gerontis, MD, Consulting Staff, Departments of Pediatrics and Ophthalmology, Schneider Children's Hospital/Long Island Jewish Medical Center
Editors: Gerhard W Cibis, MD, Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; J James Rowsey, MD, Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Author and Editor Disclosure
Synonyms and related keywords:
congenital exotropia, XT, strabismus
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. In their study, they evaluated differences between infants, aged younger than 1 year, with constant exotropia versus intermittent exotropia at presentation. They found that "half of infantile exotropia patients may present with intermittent exotropia, with similar clinical outcomes regardless of presentation." In their study, surgical intervention resulted in successful alignment in most cases. More than half the patients developed measurable stereopsis, but none achieved bifixation.
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.
Pathophysiology
Pathophysiology is unknown, although strabismus does occur in families, suggesting a multifactorial autosomal dominant pattern with incomplete penetrance.
Frequency
United States
Extremely rare
International
Unknown
Mortality/Morbidity
Higher incidence of amblyopia than other forms of exotropia
Race
No known racial predisposition to congenital exotropia exists.
Sex
No known sexual predilection exists.
Age
This condition presents in infants younger than 6 months. Children that 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
Familial predisposition suggestive of autosomal dominant pattern with incomplete penetrance
Exotropia, Acquired
Oculomotor Nerve Palsy
Other Problems to be Considered
Exotropia of the newborn (This is seen in as many as 70% of newborns. Unlike congenital exotropia, it completely resolves by the sixth month of life.)
Consecutive exotropia (from previous esotropia surgery)
Duane retraction syndrome type II
Lab Studies
- Chromosomal studies if there is any other facial or systemic anomalies
Imaging Studies
- Radiographic imaging if neurologic signs are present
- Radiographic imaging if craniofacial anomalies are present
Medical Care
Surgical Care
- Bilateral lateral rectus recession
- Additional strabismus surgery for oblique muscle dysfunction, dissociated vertical deviation, large angle exotropia
Consultations
- A pediatric ophthalmology consultation is essential. This is to prevent visual loss (amblyopia), as well as make the appropriate diagnosis of the etiology of this exotropia.
- Genetics evaluation if any other anomalies are present
- Neurosurgical evaluation for any craniofacial anomalies
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
Medical/Legal 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.
- Biglan AW, Davis JS, Cheng KP, Pettapiece MC. 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].
- Hunter DG, Kelly JB, Buffenn AN. Long-term outcome of uncomplicated infantile exotropia. J AAPOS. Dec 2001;5(6):352-6. [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].
- Wright KW, Buckley EG, Del Monte MA. Pediatric Ophthalmology and Strabismus. 1995.
- von Noorden GK. Binocular Vision and Binocular Motility: Theory and Management of Strabismus. 1996.
Exotropia, Congenital excerpt Article Last Updated: Jun 28, 2006
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