David R. Lally
BASICS
DESCRIPTION
• Form of strabismus in which an eye deviates inward toward the nose (formerly called “internal strabismus”).
– Comitant esotropia: Angle of strabismus is similar in all gaze positions.
– Can be intermittent or constant.
– Types include accommodative or nonaccommodative, sensory, congenital/infantile non accommodative(see chapter), consecutive after surgery for exotropia, and cyclic
– Rarely associated with ocular myasthenia, or thyroid eye disease.
EPIDEMIOLOGY
Incidence
1 study found incidence of 111.0 (95% confidence interval, 99.9–122.1) per 100,000 patients younger than 19 years of age. (1).
Prevalence
Approximately 2.0% of all children younger than 6 years (1).
RISK FACTORS
• Poor vision in one or both eyes (sensory esotropia).
• Premature birth.
• Cerebral palsy.
• Seizure disorders.
• Developmental delay.
• Hyperopia.
Genetics
• Likely multifactorial (environmental, polygenic).
• Accommodative esotropia: 23% have affected 1st-degree relative, 91% have any affected relative (2).
– 1–7% of orthotropic relatives of patients with esotropia have monofixation syndrome.
– If underlying cause of sensory esotropia then the genetics of that primary disorder may apply although the incidence of esotropia may show variable expression.
GENERAL PREVENTION
• Early correction of significant hyperopia may reduce risk of accommodative esotropia.
– Compliance with hyperopic correction for accommodative esotropia my prevent secondary nonaccommodative esotropia from developing.
– Correction of causes of low vision in one or both eyes.
PATHOPHYSIOLOGY
• Most cases have no known pathophysiology attributed to ocular muscles, orbit or cranial nerves.
– Accommodative esotropia: Increased accommodative effort to overcome hyperopia yields excessive convergence.
ETIOLOGY
• Accommodative esotropia: Etiology related to high hyperopia (3).
– Acute comitant esotropia: Possible gliomas and other tumors, Chiari type 1 malformations, hydrocephalus, thalamic disease, or seizures.
– Sensory esotropia: Intraocular pathology including cataract and retinoblastoma.
COMMONLY ASSOCIATED CONDITIONS
• Amblyopia.
– Refractive error (hyperopia).
– Latent, manifest latent or manifest (sensory esotropia) nystagmus.
– Other developmental delays or neurologic disorders, cerebral palsy.
DIAGNOSIS
HISTORY
• Esotropia may start intermittently and then become constant.
• Frequently noticed by parents in pediatric cases.
– Can present with diplopia in acute cases.
– History of low vision in one or both eyes.
– History of neurologic abnormalities or developmental delay.
– History of prematurity.
PHYSICAL EXAM
• Complete eye examination including cycloplegic refraction (may need atropine for 2–3 days before visit to ensure cycloplegia complete).
– Stereoacuity testing.
– Strabismus evaluation including multiple gaze positions and distance and near (ratio of accommodative convergence to accommodation, AC/A ratio).
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• In suspected ocular myasthenia, consider antiacetylcholine receptor antibody titers.
– In suspected thyroid eye disease, thyroid function studies.
Imaging
• Only done in cases of suspected neurological pathology, consider in cases of acute esotropia or esotropia with other neurologic signs.
– MRI of head and orbits.
Diagnostic Procedures/Other
Consider tensilon test if myasthenia considered.
DIFFERENTIAL DIAGNOSIS
• Pseudoesotropia: Prominent epicanthal folds that yield the appearance of esotropia when no true deviation is present, positive-angle kappa.
– Incomitant esotropia (see chapter).
– Myasthenia gravis.
– Thyroid eye disease.
TREATMENT
MEDICATION
First Line
• Oral steroids or Mestinon specifically for myasthenia.
– Otherwise no medications indicated.
Second Line
Phospholine iodide, an anticholinesterase miotic eye drop, has been used to facilitate accommodation without stimulating convergence.
ADDITIONAL TREATMENT
General Measures
• Glasses or contact lenses for full cycloplegic refraction in cases of accommodative esotropia <4 years old and as tolerated in older children (use of atropine at start of glasses wear may help older child tolerate full hyperopic correction if unable to relax latent hyperopia).
– Bifocal glasses maybe necessary in cases of high AC/A ratio.
Issues for Referral
• Consider neurosurgery or neurology consultation for cases of suspected intracranial pathology or myasthenia, respectively.
– Consider orbital specialist for cases of thyroid eye disease.
Additional Therapies
Occlusive therapy with patches or atropine 1% drops for amblyopia as indicated.
COMPLEMENTARY & ALTERNATIVE THERAPIES
Vision therapy is not indicated.
SURGERY/OTHER PROCEDURES
• Strabismus surgery performed in cases of stable nonaccommodative esotropia after other treatments (e.g., glasses for hyperopia in accommodative esotropia) fail to obtain acceptable ocular alignment.
– Strabismus surgery can be performed on 1 eye (recession/resection) or both eyes (usually bilateral medial rectus recession).
IN-PATIENT CONSIDERATIONS
Initial Stabilization
• Only for cases of intracranial pathology.
– Strabismus usually outpatient surgery.
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
• Follow-up examinations based on findings at each visit.
– For stable accommodative esotropia, follow up every 3–4 months depending on the stability of the esotropia control to check for ocular alignment and vision. Serial re-evaluation in cases of variable esotropia.
Patient Monitoring
• Patient can note diplopia frequency.
– Parents can monitor child’s alignment.
PATIENT EDUCATION
• Important to differentiate issues of vision (amblyopia) from alignment (strabismus).
– In adults with intermittent or variable strabismus, important to know time and frequency.
– Stress importance of glasses wear and in accommodative esotropia that it is “normal” for eye to be esotropic without glasses on.
PROGNOSIS
• Accommodative esotropia: Approximately 1/3 always need hyperopic correction (glasses or contact lenses) for straight eyes, 1/3 “grow out” of need for glasses and maintain straight eyes uncorrected, 1/3 need strabismus surgery for nonaccommodative esotropia.
– Guarded with acute comitant esotropia—depends on etiology.
– In cases of cerebral palsy or developmental delay esotropia may increase over time.
COMPLICATIONS
• Amblyopia.
• Surgery for esotropia can result in under- or overcorrections.
– Strabismus surgery also associated with rare complications including infection, hemorrhage, loss of vision, slipped, or lost muscles.
REFERENCES
1. Louwagie CR, Diehl NN, Greenberg AE, Mohney BG. Is the incidence of infantile esotropia declining? A population-based study from Olmsted County, Minnesota, 1965 to 1994. Arch Ophthalmol 2009;127(2):200–203.
2. Birch EE, Fawcett SL, Morale SE, Weakley DR Jr, Wheaton DH. Risk factors for accommodative esotropia among hypermetropic children. Invest Ophthalmol Vis Sci 2005;46(2):526–529.
3. Campos EC. Why do the eyes cross? A review and discussion of the nature and origin of essential infantile esotropia, microstrabismus, accommodative esotropia, and acute comitant esotropia. J AAPOS 2008;12(4):326–331.
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