eMedicine Specialties > Ophthalmology > Extraocular Muscles

Esotropia, Acquired

Author: Antonio Pascotto, MD, Consulting Ophthalmologist, Istituto Diagnostico Varelli, Clinica Mediterranea, Napoli, Italy
Coauthor(s): Mauro Fioretto, PhD, Professor and Program Director, Department of Ophthalmology, Ospedale Santo Spirito, Casale Monferrato (AL), Italy; Sergio Claudio Saccà, PhD, Professor of Ophthalmology, Department of Neurological and Visual Sciences, Ospedale San Martino, Italy; Vincenzo Orfeo, MD, Head, Operating Unit, Clinica Mediterranea, Naples, Italy
Contributor Information and Disclosures

Updated: Oct 16, 2006

Introduction

Background

Esotropia is a type of strabismus or eye misalignment. The term is derived from 2 Greek words: ésò, meaning inward, and trépò, meaning turn. In esotropia, the eyes are crossed; that is, while one eye looks straight ahead, the other eye is turned in toward the nose. This inward deviation of the eyes can begin as early as infancy, later in childhood, or even into adulthood.

Acquired esotropia can occur after infancy and is not always responsive to farsighted glasses; because of this, it does not fall into the categories of congenital esotropia or accommodative esotropia, which are described in other articles.

Although acquired esotropia can occur in patients aged 1-8 years, it typically develops in patients aged 2-5 years and appears to be infrequently associated with an underlying disease. With acquired esotropia, the angle of deviation is relatively small, and early surgical correction (when indicated) is more likely to achieve bifoveal fixation for these patients than for those with congenital esotropia.

Pathophysiology

Additional laboratory and clinical research often is required to determine the etiology of the acquired strabismus. Scientists agree that some strabismus cases arise from a primary motor anomaly, while others arise from a primary sensory anomaly. Although different treatment approaches clearly are needed for different conditions, no agreement exists on the details for many conditions.

Frequency

International

Of those children with esotropia, 10.4% of them are diagnosed with acquired esotropia.

Mortality/Morbidity

Organic pathologies have been diagnosed in patients initially presenting with strabismus. In a recent study, 11.52% of patients with strabismus had posterior segment abnormalities. The most common diagnoses included Toxoplasma chorioretinitis, morning glory anomaly, Toxocara retinopathy, retinopathy of prematurity, and Coats disease. The mean age of onset of the deviation was found to be significantly lower in patients with esotropia. No correlation existed between the degree of visual impairment and the direction of deviation. This fact emphasizes the importance of performing a fundus examination in each patient presenting with strabismus.

Race

No racial predilection exists.

Sex

No sexual predilection exists.

Age

The median age of onset for children with acquired esotropia is 31.4 months (range, 8-63 mo), with a mean initial angle of deviation of 24 prism diopters (PD).

Clinical

History

The family of the patient may notice an inward deviation of one eye relative to the other eye. In assessing the patient, also evaluate the following:

• Establish family history of strabismus or related diseases.
• Note age of onset of strabismus. Photographs of patients at different ages often can help to determine if the esotropia was present prior to age 6 months and only recently appreciated by the patient's family versus truly acquired (after age 6 mo).

Physical

• Carefully examine visual acuity in a manner appropriate for the patient's age.
  • For patients too young to subjectively quantify their visual acuity levels, objective methods are used.
  • For patients aged 1-3 years, subjective methods, such as Allen cards, often are used in addition to objective methods.
  • For patients aged 3-5 years, subjective methods, such as Allen cards, tumbling Es, or the letter chart, can be used.
  • For patients older than 5 years, the Snellen alphabet chart almost always can be used.
• Determine stereoacuity using polarized glasses and Randot stereogram.
• Check extraocular movements to ensure that the eye movements are full.
• Measure or estimate the angle of deviation.
  • The easiest method is to evaluate the centration of the corneal light reflex in each eye, while the patient fixes on objects at distance or near.
  • In some cases, performing the alternate cover test is possible. Ask the patient to fix on an object. By alternately covering and uncovering each eye, the examiner can detect a shift in the eye's position with refixation. In esotropia, as an eye is uncovered, it turns out to fixate. In accommodative esotropia, the angle of deviation is often the same when measured at distance and near fixation (usually 20-40 PD), but it can vary depending on the accommodative convergence/accommodation (AC/A) ratio.
• Measure the AC/A ratio.
  • If the AC/A ratio is high, then the deviation measured at near will be significantly greater than that at distance.
  • In true accommodative esotropia, the AC/A ratio should be normal (approximately 4/1-6/1); distance and near measurements should be the same.
• Perform a complete eye examination.
  • Examine the anterior segment to assess the cornea, anterior chamber, and lens.
  • Examine the fundus with both direct and indirect ophthalmoscopes.
  • Note the appearance of the macula and optic nerve.
• Perform cycloplegic refraction on all children by using the retinoscope and trial lenses. Cycloplegia often can be achieved with Mydriacyl 1% if the patient is younger than 1 year; it is achieved with Cyclogyl 1% if the patient is older than 1 year.

Causes

Decompensation of a preexisting phoria or monofixation syndrome appears to be the most common etiology of acquired esotropia. Other possible etiologies include the following:

• Children who have been farsighted and have not worn glasses
• Children who were initially responsive to glasses but later developed additional eye crossing (nonaccommodative esotropia) even with full hyperopic correction
• Heredity
• Abnormalities in pregnancy and delivery
• Arnold-Chiari malformation
• Scleral ectasia in high myopia that can lead to a "downslip" of the lateral rectus muscle relative to the globe, giving this muscle a depressing effect at the cost of its physiological action
• Myopic epikeratophakia
• Neurologic abnormalities
• Deficits of abduction
  • Sixth nerve palsy
  • Sixth nerve pseudo-palsy in children with esotropia with manifest-latent nystagmus
  • Unilateral or bilateral type 1 Duane syndrome
• Heroin detoxification: Eye misalignments can occur during heroin use and heroin detoxification and can cause persisting diplopia (double vision) (Firth, 2005).
• Occult sinus disease: Sinusitis supposedly leads to inflammation and secondary contracture in adjacent extraocular muscles (Ludwig, 2004).

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