Accommodative Esotropia 

Updated: Jul 26, 2016
Author: Chris Noyes, MD, FAAFP; Chief Editor: Hampton Roy, Sr, MD 

Overview

Background

Strabismus is misalignment of the eyes such that both eyes are not simultaneously directed at the same object. Esotropia is a type of strabismus characterized by an inward deviation of one eye relative to the other eye. Accommodative esotropia (refractive accommodative esotropia) is an esodeviation due to normal accommodation in uncorrected hyperopia. The AC/A (accommodative convergence/accommodation) ratio gives the relationship between the amount of convergence (in-turning of the eyes) that is generated by a given amount of accommodation (focusing effort). Amblyopia is reduced visual acuity due to an abnormal visual experience early in life.[1]

Pathophysiology

A patient with uncorrected hyperopia must accommodate to clear a blurred retinal image. This process of accommodation will stimulate convergence and strain fusional divergence. When fusional divergence is overcome, the eyes cross. The patient with uncorrected hyperopia can see either a single blurred image or a double image in which one image is clear and one image is blurred. Over time, the blurred image can be suppressed; fixation can alternate; or, more commonly, amblyopia can occur.

Epidemiology

Race

No racial predilection exists.

Sex

No sex predilection exists.

Age

This condition usually presents by the age of 2 years.

 

Presentation

History

Parents of the patient may notice an inward or upward deviation of one eye relative to the other eye. The patient may see either a single blurred image or a double image in which one image is clear and one image is blurred. Family history of strabismus or related diseases is common. The age of onset of strabismus should be noted.

Physical

Carefully examine visual acuity in a manner appropriate for the patient's age. For patients younger than 1 year, visual acuity is measured by objective means. For patients aged 1-3 years, subjective methods, such as Allen cards, 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. The patient usually will have hyperopia in the range of +3.00 to +10.00 diopters.

Determine stereo acuity using polarized glasses and Titmus test or 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, it is possible to perform the alternate cover test. 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 true accommodative esotropia, the angle of deviation is the same when measured at distance and near fixation and usually is 20-40 prism diopters.

Measure AC/A. If this ratio is high, then the deviation measured at near will be significantly greater than that at distance. In pure accommodative esotropia, the AC/A ratio should be normal; 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 the optic nerve.

Perform cycloplegic refraction on all children by using the retinoscope and loose lenses. Cycloplegia is achieved with Mydriacyl 1% if the patient is younger than 1 year; it is achieved with Cyclogyl 1% if the patient is 1 year or older.

 

DDx

 

Treatment

Medical Care

Prescription of the full amount of hyperopic correction provides adequate treatment for refractive (accommodative) esotropia in 75% of cases.[2, 3]

Anticholinesterase drops or ointments in patients with a normal AC/A ratio are not as effective as glasses.

In cases of amblyopia, early treatment by patching the normal eye is the mainstay of treatment.

Surgical Care

Surgery may be required if the esodeviation becomes refractory to optical treatment. Surgery often is needed when treatment is delayed.[4]

Surgical treatment typically entails recession or weakening of the inward-pulling medial rectus muscle in each eye. In cases involving amblyopia, surgery can be limited to only the amblyopic eye by performing a recession of the medial rectus and a resection or strengthening of the lateral rectus.

Surgery is performed for the nonaccommodative component only. The operation is not intended to discontinue use of glasses.

 

Medication

Medication Summary

There are no medications for this condition.

 

Follow-up

Further Outpatient Care

Patients who are treated for amblyopia should be seen at 1- to 4-month intervals depending on their age.

Stable patients are typically seen every 6 months.

Cycloplegic refraction is repeated at least annually and any time esotropia worsens.

Prognosis

Permanent vision loss can occur if strabismus and amblyopia are not treated before patients are 4-6 years.

Early treatment of amblyopia may result in improved vision, leading to a better prognosis for binocular vision development and a more stable alignment for surgery if required.[5]

With patients aged 4-5 years, one can attempt to reduce the strength of the hyperopic correction to enhance fusional divergence and to maximize visual acuity.

If glasses are worn faithfully and fusional patterns are established, many patients with refractive esotropia can maintain straight eyes without wearing glasses by the time they are teenagers.