Acquired Esotropia 

Updated: Sep 13, 2018
Author: Mauro Fioretto, MD; Chief Editor: Hampton Roy, Sr, MD 

Overview

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. The angle is extremely variable and can exceed 50° with a reduction of exodeviation, even under monocular stimulation. 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. However, an accommodative component may be associated.

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.

Epidemiology

Frequency

International

Of those children with esotropia, 10.4% of them are diagnosed with acquired esotropia.[1]

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).

Prognosis

Binocular sensory function is usually severely compromised by even brief periods of abnormal binocular experience during the first year of life.

Patient Education

The prognosis, as well as advantages and disadvantages of the various modes of treatment, should be discussed with the patient's parents and/or the patient, and a plan should be developed based on this dialogue.

 

Presentation

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).

According to Burian and Miller, acute acquired comitant esotropia can be divided into 3 distinct categories: Type 1 (Swan type) refers to esotropia following the interruption of fusion by a period of monocular occlusion or vision loss 2). Type 2 (Burian-Franceschetti type) has no obvious underlying cause other than physical or psychological stress and often presents with modest hypermetropia and minimal accommodation. Type 3 (Bielschowsky type) has been described in myopic subjects.[2] ​

Physical

Visual Acuity

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. Other methods can also be used, such as preferential looking or visual evoked potentials (VEP).

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.

Stereoacuity

Determine stereoacuity using polarized glasses and Randot stereogram or LANG test or TNO test.

Extraocular Movements

Check extraocular movements to ensure that the eye movements are completely extended, both in monocular and then in binocular vision.

Angle of Deviation

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.

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.

Complete Eye Examination

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.

Cycloplegic Refraction

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[3] :

  • 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).[4]

  • Occult sinus disease: Sinusitis supposedly leads to inflammation and secondary contracture in adjacent extraocular muscles.[5]

 

DDx

 

Workup

Imaging Studies

Neuroimaging studies

Consider neuroimaging studies in the absence of expected findings (eg, hypermetropia) or fusion potential or in the presence of atypical features or neurologic signs.

Children with intracranial disease may have no neurological signs at onset.

CT scanning of the brain may be used to rule out causes of intracranial disease.

Four significant risk factors for intracranial disease have been identified that can guide clinicians when to perform brain imaging:[6]

  • Large esodeviation at distance
  • Recurrence of acute acquired comitant esotropia
  • Neurologic signs (papilledema)
  • Older age at onset (>6 years)

CT scan of orbits

CT scanning of orbits is performed with axial and coronal views in 3-mm cuts to evaluate the following:

  • Evaluation of fractures

  • Assessment of potential extraocular muscle entrapment

  • Presence of orbital mass

Chest radiography

Chest radiography is used for the following:

  • Lung nodules suggestive of lung carcinoma

  • May identify suspicious breast lesion

CT scan of neck/thorax/abdomen

This is used to evaluate for systemic malignancy.

B-scan ultrasonography

This is performed upon any doubt of globe integrity.

Radiographic imaging studies

Radiographic imaging studies (eg, MRI of brain and brainstem) are used if neurologic signs or craniofacial anomalies are present.

Other Tests

Bagolini striated glasses test

Most tests for fusion, suppression, and Anomalous Retinal Correspondence (ARC) create artificial viewing circumstances. Normally, the visual environment is not that of a red filter in front of one eye or a combination of red-green filters; separately viewed slides in illuminated tubes are nothing more than a laboratory analysis of retinal correspondence.

The striated glasses popularized by Bagolini allow the patient to view the normal visual environment with a faint reference line placed on the background viewed by each eye. The reference line for each eye is placed at right angles by arranging the glasses in the trial frame so that the striations before the right eye and the left eye are perpendicular to each other. For example, the striations are placed at 135° in the trial frame in front of the right eye and at 45° in front of the left eye. The patient views a fixation light at any distance chosen by the examiner; ordinary room illumination is maintained. The patient reports on the fixation light and observed streaks extending out into the peripheral field of vision.

The Bagolini striated glasses test requires a degree of maturity that seldom is found in a child younger than 8 years. Describing or drawing the suppression scotoma gap in 1 of the streaks presents great difficulty to the young child.

Esotropia

Patients with esotropia of 10 D or more give varied responses, depending on whether they have Normal Retinal Correspondence (NRC), ARC monocular vision, or an absence of binocular vision.

The esotropic patient with NRC sees 2 fixation lights in homonymous diplopia, with a separate streak through each lens and without a break in either streak. Compensating for the esotropic angle with base-out prisms eliminates the diplopic fixation light, and the streaks then intersect at the fixation light.

The patient with ARC and suppression sees 1 fixation light and 2 streaks forming an X; after being questioned, the patient recognizes the suppression scotoma projecting from the nasal retina of the deviated eye as a gap of 5-6° around the fixation light in the streak seen by that eye.

The scotoma can be studied further by removing the striated glass from in front of the fixating eye and slowly rotating the striated glass before the nonfixating eye. As the streak rotates, the gap in the streak around the fixation light persists, beautifully outlining the scotoma for 360°. Furthermore, ARC is made evident by the patient's claim that the streak seen by the deviated eye passes through the fixation light as the patient mentally connects the 2 ends of the gap in this streak. When the light is held in front of the eyes, base-out prism power equal to the esotropic deviation produces crossed diplopia for the fixation light, and each light has its separate streak passing through it.

The patient devoid of single binocular vision sees only 1 light and 1 streak. The patient may claim to see 2 streaks if rapidly alternating but will admit under questioning that the 2 streaks are not perceived simultaneously.

Exotropia

The patient with exotropia of 10 D or more may report NRC with heteronymous diplopia, ARC with suppression, or an absence of binocular vision.

The large profound scotoma of the temporal retina, extending up to the hemiretinal line in the exotropic patient with ARC, prevents all but the best observers from appreciating the extremely peripheral small streak seen outside the suppression scotoma of the deviated eye. Consequently, many exotropic patients report seeing only 1 streak.

Those patients who can detect the small peripheral ends of the streak describe the ends on the axis that coincides with the light, supporting the diagnosis of ARC. Furthermore, base-in prism power placed in front of the eyes that equals the deviation angle creates homonymous diplopia of the fixation light, each image having a separate streak.

 

Treatment

Medical Care

The treatment of the patient with strabismus is based on the underlying cause. In the absence of organic pathology, the treatment plan is formulated based on the interpretation and analysis of the motility examination results and the overall ocular evaluation. Besides the establishment and stabilization of single binocular vision, the significance of normal ocular alignment for the development of a positive self-image and interpersonal eye contact cannot be overemphasized. The goals of treatment may include the following:

  • Obtaining optimal visual acuity in each eye

  • Obtaining and/or improving fusion

  • Obtaining a favorable functional appearance of the alignment of the eyes

Indications for and specific types of treatment need to be individualized for each patient. The treatment of the patient with strabismus may include any or all of the following:

  • Optical correction

  • Added lens power

  • Prisms to eliminate diplopia and to reestablish binocular vision

  • Active orthoptics/vision therapy

  • Amblyopia treatment

  • Pharmacologic agents

  • Extraocular muscle surgery in stable deviations too large to allow spontaneous binocular fusion

  • Chemodenervation

Surgical Care

Prescribing the full hypermetropic correction determined by cycloplegic refraction forms an essential part of initial management. Undercorrection of hyperopia remains a common cause of acquired esotropia. Prism adaptation may be of some value in reducing the frequency of surgical undercorrection in nonaccommodative cases; however, published data, including the results of the Prism Adaptation Study,[7] indicate persistent undercorrection rates of nearly 20%. Other approaches, including modifying dosage tables, operating for the near angle, and augmenting surgery based on the accommodative component, have been proposed and supported by data from a number of small clinical series. A review of published experience shows that augmentation of surgery using a combination of these approaches can provide excellent results.[8]

In patients with acquired esotropia, surgery is indicated when the deviation is greater than 15 PD and stable. If lateral rectus muscle weakness, incomitance, papilledema, or systemic neurologic deficit is evident, neuroimaging studies of the orbits and brain should be performed. Hyperopia greater than +1.50 D or any significant astigmatic refractive error should be treated with glasses prior to performing surgery. Because binocular vision commonly develops before esotropia, surgery is recommended to reestablish binocularity as soon as the pathological underlying causes are eliminated.

Pediatric strabismus surgery is performed under general anesthesia. The presence of any medical condition that precludes anesthetic administration or any life-threatening cause of esotropia (eg, brain tumor) should delay surgery.

Bilateral medial rectus recession is performed most commonly for correction of nonaccommodative esotropia. Initial surgery is designed to correct the entire deviation. Monocular medial rectus recession and lateral rectus resection or unilateral medial rectus recession alone also have been used successfully in this situation.

According to Clark and colleagues, medial rectus pulley posterior fixation, a technique of suturing the pulley to its muscle without scleral sutures, may be as effective as traditional scleral posterior fixation in primary treatment of acquired esotropia with a high AC/A ratio.[9]

Unilateral or bilateral lateral rectus resection is commonly performed for the correction of an eventual residual esotropia after bilateral medial rectus recession. Performing bilateral lateral rectus resection in patients with residual esotropia after bilateral medial rectus recession is considered appropriate because of the high success rate and the provision of a stable alignment during a long-term follow-up period.[10]

Expected surgical results

Clark and colleagues reported good surgical results with bilateral medial rectus recession in 5 of 6 patients with acquired esotropia.[11] Follow-up ranged from 3 months to 3 years. All 5 patients were orthophoric, and 4 of 5 patients had 40 seconds of stereopsis. The sixth patient had a recurrent esotropia of 25 D.

Kittleman and Mazow achieved a functional cure (defined as alignment of the visual axes within 10 PD of orthophoria) in 66% of patients.[12] They achieved a cosmetic cure (defined as alignment of the visual axes within 18 PD of orthophoria) in an additional 17% of patients. Seven patients required reoperation for a horizontal deviation. Some form of fusion was obtained in 85% of these patients, and 52% of patients obtained some degree of stereopsis.

Schoffler and Sturm studied 4 children with acute acquired concomitant esotropia who underwent repeated surgery for the sake of binocularity.[13] In all 4 patients, the final binocularity outcome, after repeated surgery, was high-grade stereopsis (Lang I/II positive). The duration from onset of esotropia to the time of regained stereovision was between 20 and 62 months. High-grade stereoacuity was only achieved after a second surgery in one patient. Their findings support the good binocular potential in patients with this type of acute acquired concomitant estropia. In this study, all 4 patients regained high-grade stereopsis, though they did have a complicated course and long-lasting absence of stereovision.

Consultations

Consult a neurologist/neurosurgeon if neurologic abnormalities (eg, tumor, hydrocephalus) are suspected based on clinical and radiologic findings.

Diet

Dietary treatment is not useful in treating patients with any form of strabismus.

Activity

Physical activity is not useful in treating patients with any form of strabismus. Orthoptics/vision therapy can be very effective in treating patients with some forms of strabismus.

Complications

The most common complication associated with surgery for acquired esotropia is unsatisfactory alignment. Surgery usually is performed on the unoperated horizontal muscles in an effort to reestablish binocular function.

Further Outpatient Care

Regular follow-up care is indicated to monitor the patient's eye alignment.

Relief from the eventual diplopia may be achieved through prismatic correction, and the deviation may then resolve spontaneously. Botulinum toxin or surgical intervention may be necessary in cases that do not resolve. Botulinum toxin must be considered only in patients with spasm contraction of the medial center muscle due to neurogenic spikes. The temporary redaction of these contractions can restore binocular vision, and, eventually, the botulinum toxin can be repeated.

 

Medication

Medication Summary

Drugs are used only to diagnose the disease.

Cycloplegics/Mydriatics

Class Summary

For the diagnosis of acquired esotropia.

Cyclopentolate (Cyclogyl, I-Pentolate)

Blocks muscle of ciliary body and sphincter muscle of iris from responding to cholinergic stimulation, thus causing mydriasis and cycloplegia.

Induces mydriasis in 30-60 min and cycloplegia in 25-75 min. These effects last up to 24 h.

Tropicamide (Mydriacyl, Opticyl, Tropicacyl)

Blocks sphincter muscle of iris and muscle of ciliary body from responding to cholinergic stimulation.