Accommodative Esotropia

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Article initiated by:

Krista Heidar, MD

All contributors:

Irina Livshitz, MD, Aaron M. Miller, MD, MBA, FAAP, Alex Kozak, K. David Epley, M.D., Chrysavgi Adamopoulou, MD, Yasser I.Abdullah, MD, Jill Rotruck, MD, S. Grace Prakalapakorn, MD, MPH, Krista Heidar, MD, A. Paula Grigorian, MD

Assigned editor:

Jill Rotruck, MD

Review:

Assigned status Up to Date

 by Jill Rotruck, MD on October 16, 2024.

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Disease Entity

Accommodative esotropia is an inward turning of one or both eyes that occurs with activation of the accommodative reflex. Accommodation is a dynamic process in which the curvature of the eye’s natural lens is temporarily adjusted to improve focus at near or in eyes that are hyperopic (far-sighted). Accommodative convergence describes the normal convergence of the eyes in response to accommodation of the lens. The amount of accommodative convergence relative to the degree of accommodation is called the AC/A ratio. There are two main types of accommodative esotropia: 1) Refractive (normal AC/A ratio) accommodative esotropia caused by uncorrected or under-corrected hyperopia and 2) Non-refractive (high AC/A ratio) accommodative esotropia caused by excessive convergence of the eyes in response to accommodation for near focus, regardless of refractive error. A patient may have both a high AC/A ratio and refractive accommodative esotropia; in this setting, the difference in the degree of esotropia between distance and near is typically ≥10 PD.

Epidemiology

Accommodative esotropia is one of the most common types of strabismus in childhood, accounting for nearly one third of all strabismus patients. The incidence is estimated at 1-2% of the population. There is no sex or race predilection.  Onset is typically between 2 to 4 years of age, but may be seen between 4 months and 7 years of age. Symptoms may also begin around the time of onset of presbyopia.

History

This condition may present anytime from infancy to late childhood, but most often between two and four years of age. Typically, the eyes are straight during infancy and the esotropia will develop as they learn to accommodate for clearer vision. The esotropia is usually initially intermittent, manifesting when the child is tired or focusing at near, but can quickly become constant. Some children may complain of double vision; however, young children will frequently suppress the image from the deviated eye, which can lead to amblyopia. Decompensation of an initially well-controlled deviation can occur in some cases, necessitating a change in refractive correction or surgical intervention.

Risk Factors

• Hyperopia (usually greater than +2.00)
• Anisometropia
• Family History, although no pattern of inheritance or genetic locus has been identified.
• May be preceded by illness or trauma; the illness or trauma doesn’t cause the disorder, but can precipitate its manifestation
• Symptoms can recur around the time of onset of presbyopia

Pathophysiology

For normal AC/A ratio accommodative esotropia, a person with hyperopia must accommodate to clear a blurred image. Accommodation will stimulate convergence. If fusional divergence is insufficient to compensate for this, an esotropia will develop. Most patients have moderate hyperopia (typically ≥2.00 D, average of +4.00 D).

For high AC/A ratio accommodative esotropia, the degree of convergence is excessive for the amount of accommodation needed to focus the eye’s lens for near, even with refractive error corrected. This can occur with any refractive error.

Diagnosis

Refractive accommodative esotropia is diagnosed when the eyes become aligned with hyperopic correction in place. A cycloplegic refraction is typically performed.  

Non-refractive accommodative esotropia is diagnosed when the patient has a high accommodative convergence/ accommodation (AC/A) ratio. Patients may have a high AC/A ratio in addition to refractive accommodative esotropia. A deviation that is only present at near or that has a difference of ≥ 10 prism diopters is consistent with a high AC/A ratio.  

Physical examination

Accommodative esotropias are comitant. For a refractive accommodative esotropia, the angle of deviation is typically between 20 and 40 prism diopters. A cycloplegic refraction should be performed. Most often a mixture of 1% cyclopentolate and 2.5% phenylephrine is used. Atropine can be used when cyclopentolate is ineffective, or to confirm that maximal hyperopic correction has been prescribed. In clinical practice, a difference in deviation between distance and near of ≥ 10 prism diopters (PD) is considered a high AC/A ratio.

The AC/A ratio can be determined by multiple methods, with the gradient method being one of the simplest. Normal is between 3:1 and 5:1.

Gradient method:

AC/A = (D0-D1)/p

Where D0 is the deviation without lenses to relax accommodation, D1 is the deviation with lenses to relax accommodation, and p is the power of the lenses used to relax accommodation (typically +3.00 over the habitual refractive correction).

Signs

• Esotropia, especially when focusing on an accommodative target.
• Moderate hyperopia (usually between +2.00 and +6.50); however, in the subgroups with high AC/A ration, can be myopic.

Symptoms

• Diplopia
• Blurred vision if not able to fully accommodate through hyperopia
• Symptoms related to decreased depth perception (difficulty with stairs, catching, throwing, hand-eye coordination)

Differential diagnosis

• Decompensated esophoria/intermittent esotropia
• Infantile esotropia
• Pseudoesotropia
• Acquired non-accommodative esotropia
• Cranial Nerve VI palsy
• Duane Syndrome

Management

The goal of treatment is to restore normal ocular alignment to allow binocular visual development and prevent amblyopia.

General treatment

Spectacle correction is the initial treatment for accommodative esotropia. The full cycloplegic correction is usually given initially. This can be decreased over time if orthophoria is maintained with less hyperopic correction. Single vision spectacles are used in most cases and have been shown to control the esotropia in two-thirds of cases. Children may kept in their full hyperopic correction during during early vision development to prevent amblyopia or carefully weaned out of their full hyperopic correction, leaving a small esophoria, to help stimulate fusional divergence.

Bifocals may be used if there is only a deviation only at near or if there is a residual deviation at near with hyperopic correction in place. The minimum bifocal power that restores normal ocular alignment at near (up to 3 diopters) is recommended. The benefit of bifocals has been called into question. While bifocals do improve alignment at near when looking through the bifocal, they have been found in retrospective analysis to have a larger near deviation when looking through their distance correction and no improvement in stereopsis compared to accommodative esotropes with high AC:A wearing single vision lenses.

Medical follow up

Due to risk of decompensation, manifest strabismus, and amblyopia even with corrective lenses, ongoing follow-up is recommended to monitor ocular alignment, visual acuity, and binocular visual development. In older patients with good compliance and stable ocular alignment over time, less frequent follow up is required.

Management of partially accommodative esotropia

Surgery

Surgery may be considered when alignment is not satisfactory even with refractive correction in place. About 30% of patients will need surgery in addition to refractive correction. Some patients may have a partially accommodative esotropia, where the deviation improves, but does not resolve with refractive correction. The decision on when to operate is clinician and patient dependent. Greater than 10 prism diopter of constant esodeviation can prevent binocular visual development and is commonly considered an indication to operate. Surgery may also be considered in older patients whose hyperopia has largely normalized but have a persistent deviation without minimal correction.

Some suggest prism adaption with Fresnel prisms prior to surgery. Prism adaption is done by prescribing base-out prism for the residual esotropia after prescribing full hyperopic correction. After the patient wears the prism for a period of time, they are evaluated to see if the esotropia has increased, in which case the prism would be increased. This is continued until the esotropia has stabilized.

Bilateral medial rectus recession and a monocular recess-resect procedure are the primary surgical options. The amount of surgery recommended is controversial with some recommending operating for the residual esotropia and other surgeons recommending an augmented approach. Options for surgical management of high AC/A ratio include augmented recession, operating for the near deviation, slant recessions, combined resection-recession, and traditional or muscle pulley posterior fixation sutures.

Chemodenervation

Chemdenervation with botulinum toxin has been shown to be an effective treatment for partially accommodative esotropia both with and without high AC:A ratio and has been reported to have a decreased risk of consecutive exotropia. Others have reported better results with incisional surgery compared to chemodenervation. A smaller angle of deviation and transient overcorrection are reportedly associated with a higher success rate.

Complications

The greatest risks are development of amblyopia and loss of binocular visual development. Amblyopia is often associated with accommodative esotropia with or without anisometropia warranting close monitoring of children in the amblyopic age range. Amblyopia should be treated promptly when diagnosed. Deterioration of control of esotropia is greater in patients with a high AC/A ratio, earlier age of onset, and amblyopia. Delay in treatment and noncompliance with treatment can result in loss of binocular potential.

Prognosis

Studies have demonstrated binocularity of at least peripheral fusion in around 70% of patients with accommodative esotropia. A high level of stereopsis is maintained in about a quarter of patients and is more likely if their esotropia was treated before it becomes constant and did not require bifocals or surgery. Patients with high hyperopia, high AC/A ratio, and anisometropia are more likely to continue to require refractive correction long-term to maintain alignment.

Additional Resources

• Hull J. Accommodative Esotropia. American Association for Pediatric Ophthalmology & Strabismus. https://aapos.org/viewdocument/accommodative-esotropia Accessed March 28, 2023.