Accommodative esotropia is one of the most common types of strabismus in childhood. The incidence is estimated at 2% of the population. It is usually found in patients with moderate amounts of hyperopia. As the patient accommodates or focuses the eyes, the eyes converge. The over-convergence associated with the accommodation to overcome a hyperopic refractive error can cause a loss of binocular control and lead to the development of esotropia.
Accommodative esotropia is caused by accommodative convergence associated with hyperopia. As infants, the eyes are straight, but as they learn to accommodate to see clearly, the fusional divergence is not adequate and the child develops esotropia.
- Hyperopia (usually greater than +2.00)
- 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
This condition may present anytime from infancy to late childhood, but most often between two and four years of age with no sexual or race predilection. In most cases accommodative esotropia is associated with are moderate hyperopia. Extreme hyperopia may not stimulate convergence and may not manifest strabismus therefore it is more difficult to identify by family and caregivers as the eyes are well aligned, however in this case the vision is blurry and leads to binocular amblyopia.
A patient 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.
Refractive accommodative esotropia consists of under corrected hyperopia with insufficient fusional divergence. To confirm the diagnosis, a cycloplegic refraction must be done and the patient placed in his or her full hyperopic correction. Accommodative esotropia can be confirmed by restoring orthotropia with the hyperopic spectacles.
Non-refractive accommodative esotropia consists of a high accommodative convergence:accommodation (AC/A) ratio. Refractive errors can range from myopia to high hyperopia. Esotropia is greater at near fixation than distance fixation.
This usually presents as an acquired, intermittent esotropia. Parents often describe the eyes being straight at times; however will cross when the child is tired or focusing on something up-close. Although it is initially intermittent, it can quickly become constant. The most common age is around 2 years of age but can present from infancy to later in childhood.
Decompensation of initially fully controlled deviation can occur in some cases, necessitating surgical intervention.
The angle of the esotropia is often between 20 and 40 prism diopters and usually smaller than congenital esotropia
A cycloplegic refraction should be done. 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.
- Esotropia occurs 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.
Diplopia can rarely occur. Patients who are not fully accommodating to avoid esotropia will have blurred vision.
- Decompensated esophoria/intermittent esotropia
- Infantile esotropia
- Acquired non-accommodative esotropia
- Cranial Nerve VI palsy
- Duane Syndrome
The goal of treatment is to restore normal ocular alignment to allow binocular visual development and prevent amblyopia.
Spectacle correction is the initial treatment for accommodative esotropia. Generally, the full cycloplegic correction should be given initially. This can be decreased over time to as long as orthophoria is maintained. Single vision spectacles are used in most cases and have been shown to control the esotropia in two-thirds of cases. Bifocals can be used if the distance fixation is orthophoric but there is more than 10 prism diopters of esotropia at near fixation. The minimum bifocal power that restores normal ocular alignment at near (up to 3.5 diopters) is recommended.
Medical follow up
Due to risk of decompensation and manifest strabismus despite appropriate glasses correction follow up should be done as appropriate on a case-by-case basis monitoring for amblyopia and assessment of ocular alignment and binocular visual development. In older patients with good compliance and stable ocular alignment over time, less frequent follow up is required.
Despite correction of hyperopia with spectacles, some patients will develop a non-accommodative component to the esotropia. Studies estimate this to occur in around 10% of patients.
Surgery is recommended when there is a greater than 10 prism diopters of constant esodeviation despite full refractive correction. This amount of esotropia prevents binocular visual development.
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 hypermetropic correction. After the patient wears the prism for two weeks, 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.
Surgical options are most often a bilateral medial rectus recession or a monocular recess-resect procedure. The amount of surgery recommended is controversial with some recommending operating for the residual esotropia and other surgeons recommending an augmented approach.
The greatest risk is development of amblyopia and loss of binocular visual development. Amblyopia is often associated with accommodative esotropia with or without anisometropia therefore the patients should be monitored closely especially in the amblyopic age. 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.
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.
- Reddy AK, Freeman CH, Paysse EA, Coats DK: A Data-Driven Approach to the Management of Accommodative Esotropia. American Journal of Ophthalmology 148:466-470, 2009.
- Prism Adaptation Research Group. Efficacy of prism adaptation in the surgical management of acquired esotropia. Arch Ophthalmol 1990; 180:1248-1256.
- Ludwig IH, Iberman SP, Thompson HW, Parks MM: Long term study of accommodative esotropia. Trans Am Ophthalmol Soc. 2003:101:155-60.
- Lambert SR: Accommodative esotropia. Ophth Clin North Am 14:425-432, 2001.
- Wilson ME, Bluestein EC, Parks MM: Binocularity in accommodative esotropia. J Pediatric Ophthalmology Strabismus 30:233-236, 1993.