What is Accommodative Esotropia?
Accommodative esotropia is the crossing or turning in of the eyes due to the over-convergence (crossing) of the eyes with accommodation (focusing of the eyes). Most of these children are moderately hyperopic (farsighted). When the child tries to focus their eyes to see clearly their eyes turn in or cross. This occurs in approximately 2 percent of children. Accommodative esotropia is one of the most common types of strabismus.
What Causes Accommodative Esotropia?
When a child is born their eyes are straight. As they learn focus, their eyes turn in or cross as they accommodate or focus their eyes to clear their vision. This is caused by an over-convergence and insufficient fusional divergence which allows the eyes to turn in. It usually develops in children between ages 2 to 4. There is no difference in females to males or any race predilection.
Contributing Factors for Accommodative Esotropia
Moderate hyperopia which is most likely greater than +2.00.
It tends to run in families but there has not been any genetic component isolated at this time.
An incident such as an illness or trauma may lead to the manifestation of the esotropia but does not directly cause it.
After the symptoms have been controlled in childhood it may return in the forties or fifties.
Diagnosis of Accommodative Esotropia
Usually the parents notice that their child’s are starting to cross which may be intermittent in the beginning but will later become permanent. This is typically noticed around age 2. There are two types of accommodative esotropia:
Refractive Accommodative Esotropia
This characterized by a child with moderate hyperopia and crossed eyes. A cycloplegic refraction (a refraction to determine the eyeglass prescription after instillation of eye drops to paralyze their focusing) is performed and their full hyperopic prescription is placed in their glasses. After wearing their glasses a re-exam is done to confirm that their eyes are straight with the glasses on.
Non-Refractive Accommodative Esotropia
This esotropia is characterized by a high accommodative convergence/ accommodation ratio (AC to A). Refractive errors can be myopic or hyperopic. The esotropia is greater when focusing at near than at distance.
Treatment and Management of Accommodative Esotropia
The primary goal is to return the child’s ocular alignment to normal in order for the child to develop binocular vision and prevent amblyopia (lazy eye or loss of vision).
The primary treatment of accommodative esotropia is for the child to wear the full hyperopic correction. As the child ages the glass prescription can be reduced as long as the eyes remain straight.
If there is a high AC to A ratio then bifocal glasses will be prescribed with the necessary power needed to correct their crossing.
In a small number of cases, the glasses do not correct all the esotropia. This may occur in up to 10 percent. These children will need eye muscle surgery to help straighten their eyes.
Clinical Course and Prognosis
The greatest risk to these children is the development of amblyopia and loss of binocular vision. The earlier the treatment is begun the better the outcome. Follow up will be done on a case by case basis to monitor their vision, check their ocular alignment, and eye glass prescription. These children can have excellent vision in both eyes but the stereopsis levels can vary.