controlled, prospective, multicenter study. Strabismus. 2005;13(4):169–199.

Accommodative Esotropia

Accommodative esotropia is defined as a convergent deviation of the eyes associated with activation of the accommodative reflex. All accommodative esodeviations are acquired and have the following characteristics:

onset typically between 6 months and 7 years of age, averaging 2½ years of age (can be as early as age 4 months)

usually intermittent at onset, becoming constant often hereditary

sometimes precipitated by trauma or illness frequently associated with amblyopia

diplopia possible (especially with onset at an older age) but usually disappears with development of a facultative suppression scotoma in the deviating eye

Types of accommodative esotropia are listed in Table 8-1 and discussed below.

Pathogenesis and Types of Accommodative Esotropia

Refractive accommodative esotropia

The mechanism of refractive accommodative esotropia involves 3 factors: uncorrected hyperopia, accommodative convergence, and insufficient fusional divergence. Uncorrected hyperopia forces the patient to accommodate to focus the retinal image. With accommodation come the other components of the near triad, namely convergence and miosis. If the patient’s fusional divergence mechanism is insufficient to compensate for the increased convergence tonus, esotropia results. The angle of esotropia is generally between 20Δ and 30Δ and approximately equal at distance and near fixation. Patients with refractive accommodative esotropia have an average of +4.00 D of hyperopia.

High accommodative convergence/accommodation ratio esotropia

In patients with a high accommodative convergence/accommodation (AC/A) ratio, excess convergence tonus for the amount of accommodation required to focus is present when the proper full cycloplegic refraction is used. In this entity, the deviation is present only at near or is much larger at near.

The refractive error in high AC/A esotropia averages +2.25 D. However, this form of esotropia can occur in patients with high or normal degrees of hyperopia, emmetropia, or even myopia.

Partially accommodative esotropia

Patients with partially accommodative esotropia show a reduction in the angle of esotropia when wearing glasses but have a residual esotropia despite treatment of amblyopia and provision of the full hyperopic correction. This is more likely to occur if there is a long delay in refractive correction. Sometimes, partially accommodative esotropia results from decompensation of a pure refractive accommodative esotropia; in other instances, an initial nonacccommodative esotropia subsequently develops an accommodative component.

Evaluation

Vision of the 2 eyes can be equal, or amblyopia can be present. Versions and ductions may be normal, or overelevation in adduction or dissociated strabismus (discussed in Chapter 11) may be present. The deviation should be measured using an accommodative target at distance and at near. Alternate cover

testing on initial examination typically reveals an intermittent comitant esotropia that is larger at near than at distance.

Management

Refractive accommodative esotropia

Treatment of refractive accommodative esotropia consists of correction of the full amount of hyperopia, as determined under cycloplegia. Significant delay in initiating treatment following the onset of the esotropia increases the likelihood that a portion of the esodeviation will fail to respond to spectacle correction. If binocular fusion is maintained, the refractive correction can later be decreased to 1.00–2.00 D less than the full cycloplegic refraction. This is thought to possibly aid in emmetropization. Amblyopia, if present, may respond to spectacle correction alone, but treatment with occlusion or penalization may be needed if the amblyopia persists after a period of spectacle wear.

Parents must understand not only that full-time wear of the glasses is important but also that the refractive correction can only help control the strabismus, not cure it. The esotropia, without glasses, may increase initially after the correction is worn. Discussing these issues with parents at the time the prescription is given is helpful.

Strabismus surgery may be required when a patient with presumed refractive accommodative esotropia fails to achieve an ocular alignment within the fusion range (8Δ–10Δ) with correction (partially accommodative esotropia). The ophthalmologist should recheck the cycloplegic refraction before proceeding with surgery in order to rule out latent uncorrected hyperopia. Refractive surgery, though still deemed experimental for this condition, can also be considered for older patients who continue to need refractive correction to maintain good ocular alignment.

Brugnoli de Pagano OM, Pagano GL. LASIK for treatment of refractive accommodative esotropia. Ophthalmology. 2012;119(1):159–163.

High AC/A esotropia

A high AC/A ratio can be managed optically, pharmacologically, or surgically; it can also be observed.

Bifocals. Plus spectacle lenses for hyperopia reduce accommodation and therefore reduce accommodative convergence. Bifocals further reduce or eliminate the need to accommodate for near fixation. If bifocals are employed, they should initially be prescribed in the executive or 35mm flat-top style with the lowest plus power needed (up to +3.00 D) to achieve ocular alignment at near fixation without cycloplegia. The top of the segment should bisect the pupil, and the vertical height of the bifocal should not exceed that of the distance portion of the lens. Detailed instructions concerning the bifocal should be given to the optician. Progressive bifocal lenses have been used successfully in older children who know how to properly use bifocal spectacles. If progressive bifocals are used, they should be fitted higher than they are in adult lenses (at about 4 mm). An ideal response to bifocal glasses is restoration of normal binocular function (fusion and stereopsis) at both distance and near fixation. An acceptable response is fusion at distance with less than 10Δ of residual esotropia through the bifocal at near (signifying the potential for fusion). While some children improve spontaneously with time, others can be slowly weaned from bifocals. The process of reducing the bifocal power in 0.50–1.00 D steps can be started at about age 7 or 8 and should be completed by age 10–12 years. If a child cannot be weaned from bifocals, surgery can be considered.

Long-acting cholinesterase inhibitors. Long-acting cholinesterase inhibitors (eg, echothiophate