Types of accommodative esotropia are listed in Table 8-1 and discussed in the following sections.
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. Because of uncorrected hyperopia, the patient must accommodate to focus the retinal image. Accommodation is accompanied by the other components of the near reflex, 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 approximately the same at distance and near fixation and is generally between 20Δ and 30Δ. Patients with refractive accommodative esotropia have an average of +4.00 D of hyperopia.
High AC/A ratio accommodative esotropia
Patients with a high accommodative convergence/accommodation (AC/A) ratio (see Chapter 7) have an excessive convergence response for the amount of accommodation required to focus while wearing their full cycloplegic correction. In this form of esotropia, the deviation is present only at near or is much larger at near.
The refractive error in high AC/A ratio accommodative esotropia (also called nonrefractive accommodative esotropia) averages +2.25 D. However, this esotropia can occur in patients with a normal level of hyperopia or high hyperopia, with emmetropia, or even with myopia.
Partially accommodative esotropia
Patients with partially accommodative esotropia show reduction in the angle of esotropia when wearing glasses but have a residual esotropia despite provision of the full hyperopic correction. This is more likely to occur if there is a long delay in refractive correction. In some cases, partially accommodative esotropia results from decompensation of a pure refractive accommodative esotropia; in other instances, an initial nonaccommodative esotropia subsequently develops an accommodative component.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.