The accommodative esotropias

Chapter 75 The accommodative esotropias


The most widely accepted classification of accommodative esotropia includes four distinct types:

1. Fully accommodative esotropia (refractive esotropia): those patients in whom the distance and near deviation are equal and the esotropia is caused entirely by uncorrected hypermetropic refractive error. In one study, these patients had a mean age of onset of image years and a mean refractive error of +4.75 D.3 They have a normal accommodative convergence to accommodation (AC/A) ratio and respond to correction of the full cycloplegic refractive error (Figs 75.1 & 75.2).

2. High AC/A ratio accommodative esotropia: those patients who have a significant near–distance disparity in the magnitude of the esotropia, with the deviation being at least 10 prism diopters (PD) more at near than at distance. They have a younger age at presentation (mean 2.7 years old),4 and a lower degree of hypermetropia, than patients with typical fully accommodative or refractive esotropia. They have a normal hyperopic refractive error for age and little or no esotropia in the distance

3. Arguably, the most common form has elements of both of the preceding types. These patients have a significant hypermetropic refractive error and some level of high AC/A ratio that leads to a deviation that is greater at near than distance by at least 10 PD.

4. “Early onset esotropia” or “infantile accommodative esotropia” refers to patients with fully accommodative esotropia presenting at a very early age. They may present with esotropia as early as 6 months of age and typically have very high hypermetropia and are more likely to have inferior oblique ove.raction.


Fig. 75.2 The same girl as in Figure 75.1 4 weeks later wearing her full hyperopic correction. She has a small left esotropia with fixation preference for her right eye. Part-time occlusion therapy of the right eye is begun.

The accommodative convergence/accommodation ratio

The accommodative convergence/accommodation ratio (AC/A) plays an important role in the development, treatment, and prognosis in accommodative esotropia. Patients with a high AC/A ratio present earlier, are more likely to require surgery, and to have a poorer prognosis for long-term binocular vision.5 There are different ways to calculate the AC/A ratio although in clinical practice this is not necessary. A clinical comparison of distance to near deviation is most commonly used to determine whether or not the AC/A ratio is high. Patients can be further classified based on the degree of near–distance disparity:

To calculate the AC/A ratio, either the gradient or heterophoric method can be used. For the gradient method, measure the deviation at a fixed distance while relaxing accommodation by introducing plus lenses as follows:


where p is the power of the lens used, D0 the deviation without lenses, and D1 the deviation with lenses.

In the heterophoric method, near and distance deviations are compared while taking into account the interpupillary distance (IPD) as follows:


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Jun 4, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on The accommodative esotropias

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