Acute onset concomitant esotropia: sensorial evaluation, prism adaptation test, and surgery planning

Acute acquired concomitant esotropia is a rare form of strabismus that usually presents during infancy or early childhood with diplopia and minimal refractive error. The aim of this study was to evaluate the response to the prism adaptation test in a group of normosensorial patients with acute acquired concomitant esotropia and to determine its predictive value for surgical outcome.

Six patients (median age, 11 .5 years) with acute acquired concomitant esotropia underwent the prism adaptation test by applications of Fresnel press-on and prismatic lenses. The sensorial condition of each patient had been evaluated with theTNO stereopsis test, the Irvine test, Bagolini striated glasses, and the Worth four-dot test during the prism adaptation test, when maximum compensation angle was achieved, and after surgery. In all patients, surgery was performed based on the angle of the squint after the prism adaptation test. Patients were observed 1 day, 3 months, 6 months, and 1 year after surgery.

An increase in the angle of the squint occurred in all patients during prism adaptation. The maximum value was obtained in the same amount of time whether with prisms of increasing power or by direct application of the final value of the prisms. The final prismatic value (target angle) was always the same.

The accuracy of the patients' selection confirmed the existence of highly reproducible compensational movements to the prismatic correction in not only patients with anomalous retinal correspondence but also normosensorial patients. Prism adaptation test results were useful in these patients because of their high predictive value for the surgical treatment.