Predicting postoperative paradoxical diplopia

Anomalous retinal correspondence (ARC) is the mechanism that functionally links noncorresponding retinal elements in the visual cortex to allow single binocular vision in the strabismic patient. Surgical correction of the strabismus in patients with ARC may lead to temporary paradoxical diplopia. ARC may be diagnosed prior to surgery by revealing a faulty spatial orientation of the fovea of the deviating eye through a fovea-to-fovea test, or by detecting the presence of a pseudo-fovea via a fovea-to-periphery test of retinal correspondence. This retrospective study was designed to determine which type of test, fovea-to-fovea or fovea-to-periphery, is most effective at predicting postoperative diplopia in adult patients with long-standing strabismus and ARC. Of the thirteen patients enrolled in the study, 62% had temporary postoperative diplopia. One hundred percent of the diplopic patients demonstrated ARC on fovea-to-fovea tests preoperatively. Patients with ARC on fovea-to-periphery tests were just as likely to be diplopic as not after surgery. Performance on any one sensory test did not correlate well with results on any other test. Fovea-to-fovea tests are more effective than fovea-to-periphery tests at detecting ARC and predicting the likelihood of postoperative diplopia in an adult patient.