[Study of retinal correspondence in esotropia with phase difference haploscope]

There is some concern regarding the evaluated depth of anomalous correspondence, because we often experience paradoxical results. We have already reported that, in intermittent exotropia, we sometimes found dual correspondence with a phase difference haploscope (PDH) reducing the stimulus intensity of either image with a series of neutral density filters. In this study, we analyzed the retinal correspondence in esotropes with the same procedure. 27 esotropes were examined. 11 cases had normal correspondence and 16 cases anomalous correspondence in PDH. All of the 11 normal correspondence cases retained normal correspondence when we reduced the stimulus intensity of either image of fixating eyes or squinting eyes. In the 16 anomalous correspondence cases in PDH, 2 cases showed normal correspondence when the stimulus intensity of the fixating eyes was reduced. On the other hand, 3 cases showed normal correspondence when the stimulus intensity of the squinting eyes was reduced. In fixed heterotropia, both the fovea and the part of the retina of the squinting eye which received the same images as the fovea of the fixating eye (fixating point), were suppressed by the fixating eye. We consider that, in some cases with anomalous retinal correspondence in PDH, when the stimulus intensity of the fixating eyes or the squinting eyes is reduced, the balance of the sensitivity of the foveas and the fixating points of the squinting eyes change, and show normal correspondence.