Changes in retinal correspondence following surgery for intermittent exotropia

An intermittent exotrope of 54delta had harmonious anomalous correspondence when squinting and normal correspondence when bifoveally fixating. Measures of the angle of deviation (H) and angle of anomaly (A) were made at the first postoperative dressing 6 hr after surgery (H = 8--14delta esotropia, A = 0--54delta exo) and at several times over a 2.5-mo period during which a second operation was performed. The final result was 3delta of exophoria with normal correspondence when fusing and harmonious anomalous correspondence (A = 3delta exo) when fusion was disrupted. The change in angle of anomaly created by the surgery cannot be explained by changes in fusional vergence. Halldén's "sensory-fusion" mechanism, which is based on diplopia resulting from stimulation of disparate retinal points, is more useful in explaining the obtained results.