[Studies on the botulinum therapy for esotropia improvement of retinal correspondence]

When botulinum therapy was used for esotropia with abnormal retinal correspondence, the esotropia improved effectively and binocular function recovered. Transient overcorrected deviation appeared in 92% of different cases of retinal correspondence. Patients without binocular function and abnormal retinal correspondence of various types were the subjects of this study. There were 18 congenital esotropes and 12 acquired esotropes. Before treatment, there was normal retinal correspondence > abnormal retinal correspondence (NRC > ARC) in 5 cases, abnormal retinal correspondence > abnormal retinal correspondence (ARC > NRC) in 8 cases, abnormal retinal correspondence (ARC) in 16 cases, and lack of retinal correspondence (LRC) in 1 case and the binocular function was incomplete in all cases. Botulinum toxin (0.25-0.5 U) injected into the medial rectus muscles showed hypertonic action. The dose was adjusted according to the deviation angle. We found some changes in retinal correspondence caused by the botulinum therapy in 24 of the 30 patients (80%). Of these there was NRC in 6, NRC > ARC in 11, and ARC > NRC in 7. Secondary esotropia was found in 92% of the 24 cases. We believe that improvement of retinal correspondence is due to suppression of anomalous retinal areas with the change of the overcorrected deviation after the usual visual direction disappears. Our results suggest that normal retinal correspondence has a relatively wide range of correspondence area.