[Overcorrection after surgery for unilateral superior oblique palsy].

PURPOSE To study causes of overcorrection after surgery for unilateral oblique superior palsy and treatment options. METHODS Nine cases with overcorrection following surgery for unilateral oblique superior palsy between 2004 and 2006 were identified. Their causes were divided into three types: excessive surgery, bilateral masked palsy and antielevation or adherence syndrome. Treatment was required when there was diplopia in primary and reading positions. A good result was achieved if vertical deviation was inferior to 5 prismatic diopters (PD) in primary position (PP) and 10 PD in oblique diagnostic positions. RESULTS Overcorrection was present in 27.27% of cases. Mean hyperdeviation was 17 PD in PP, 18.4 in oblique positions and 25.22 for the Bielschowsky test. Seven patients underwent two-muscle surgery, and topical anaesthesia was used in eight patients. Overcorrection was diagnosed between 15 days and 6 months following surgery. The etiology was distinct, with 2 patients with bilateral masked palsy, 2 with antielevation or adherence syndrome, and 5 with excessive surgery. Surgical intervention was performed in 6 cases and botulinum toxin used alone or associated with surgery in 4 cases. A good result was obtained in 8 patients. CONCLUSION The incidence of overcorrection was high, with most of these requiring surgical intervention for which good results were obtained.