Purpose: To report the surgical outcome of superior oblique tendon split lengthening for management of patients with severe type of congenital Brown syndrome. Brown syndrome is characterized by hypotropia in primary position and limitation of elevation in adduction more than −4.

Materials and methods: Fourteen consecutive patients with severe congenital Brown syndrome underwent superior oblique split lengthening surgery (10 mm). The amount of hypotropia in primary gaze and the degree of elevation in adduction were compared before and after the surgery. Any surgical complications were also recorded.

Results: Surgery was performed on 15 eyes in 11 female and 3 male subjects. Mean postoperative follow-up time was 12.93 ± 1.79 months (ranging from 10 to 16 months). Average hypotropia in primary gaze improved from 16.2 ± 5.5 prism diopters (range: 10–25 prism diopters) preoperatively to 5.9 ± 4.0 prism diopters (range: 0–18 prism diopters) postoperatively recorded at final follow-up examination (p < 0.001). The limitation in adduction improved from −7.2 ± 4.5 (range: −6 to −8) preoperatively to −1.8 ± 1.3 (range: zero to −5) postoperatively (p < 0.001). No surgical complications were noted.

Conclusion: Superior oblique split lengthening has a significant effect on reducing primary gaze hypotropia and improving elevation in adduction. This technique should be considered for the treatment of patients with severe congenital Brown syndrome.