Posterior superior oblique tenectomy at the scleral insertion for collapse of A-pattern strabismus.

PURPOSE: To evaluate the efficacy of tenectomy of the posterior fibers of the superior oblique tendon at the scleral insertion to reduce A-pattern deviations with mild-to-moderate superior oblique overaction.

METHODS: We retrospectively reviewed 22 consecutive patients with A-pattern strabismus and mild-to-moderate superior oblique overaction on whom posterior tenectomy of the superior oblique at the scleral insertion was performed between January 1988 and August 1994. Nine females and 13 males were included, with an age range of 3 to 36 years (mean 13.0 years).

RESULTS: The average preoperative A-pattern for all patients was 18.0 prism diopters (delta) (10 to 33 delta), and a collapse of 16.1 delta was achieved (P < .000001). The average preoperative A-pattern for esotropic patients was 21.0 delta with an average correction of 18.6 delta. The average preoperative A-pattern for exotropic patients was 16.2 delta with a mean improvement of 14.5 delta. Twenty patients (91%) were postoperatively measured to have 6 delta or less difference between up and downgaze. Follow up ranged from 5.0 to 41.0 months (average, 14.0 months).

CONCLUSIONS: This technique provides the surgeon with a predictable partial superior oblique weakening operation that carries a low risk of induced superior oblique palsy, unwanted cyclotorsion, or head tilt.