To investigate the effect of vertical deviation change, head tilt and diplopia relief, we performed a minimal amount of inferior oblique recession regardless of the vertical deviation angle and the degree of inferior oblique overaction (IOOA) in superior oblique palsy patients.

We retrospectively analyzed 20 cases of unilateral congenital or acquired superior oblique palsy, which were treated with inferior oblique muscle recession from May 2005, to August 2007. We compared vertical deviation change, head tilt and diplopia relief following surgery. Improvement of head tilt was determined by patient satisfaction measurements. The inferior oblique muscle was attached 4 mm posterior and 2 mm temporal to the lateral border of the inferior rectus muscle insertion in all patients.

The average angle of vertical deviation prior to surgery was 12.4 prism diopters (PD), and the total average correction in the angle of vertical deviation after surgery was 9.6PD. After surgery, head tilt improved in 13 of 16 eyes(81%), and of the four remaining eyes, vertical diplopia was absent.

Although vertical deviation remained after surgery, if patients have enough vertical fusional amplitude, they should be able to overcome the diplopia and the head tilt. Judging from the indication of inferior oblique recession in diplopia and cosmetic problem in superior oblique palsy, a minimal amount of inferior oblique recession is thought to be an effective treatment of unilateral superioroblique palsy with no significant IOOA.