To evaluate the incidence and course of widening of palpebral fissure after unilateral lateral rectus muscle recession.

The palpebral fissure width (PFW) was measured in 20 patients with intermittent exotropia before unilateral rectus muscle recession and 1 week, 1 month and 6 months after the surgery.

The amount of recession was from 7.5 to 9.0 (mean 8.37 ± 0.51) mm. More than 0.6 mm of change in PFW after surgery was defined as the significant change. The significant change was observed in 10 patients (50%) after 1 week, 7 patients (35%) after 1 month and 7 patients (35%) after 6 months after the surgery. The amount of recession was significantly greater in the group with significant change (8.60 ± 0.39 mm) than the group without significant change (8.15 ± 0.53 mm) ( p < 0.05).

Thirty five percent of the patients showed palpebral fissure widening lasts at least 6 months after unilateral lateral rectus muscle recession. We think it is necessary to notice patients about the possible change in palpebral fissure width before strabismus surgery. And we believe that more cosmetically satisfactory outcome would be resulted if surgeons consider eyelid condition when they are planning strabismus surgery.