Factors that influence the postoperative upper eyelid position following surgery for involutional blepharoptosis

External levator advancement is commonly performed for involutional blepharoptosis repair; however, it is difficult to predict the postoperative upper eyelid position (UEP) accurately in blepharoptosis surgery. The purpose of this study was to determine the factors that influence postoperative UEP following surgery for involutional blepharoptosis. We retrospectively studied 40 Japanese women (80 eyelids) who underwent bilateral external levator advancement surgery. We used digital analysis software to measure the UEP and the eyebrow position from straight-gaze view photographs. Statistical analysis was performed to determine the correlation between postoperative UEP and related factors, including age, levator function, amount of levator advancement, anatomical fixed position, and preoperative and intraoperative UEP. We also compared UEP changes in mild, moderate, and severe ptosis groups. Levator function affected both preoperative and postoperative UEP. The amount of levator advancement and the anatomical fixation position on the aponeurosis did not affect the postoperative UEP. However, both preoperative (r = 0.49) and intraoperative (r = 0.55) UEPs affected the postoperative UEP. In cases of severe ptosis, there was significant re-drooping after surgery, while in cases with mild ptosis, the intraoperative eyelid position was maintained or slightly elevated. In involutional blepharoptosis, the degree of preoperative and intraoperative UEP contributed to the postoperative eyelid position. These data suggested that the levator muscle function is a major contributing factor in the pathogenesis of involutional blepharoptosis.