Intraoperative lagophthalmos formula for levator resection in congenital ptosis

To calculate a regression formula for intraoperative lagophthalmos to determine the amount of correction in levator resection for mild to moderate congenital ptosis.

This retrospective study included 38 eyelids from 28 consecutive children with congenital ptosis with levator function of 4 mm or better who showed satisfactory surgical outcomes defined as postoperative margin reflex distance-1 (MRD1) ≥3 mm in each eye and difference in MRD1 ≤1 mm between eyes at 6 months after levator resection. We investigated whether the degree of intraoperative lagophthalmos measured by calliper correlated with the preoperative values of MRD1, levator function and age. A stepwise multiple regression analysis was performed with intraoperative lagophthalmos as the dependent variable.

The mean intraoperative lagophthalmos was 7.4±0.9 mm (range, 6-10 mm). The intraoperative lagophthalmos was found to have a statistically significant negative correlation with preoperative MRD1 (r =0.55, p<0.0001) and levator function (r =0.53, p<0.0001), respectively. A stepwise multiple regression analysis resulted in the following regression formula: Intraoperative lagophthalmos=9.08 - 0.48×Preoperative MRD1 - 0.26×Levator function (r =0.60, p<0.0001).

Intraoperative lagophthalmos in patients with satisfactory surgical outcome correlated negatively with both preoperative MRD1 and levator function and accounting for both variables resulted in a stronger correlation than either variable alone. Surgeons would be able to calculate the amount of surgical correction using this formula of intraoperative lagophthalmos, which could lead to a satisfactory surgical outcome in levator resection for congenital ptosis.