Effectiveness of An Intraoperative Lagophthalmos Formula for Levator Resection in Patients With Congenital Ptosis.

Purpose: To evaluate the effectiveness of an intraoperative lagophthalmos formula (IOLF) for levator resection in congenital ptosis and investigate the optimal preoperative conditions for IOLF application.

Methods: This retrospective interventional cohort study evaluated 30 eyelids of 22 patients with congenital ptosis who underwent levator resection using the IOLF to calculate the extent of surgical correction under general anesthesia. Surgical success was defined as margin reflex distance-1 (MRD1)≥3 mm in each eye and a difference of MRD1 1 mm between the eyes at 6 months postoperatively. Logistic regression was performed to investigate the preoperative conditions associated with surgical success.

Results: Among 30 eyelids, 19 had good-to-fair levator function (LF) (≥5 mm) and 11 had poor LF ( 4 mm). The overall success rate was 90.0% (n=27/30), whereas the under-correction rate was 10.0% (n=3/30). The surgical success rate was 100% (n=19/19) in eyelids with LF ≥5 mm and 72.7% (n=8/11) in eyelids with LF 4 mm. Patients with preoperative MRD1≥0 mm (versus MRD1<0 mm, odds ratio=34.5, P =0.0098) or a combination of preoperative MRD1≥0 mm and LF≥5 mm (versus MRD1<0 mm and LF 4 mm, odds ratio=48.0, P =0.0124) more likely had successful surgical outcomes.

Conclusions: Levator resection using the IOLF can provide satisfactory results for congenital ptosis regardless of LF. Preoperative MRD1≥0 mm may be suitable for IOLF application, and the combination of preoperative MRD≥0 mm and LF≥5 mm may be the optimal preoperative condition for IOLF application.