The role of Whitnall's ligament position in the success of levator resection surgery in congenital ptosis.

Objective: This study aimed to investigate the role of Whitnall's ligament position in the success of levator resection surgery in congenital ptosis.

Methods: It was an interventional case series on patients with congenital ptosis who underwent levator muscle resection in Farabi Eye Hospital (2020-2022). Patients with incomplete follow-up, a history of trauma, poor Bell's phenomenon, previous ocular and lid surgeries, poor levator function (≤ 4mm), and syndromic ptosis or systemic diseases were excluded. During the surgery, several factors, including the distance between Whitnall's ligament and the upper edge of the tarsus (W-distance), the vertical length of the tarsus (T-length), and the amount of levator muscle resection (LMR), were measured. A successful outcome was defined as the inter-eye difference of margin reflex distance-1 (MRD1) ≤ 1 and post-op MRD1 ≥ 3 OR the inter-eye difference of MRD1 ≤ 0.5 with any value of post-op MRD1 in unilateral cases and Postop-MRD1 > 3 in bilateral cases during the 3-months period.

Results: Thirty four eyes of 34 patients were included, and 79.4% of patients achieved successful outcomes. In univariate analysis, Preop-MRD1 and Preop-LF had meaningful negative correlations with the amount of LMR to reach the successful outcome (p < 0.05), which was only meaningful for Preop-LF in multivariable analysis (p < 0.05). Noticeably, W-distance had a significant positive correlation in univariate and multivariable linear regression (p < 0.05).

Conclusions: W-distance can be considered a significant new parameter other than Preop-LF influencing the amount of levator resection needed to achieve success in levator resection surgery.