Levator Advancement Surgery with or without Lateral Horn Incision: Effect of Lateral Horn Incision for Severe Involutional Blepharoptosis

Background: The lateral portion of the levator aponeurosis transforms into fibrous tissue called the lateral horn. Conventional levator advancement surgery for involutional blepharoptosis preserves the integrity of the lateral horn. The impact of incising the lateral horn has not been thoroughly studied. Methods: Sixty-nine patients who had undergone levator advancement surgery for involutional blepharoptosis between 2020 and 2023 were included in the study. In cases where the levator aponeurosis could not be well advanced during surgery, the authors incised the lateral horn to increase the advancement. The authors then retrospectively reviewed cases with or without the incision. The authors also measured the effect of the incision intraoperatively using a sheet with a scale grid. Results: Lateral horn incisions were performed in 32 of the 69 cases. The preoperative degree of blepharoptosis was significantly more severe in cases that necessitated the incision (margin reflex distance 1, 0.5 mm versus 1.0 mm; P < 0.05). Patients receiving the incision were significantly older than those without (73.4 years versus 61.7 years; P < 0.05). There were no significant differences between the 2 groups in postoperative margin reflex distance 1 (2.8 mm versus 3.0 mm; P = 0.20). Intraoperative measurements revealed that the levator aponeurosis was advanced 4.3 mm more caudally and 3.1 mm more medially as a result of the lateral horn incision. Conclusions: Lateral horn incision is effective in levator advancement surgery for severe involutional blepharoptosis. This technique aids in preventing undercorrection of palpebral fissures, especially in the medial region. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.