Efficacy of the double-dose medial rectus muscle recession technique for sagging eye syndrome with esotropia of 10-prism diopters or less at distance.

Purpose: To evaluate the surgical outcomes for small-angle sagging eye syndrome (SES) with a distance horizontal deviation of 10 Δ or less.

Study design: Retrospective observational case series METHODS: Six SES patients (mean age 77.2 ± 5.4 years, 4 men and 2 women) with distance esotropia of 10 Δ or less who underwent medial rectus recession at a single center in Shizuoka, Japan, from January 2020 to December 2023 were studied. Patients with high myopia (axial length ≥ 27 mm, refraction ≤-6 D) were excluded. Preoperative and postoperative alternate prism cover tests, Stereo Fly test (SFT) results, and presence of diplopia were assessed.

Results: The patients underwent unilateral (n = 5) and bilateral (n = 1) medial rectus recession (6.4 ± 0.65 mm and 4.5 mm respectively), with 1 patient undergoing vertical muscle surgery. Preoperative/postoperative deviations (Δ) were distance horizontal +7.3 ± 2.4/-1.5 ± 2.5 (P = 0.035), distance vertical 2.2 ± 2.0/1.0 ± 1.3 (P = 0.42), near horizontal - 0.3 ± 3.2/-8.3 ± 6.4 (P = 0.058), and near vertical 2.0 ± 1.7/1.3 ± 1.8 (P = 0.59). The SFT (log) value was 1.99 ± 0.31/1.73 ± 0.21 (P = 0.056). Three patients experienced transient postoperative diplopia, which resolved over time. The diplopia improved in patients with concurrent vertical muscle surgery or a preoperative vertical deviation of 2 Δ or less (4 patients, 66.7%). However, those with a preoperative vertical deviation of 3 Δ or more (2 patients, 33.3%) required postoperative prism glasses.

Conclusion: Medial rectus recession in small-angle SES with a distance horizontal deviation of 10 Δ or less significantly improved distance horizontal deviation without inducing exotropia at near, with a trend towards improved stereopsis. Patients with a preoperative vertical deviation of 3 Δ or more had persistent postoperative vertical diplopia.