# Lateral Rectus Muscle Resection for New-Onset Esotropia Following Medial Orbital Wall Decompression in Thyroid Eye Disease

## TL;DR

This study shows that lateral rectus muscle resection is effective in treating esotropia after orbital decompression in thyroid eye disease patients.

## Contribution

The study identifies factors influencing success in correcting esotropia after orbital wall decompression in thyroid eye disease.

## Key findings

- 18 out of 20 patients had successful surgical outcomes with reduced esodeviation.
- Factors like dysthyroid optic neuropathy and resection amounts correlated with improved results.

## Abstract

Background and Objectives: The purpose of this study was to evaluate the outcome of lateral rectus (LR) muscle resection for new-onset or worsening esotropia after medial orbital wall decompression in patients with thyroid eye disease. Materials and Methods: This retrospective observational study included 20 patients. Preoperative and postoperative measurements of ocular deviation angles and fields of binocular single vision (BSV) were performed one day before and three months after surgery. Surgical success was defined as postoperative horizontal ocular deviation ≤ 5° and BSV including the primary position. Factors influencing a reduction in the esodeviation angle were analyzed using univariate and multivariate linear regression analyses. Results: Eighteen patients (90.0%) were deemed as successful surgical cases. The esodeviation angle decreased from 19.4 ± 11.2° to 1.0 ± 2.6°. In multivariate analysis, a reduction in the esodeviation angle was correlated with the presence of dysthyroid optic neuropathy (p = 0.027), amounts of LR muscle resection in mild eyes (p = 0.014), and amounts of additional medial rectus muscle recession in severe eyes (p < 0.001). Conclusions: LR muscle resection showed a high success rate in correcting new-onset or worsening esotropia which developed after medial orbital wall decompression. Several factors influencing a reduction in the esodeviation angle were found.