# Eosinophilic Orbital Myositis Superseding Ocular Myasthenia

## TL;DR

A rare case of ocular eosinophilic myositis was diagnosed and successfully treated with glucocorticoids in a patient previously thought to have myasthenia gravis.

## Contribution

This case highlights the importance of tissue biopsy in distinguishing between similar ocular muscle disorders.

## Key findings

- Ocular eosinophilic myositis can present similarly to myasthenia gravis but requires different diagnostic and treatment approaches.
- Glucocorticoid treatment led to significant symptom improvement in the reported case.
- Tissue biopsy is essential for accurate diagnosis of this rare condition.

## Abstract

Various muscles can be involved in idiopathic eosinophilic myositis (IEM), with the ocular muscles being notably affected. Ocular eosinophilic myositis is a rare condition that typically affects the rectus muscles. A tissue biopsy stands as the gold standard for diagnosis. Different subtypes exist based on the extent of eosinophilic infiltration. Limited data is available about treatment, although glucocorticoids have shown successful outcomes. We present the case of a 60-year-old man who, a few years after being diagnosed with ocular myasthenia gravis, was diagnosed through a tissue biopsy with ocular eosinophilic myositis. Treatment with oral glucocorticoids significantly improved his symptoms.