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To the Editor: We thank Dr. Mostofavi and colleagues for their valuable comments on our case report.1Erdurmus M. Celebi S. Ozmen S. et al.Isolated lateral rectus muscle involvement as a presenting sign of euthyroid Graves disease.J AAPOS. 2011; 15: 395-397Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar In fact, the authors have already indicated the unusual characteristics of the present case, including euthyroid Graves disease, the absence of eyelid retraction, isolated lateral rectus muscle involvement, unilateral presentation, and exotropia. We do not agree with the authors regarding blepharoptosis. In our opinion, clinical examinations and photographic documentations of the patient did not show eyelid ptosis. Other disease processes that may cause signs similar to the present case may include sarcoidosis, tuberculosis, and idiopathic orbital inflammation. As previously noted,1Erdurmus M. Celebi S. Ozmen S. et al.Isolated lateral rectus muscle involvement as a presenting sign of euthyroid Graves disease.J AAPOS. 2011; 15: 395-397Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar in idiopathic orbital inflammation orbital myositis, for example, occurs from inflammation of the extraocular muscle(s) in the absence of an immune response to the thyroid gland. In the present case however, the lateral rectus muscle showed fusiform enlargement of the muscle belly with sparing of the tendon, in contrast to myositis, where the tendon is typically involved and shows thickening on imaging. We were also able to demonstrate an immune response to the thyroid receptors. In addition to this, the patient's chest X-ray did not show any sign of pulmonary tuberculosis and sarcoidosis. He had no signs or symptoms that suggestive of tuberculosis and sarcoidosis as well. Response to 6 weeks oral steroid therapy without any sign of tuberculosis reactivation excluded the possibility of tuberculosis. Unfortunately, we did not perform the tuberculosis skin test and serum angiotensin-converting enzyme levels to rule out tuberculosis and sarcoidosis, respectively. Thyroid-associated orbitopathy may occur associated with other autoimmune disorders, including myasthenia gravis. In the present case, however, there was no history of muscle weakness and fatigability. Although we did not perform biochemical, electromyographic, and pharmacologic testing, we've ruled out the diagnosis of myasthenia gravis on the basis of the patient's clinical signs and symptoms. The exotropia in the present case is definitely attributable to inflammatory involvement of the lateral rectus muscle, which is unlikely in patients with myasthenia gravis (see Figure 2 in the original case report). The present case was diagnosed as thyroid-associated orbitopathy on the basis of history, physical examination, laboratory data, and imaging studies, including ultrasonography and magnetic resonance imaging. Isolated lateral rectus muscle involvement as a presenting sign of euthyroid Graves diseaseJournal of American Association for Pediatric Ophthalmology and Strabismus {JAAPOS}Vol. 16Issue 2PreviewTo the Editor: We would like to share some thoughts on the case of an isolated enlarged lateral rectus muscle belly attributable to presumed euthyroid orbitopathy reported by Erdurmus and colleagues.1 The authors made the diagnosis of thyroid associated orbitopathy (TAO) on the basis of history, physical examination, laboratory data, and radiography. However, the case described is atypical for TAO in several ways. Eyelid retraction, a finding present in most patients with TAO, was absent in this case. Full-Text PDF