Improvement of divergence insufficiency with treatment of thyroid disease: A case report

ABSTRACT

@#This is a case that showed improvement of divergence insufficiency after treatment of thyroid disease. A 50-year-old man developed horizontal diplopia a few days prior to presentation while driving a car. On ophthalmologic examination, prism and alternate cover test revealed an esotropia of 8 prism diopters (PD) at distance and exophoria of 2 PD at near in the primary position. He did not show limitation on ductions, or any signs of conjunctival injection, ptosis, eyelid edema, lid lag and proptosis. Orbit and brain magnetic resonance (MR) imaging and MR angiography revealed no abnormal findings in the extraocular muscles and brain. Serum free T4 level was normal and thyroid stimulating hormone (TSH) level was slightly low, while increased levels of thyrotropin-binding inhibitory immunoglobulin (TBII) and antithyroid microsomal antibody were detected. He was managed with glasses of 4 PD base-out prisms in both eyes. Two months later, serum free T4 was elevated and TSH was markedly reduced. TBII was highly elevated and thyroid stimulating immunoglobulin was positive. After 3 weeks of antithyroid treatment with methimazole, his diplopia improved, and prism and alternate cover test showing orthotropia at distance and exophoria of 10 PD at near in the primary position. This case highlights the importance of thyroid function tests and TSH receptor antibodies in patients with acute onset of divergence insufficiency. Divergence insufficiency could be improved with antithyroid treatment.