We report a patient with strabismus associated with thyroid ophthalmopathy whose condition changed remarkably for 6 years of a natural course.

A 69-year-old woman with Graves' disease presented with diplopia in April 1999. On examination, she showed left hypotropia of 50 prism diopters (Δ) accompanied by supraduction limitation and lid lag in the left eye. She was diagnosed with strabismus associated with thyroid ophthalmopathy and was observed without any intervention. In October 2000, her left hypotropia decreased to 16Δ, and esotropia of 14Δ developed. Both eyes showed limitation of supraduction, and the left eye showed limitation of abduction. In December 2003, the esotropia increased to 35Δ, and the direction of vertical strabismus changed to 40Δ of right hypotropia. Supraduction limitation of the right eye and abduction restriction of both eyes increased, and infraduction limitation of the left eye developed. In April 2005, esotropia increased to 75Δ, and the amount of right hypotropia was 35Δ. The abduction limitation of both eyes increased.

The natural course of strabismus associated with thyroid ophthalmopathy can show continuous and remarkable changes.