Evidence of extraocular muscle restriction in autoimmune thyroid disease

Patients with Graves' disease lacking eye symptoms frequently have abnormal intraocular pressure (IOP) increases on upward gaze (greater than or equal to 3 mm Hg) indicative of apparent subclinical ophthalmopathy. Because of the close relationship between Graves' disease (GD) and Hashimoto's thyroiditis (HT), we examined 30 patients with a history of HT as well as 26 patients with a history of GD, 4 patients with a history of subacute thyroiditis, 1 patient with a history of silent thyroiditis, and 25 normal subjects for the presence of IOP abnormalities at 15 degrees and 25 degrees upgaze. While all of the patients were asymptomatic, had no exophthalmos, and were euthyroid at the time of the exam, Hertel exophthalmometer readings (mean +/- SD) for the patients with GD were significantly higher (P less than 0.005) than those for either the HT patients or normal subjects (17.1 +/- 2.4 vs. 14.5 +/- 2.3 vs. 14.4 +/- 4.2 mm, respectively). At 15 degrees upgaze, IOP abnormalities occurred in 25% and 13% of patients with GD and HT, respectively. At 25 degrees upgaze, these figures rose to 54% for the GD patients and 37% in HT patients. Only 1 of 25 normal subjects had elevated IOP changes on upgaze, as did the 1 patient with silent thyroiditis, but the patients with subacute thyroiditis did not. These data suggest the frequent presence of extraocular muscle restriction in patients with a history of HT as well as in patients with a history of GD. Maximal detection of these IOP abnormalities requires that patients be examined at 25 degrees upgaze. These data support the belief that the autoimmune bases of both GD and HT are closely linked, at least as manifested by eye muscle involvement.