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 (≥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° and 25° upgaze. While all of the patients were asymptomatic, had no exophthalmos, and were euthyroid at the time of theexam, Hertel exophthalmometer readings (mean ± SD) for the patients with GD were significantly higher (P < 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° upgaze, IOP abnormalities occurred in 25% and 13% of patients with GD and HT, respectively. At 25° 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 riot. 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° 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.