Saccadic eye movements in Graves' disease

PURPOSE: To describe the saccades made by patients with Graves' disease (GD) and to attempt to distinguish these objectively and quantitatively from the saccades in control subjects.

METHODS: In 12 euthyroid patients with GD, the saccades of both eyes were recorded simultaneously with electromagnetic search coils. Subjects were asked to alternate their gazes between two fixed targets that were 10 degrees, 20 degrees, 30 degrees, or 40 degrees apart along each horizontal or vertical meridian. The data from the patients with GD and those from the similarly recorded group of 12 control subjects were examined in two ways. First, the difference in saccadic sizes between the two eyes was assessed. Second, the saccadic dynamics--that is, the maximum velocity and the saturation constant of the main sequence--were determined for each eye. Repeated measurement analysis of variance was used to test observed differences between the two groups. Finally, through exact logistic regression analysis, classification of the saccades as those of a patient with GD or of a control subject was carried out.

RESULTS: The saccades of patients with GD were generally less conjugate than those of control subjects (P < 0.05). On average, the maximum main sequence velocities in patients with GD were lower than in control subjects (P < 0.05). The saccades of patients with GD were well differentiated from those of control subjects.

CONCLUSIONS: The saccades in GD may differ markedly from normal saccades, and the two can be reliably distinguished.