Evaluation of endocrine ophthalmopathy with saccadic eye movements

Horizontal saccades were examined in 25 patients with hyperthyroidism and/or endocrine ophthalmopathy (EOP) using the infrared reflection method. With one exception none had restriction of horizontal eye movements. Conventional saccadic parameters were usually normal. A standardized test for muscle fatigue, however, gave pathological results in all but one of the patients with EOP, and also in three of seven patients with hyperthyroidism but no clinical EOP. In one of the latter the oculographic abnormality disappeared with treatment, while another developed clinical EOP. Performing a saccadic fatigue test seems to be useful for detecting early EOP and especially for monitoring its course.