Abstract
Abstract: :
Purpose: To find out whether or not clinically significant changes of rapid eye movements can be detected in patients with different stages of thyroid associated ophthalmopathy (TAO), and whether saccadic analysis could serve as an additional diagnostic tool in patients with TAO. Methods: Thirty-six patients with TAO and 10 control subjects were investigated. The patients were divided into 4 groups: 1. early mild disease (n=10), 2. early severe disease (n=10), 3. longstanding restrictive disease (n=10), and 4. proven auto-immune thyroid disease without any signs of TAO (n=6). Horizontal and vertical saccades with an amplitude of 10°, 20°, 30° and 40° were recorded binocularly using the induction scleral search coil technique. Two constants of the main sequence were calculated for each eye: the asymptotic maximum velocity (V0) and the steepness of the amplitude dependent change of velocity (α). Repeated measurement analysis of variance was carried out to test for differences between different gaze directions, eyes and groups. Applying V0 and α to the main sequence formula, the average main sequence curves of the different groups were reconstructed. Results: In vertical saccades, the differences between groups and the interaction between groups and up- and down-gaze saccades were significant. Compared to the control group, analysis of the reconstructed main sequence curves showed more pronounced changes for patients of group 3 and 4 than for group 1 and 2. In the control group, up-gaze saccades were faster than down-gaze, the difference increasing with higher velocity. The opposite behaviour was found in the patient groups, the largest differences being detected among the patients without signs of TAO (group 4). In horizontal saccades, significant differences were found between groups but not between ab- and ad-duction. Conclusion: Analysis of the main sequence constants and mathematical reconstruction of the curves appears to be the most sensitive analysis technique for early detection of changes of eye motility. Our present results demonstrate that specific changes of rapid eye movements are induced in all patients with TAO, even in those who do not show clinical signs. Subsequently, saccade analysis may help to early identify those patients who are at risk to develop TAO.
Keywords: 409 eye movements: saccades and pursuits • 327 autoimmune disease • 357 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials