Background: In agreement with the systemic nature of Graves' disease, Graves' ophthalmopathy (GO) presents as a symmetric bilateral eye disease in the vast majority of patients. However, asymmetric involvement of both eyes is frequently observed. We hypothesized that sleeping position might be involved in asymmetric GO; when, for example, the preferred sleeping position is on the right side, retrobulbar pressure might be somewhat higher in the right than in the left orbit, resulting in more severe eye changes in the right eye.
Methods: A prospective study in 75 consecutive untreated patients with GO, in whom eye changes and sleeping position were assessed independent of each other. Criteria for asymmetric eye changes were differences between both eyes in the presence of retrobulbar pain or of > or =1 grade in soft tissue involvement, and/or of > or =2 mm in exophthalmos, and/or > or =8 degrees in elevation. Preferred sleeping position was determined by questionnaire.
Results: All patients had bilateral GO. Eye changes were symmetrical in 50 patients, and asymmetrical in 25 patients based on differences in proptosis and elevation. Sleeping position did not differ between symmetric and asymmetric GO. Preferred sleeping position was on the left side in 23%; on the right side in 31%; and on the back, on the belly, or unknown in 46%. In patients with asymmetric GO, the most affected ("worst") eye was not related to preferred sleeping position on the right or left side.
Conclusion: Slight asymmetry of eye changes between both eyes in patients with bilateral GO is not related to preferred sleeping position on either the right or left side.