[Endocrine orbitopathy. Interventions on the external eye muscles].

Eye muscle surgery in Graves' disease is conducted to normalize eye motility disorders-diplopia, abnormal head posture, eyelid malposition. A review of the literature to determine the results of eye muscle surgery on the fibrotic eye muscles indicated the following: Correction of the motility disorder can be done precisely by recessing only one fibrotic eye muscle with a strabismus angle of up to 15; this leads to reproducible and dependable results, with a dose-effect coefficient independent of the initial strabismus angle. Indications vary as to how much to do as well as which side, dependent on whether the deviation is horizontal or vertical and whether the head posture is abnormal. Improvement of the fusional visual field is possible in nearly all cases. Hypercorrections occur more often when the muscle is not directly fixed at the sclera but adjusted on the following day. The time factor is important both before and after the operation: before the operation, the motility situation should have been stable for at least 6 months; postoperatively, a correction should be expected, which is not yet sufficient in the first few days; this should not lead to premature revision. Surgery on the vertical rectus muscles influences eyelid position: upper-lid retraction is improved and depends on the previous upper-lid motility; in contrast, an increase in lower-lid retraction is not dependent on recession of the inferior rectus. The results reported permit a precise series of steps to be drawn up as regards indication, the proportion of correction of each side, and eye muscle operations in Graves' disease.