Ocular muscle and eyelid surgery in thyroid-associated orbitopathy.

Abstract

The aim of ocular muscle surgery in Graves' disease is to determine how an optimal normalization of ocular motility disorders - diplopia, compensatory head posture, eyelid dispositions - can be achieved. The results of ocular muscle surgery of fibrotic ocular muscles allow the following conclusions to be drawn. Correcting the motility disorder can be precisely dosed by recessing only one fibrotic ocular muscle with a strabismic angle of up to 15 degrees. This leads to reproducible and dependable results, with a dose-effect coefficient independent of the initial strabismus angle. Indications as to the amount of surgery and which side should be varied according to horizontal an vertical deviations, and are also dependent on the compensatory head posture. Improvement of the binocular visual field is possible in nearly all cases. Over corrections 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 status should have been stable for at least six months. Postoperatively, within the first few days, an insufficient correction should be expected, however this should not lead to premature revision of the amount of surgery. The surgery of the vertical rectus muscles influences the eyelid position. The upper lid retraction is improved with surgery on the vertical extraocular muscle and depends on prior upper lid motility. In contrast, an increase in lower lid retraction is not dependent on an inferior rectus recession. The results permit a precise series of steps to be drawn up in Graves' disease regarding surgical indications, proportionally correcting each side, and the dosage of ocular muscle operations.