Some physiological considerations upon the efficacy of the retroequatorial myopexia
Introduction: The efficacy of eye muscle surgery is thought to be mainly mechanical regardless of any specific methods. Cüppers´ Faden-procedure e.g. is explained to be effective by fixating the muscle artificially more proximal to the sclera thus creating a shorter part of free muscle not touching the sclera tangentially. However, other than mechanical influence may cause the final effect as palisade endings and other proprioceptive receptors are located in the muscle belly and more proximal to the muscle´s origin. Therefore, surgical slings through the muscle rim at 11-13 mm on each side are altering a rather sensitive area, in particular the transition between the first and the second third of the muscle, where these structures are starting to emerge.
Methods: 13 patients underwent a modified Faden-Operation without scleral fixation (marginalization), 22 eye muscles being recessed and slung on both sides to 1/3 of their width at a distance of 11-13 mm from the insertion. A mere marginalization without any additional recession was performed 3 times.
Results: A significant improvement in terms of almost alignment or at least a remarkable reduction of some huge angles was established in any of the patients including those cases without additional recession. Postoperative motility resembled to the Faden-induced restrictions on adduction, thus being milder.
Discussion: Not only are the results remarkable and longstanding but even improving in some cases after a latency of 2-8 weeks, postoperatively. This is in contradiction to other authors (1,2), who did not take into account a possible physiological aspect of the issue. Proprioceptors as palisade endings and different muscle spindles (3,4,5) may play a much more important role in influencing the surgically altered muscle reaction than it has been considered until now.
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