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Abstract

colleagues 1 have suggested some cases of acquired esotropia that recur after medial rectus recessions are caused by a lateral rectus path anomaly that they refer to as "muscle sag." 1 We find that, as illustrated in the article, it is not unusual to see (and feel) the lateral rectus muscle track toward the floor of the orbit as it courses posteriorly when tension is applied with a muscle hook. This is occasionally so dramatic that we feel compelled to check other landmarks-the inferior oblique insertion, inferotemporal vortex vein and inferior rectus muscle insertion-to assure that the inferior rectus muscle was not isolated by mistake. We see this phenomenon in patients with a variety of strabismus, perhaps most often in exotropia, simply because those are the patients in whom we most frequently have a hook under the lateral rectus muscle. Because recurrent esotropia after surgery for acquired esotropia is likewise not rare, it is hard to know whether the 4 patients selected for also having "muscle sag" are not just a random association. As the authors point out, it would be helpful to know how often recurrent esotropia is associated with this lateral rectus finding and how often patients with this finding have esotropia. The response to myopexy is also not convincing with regard to the authors' proposed mechanism, because it was, in each case, accompanied by lateral rectus resection, which is by itself known to be effective treatment for recurrent esotropia. Myopexy was clearly not definitive treatment in the 1 patient, who initially had myopexy alone but subsequently needed lateral rectus resections when esotropia recurred. The initial response to myopexy in that patient might be taken as evidence that correcting an anomalous muscle path has some effect. Alternatively, consider that a myopexy that displaces the muscle from its natural course, anomalous or not, effectively increases the path length and is functionally similar to a resection (something that should be kept in mind when considering other articles regarding myopexy for muscle path anomalies as well). While certainly a creative explanation, this article does not provide enough evidence to convince us that that this common lateral rectus phenomenon is related to acquired or recurrent esotropia in children.