Lateral rectus sag and recurrent esotropia in children

Abstract

Purpose-To describe the clinical and intraoperative findings of an anatomic abnormality in children that resembles sagging eye syndrome documented in older adults and that led to recurrent esotropia after surgery. Methods-We reviewed records of 4 patients with substantial recurrent esotropia after bilateral medial rectus recession who required subsequent surgery combining lateral rectus resection with correction of the anatomic abnormality affecting the lateral rectus path. Binocular alignment was sequentially analyzed. Results-Three young patients (2-3 years of age) presented with acquired esotropia but minimal cycloplegic refractive error. The fourth patient (14 years of age) initially had moderate hyperopia and partially accommodative esotropia, but subsequently developed marked bilateral overelevation in adduction. In all patients, esotropia recurred within 5 Δ of preoperative deviation after bilateral medial rectus recession. Surgical exposure demonstrated that bilateral lateral rectus paths were inferiorly displaced more than one-half tendon width from their normal paths near the globe's equator, despite normal scleral insertions. Equatorial myopexy and lateral rectus resection resulted in stable esotropia correction.

Lateral rectus sag and recurrent esotropia in children

“…Fundamental to their criticism is the assertion that abnormalities in lateral rectus path, particularly inferior displacement, are relatively common findings at strabismus surgery and should not be considered to cause recurrent esotropia. Our imaging research, both the initial definition of normal extraocular muscle pulley locations 1 and subsequent analyses of hundreds of normal patients recruited as controls for other studies, has consistently demonstrated that extraocular muscle paths are highly stereotypical in people without strabismus. Contrary to the letter's assertion, the much higher prevalence of muscle path abnormalities in strabismic patients undergoing surgery supports-not contradicts-our hypothesis that muscle path disorders impair ocular motility and thus contribute to strabismus.…”

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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.

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Reply

“…From geometry, the abnormal force due to abnormal lateral rectus path is proportional to the magnitude of lateral rectus path displacement. 5 Analogous to a misaligned tire pulling a vehicle toward the roadside, muscle path displacements can be counteracted by applying corrective forces until the abnormal forces become too great or a "second hit" occurs to overwhelm corrective mechanisms and manifest strabismus. Thus, the hypothesis that extraocular muscle pulleys support normal ocular motility by simplifying neurological control of binocular eye movements 6 is supported, not contradicted, by the frequent occurrence of extraocular muscle path abnormalities in patients who have abnormal motility.…”