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.

Conclusions: Lateral rectus sag in children creates a type of acquired esotropia and overelevation in adduction poorly responsive to standard surgery but correctable with lateral rectus resection and equatorial myopexy that normalizes the lateral rectus path through permanent scleral fixation.

FIG 1.

The right lateral rectus muscle has been isolated through a limbal incision. The insertion, on a Jameson muscle hook, is in the correct temporal anatomic location, but the posterior muscle belly in the equatorial region is inferiorly displaced by one-half tendon width (black arrow). The posterior muscle belly should be centered onto the center of the retractor blade, marked with the white asterisk, to be in the correct temporal location.

FIG 2.

A single 6-0 polyester monofilament suture is placed partial thickness into the equatorial sclera and adjacent superior lateral rectus belly (white arrow) to shift the posterior belly into vertical alignment with its insertion. Now the muscle belly is in the correct temporal location and is centered onto the center of the retractor (white asterisk).

FIG 3.

Using force vector analysis, the abduction force (F_Abduct) equals force of muscle contraction (F) multiplied by the cosine of the angle of displacement (a). For a full tendon width lateral rectus inferior displacement at the globe equator, angle (a) is approximately 51°, resulting in only 62% of muscle force directed toward abduction.