Case Report the Muscle Loss in the Intra Operative Strabismus Surgery

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A lost muscle is one of the most devastating complications that a strabismus surgeon can face in the intra-operative period. Rectus muscles can be lost due to trauma or surgery, including sinus surgery, strabismus surgery, and other ocular surgeries. A lost medial rectus muscle is usually expected in the presence of an overcorrection after exotropia surgery or under correction after exotropia (XT) surgery, resulting in limited duction in the field of action of the muscle. If not treated, a lost muscle will lead to consecutive strabismus, diplopia, and a large limitation of eye movement in the direction of the lost muscle.

A 31 years old man, native of Sao Luis, was referred to the strabismus service due to XT complaints ever since the age of 10, in addition low vision in the right eye. On ophthalmological examination was verified best-corrected visual acuity 0.05/1.0; with preference for the left eye. Concerning extrinsic eye muscles presented XT 25^ concomitant. On monocular rotation tests we found +2 right lateral rectus with ametropic in both eyes. Bio microscopy and funduscopy unaltered in both eyes. The surgical plan was 6.0 mm right medial rectus (MR) resection and a 5.0 mm withdrawal of the right lateral rectus. Due to its friability and lack of support for suturing, the right MR muscle was lost during surgery. Therefore, a transposition of superior rectus to the MR was performed, using a technique similar to that of Jensen’s. The post-operative results after a month were XT 40 (on Hirschberg test) and -2 right medial rectus on monocular rotation tests, besides of normal bio microscopy and funduscopic evaluations (Figure 1).

Upon six months of post-operative, the patient presented concomitant XT 25^ and 12 of right hypertropia (on Krimsky test) and -2 right MR on monocular rotation. One year after the first surgery, a second approach was done with the initial plan being. It was receded right lateral rectus 12.0mm plus 1.0mm anterior dislocation of the right lower oblique ahead of the right inferior rectus (peribulbar). However, due to the increased risk of anterior chamber ischemia, a triple marginal myotomy was performed on the right lateral rectus including anterior dislocation right lower oblique (1.0mm ahead of the right inferior rectus edge) and innervation (recede of the left lateral rectus 8.0 mm). On the seventh post-operative day, the patient presented XT 12^ with right hypertropia 10^, monocular rotation tests showed -2 and -3 right MR and -2 right lateral rectus. Three months after the second intervention, the patient displayed good healing, right hypertropia 15ˆ, and -2 right lateral rectus and -2 right MR (Figure 2), monocular rotation tests with the patient now being discharged.