Irreversible vision loss following split lateral rectus nasal transposition for complete oculomotor nerve palsy

To report a rare case of irreversible vision loss following nasal transposition of the split lateral rectus muscle (NTSLR) in a patient with complete oculomotor nerve palsy (ONP) and outline its clinical implications.

A 12-year-old girl with complete left ONP following gamma knife treatment for an oculomotor nerve schwannoma underwent surgical correction. Preoperative best-corrected visual acuity was 20/15 in the right eye and 20/32 in the left eye, with ≥ 95 prism diopters of exotropia. The left lateral rectus muscle was split and nasally transposed, combined with tenotomies of both ipsilateral oblique muscles. Immediately postoperatively, fundus examination of the left eye was unremarkable; however, within the first postoperative week, the patient developed pain, eyelid swelling, and rapidly declining vision to no light perception in the left eye. Fundus examination of the left eye revealed venous dilation, arterial attenuation, optic disc edema, and macular edema; this later progressed to retinal vessel whitening, optic disc pallor, and the Amalric triangular sign. Magnetic resonance imaging demonstrated posterior displacement of the transposed muscle toward the optic nerve. Suture removal for decompression was proposed; however, the patient and family declined reoperation due to satisfactory cosmetic improvement. Visual function did not recover, resulting in irreversible vision loss.

NTSLR can provide cosmetic benefits, but carries the potential risk of irreversible visual impairment. Careful technique and early evaluation of postoperative symptoms are essential.