1

Introduction

Traumatic optic neuropathy is a condition commonly associated with blunt trauma to the head or orbit. Indirect traumatic optic neuropathy is the most common mode of injury and occurs from a shock wave transmitted to the optic canal. Direct traumatic optic neuropathy, on the other hand, results from direct trauma to the optic nerve from sharp objects and missiles and their resultant bony fragments. Direct traumatic optic neuropathy is a feared complication of endoscopic sinus surgery with an incidence of 0.5% to 9.3% . We report a case of direct traumatic optic neuropathy after endoscopic orbital decompression with recovery of vision from no light perception (NLP) to 20/20.

2

Case report

A 21-year-old African American woman with Graves’s exophthalmos, normal visual acuity, and normal visual fields underwent bilateral endoscopic orbital decompression for dyscosmesis. At the time of surgery, the surgeon noted a thick lamina papyracea and a paucity of orbital fat resulting in medial rectus muscle exposure. On postoperative day 1, the patient reported blurred vision measured at hand motion OD and 20/30 OS. The right pupil was nonreactive with a 4+ relative afferent papillary defect (RAPD). She had minimal proptosis and normal intraocular pressure, and the optic nerve head appeared normal. Intravenous dexamethasone, 10 mg TID, was initiated. Computed tomographic (CT) scan showed right medial orbital wall decompression with herniation of orbital contents into the nasoethmoid region. A fragment of lamina papyracea was in direct contact with the right optic nerve and medial rectus muscle, and there was enhancement of the optic nerve sheath ( Fig. 1 A and B).

(A and B) Axial and coronal CT shows residual lamina papyracea spicule between the right optic nerve and medial rectus muscle.

Based on imaging results and severe vision loss OD, emergent surgical revision was performed. The bony fragment compressing on the optic nerve was localized through computer-aided surgical navigation and removed, and the ethmoid complex and the orbital floor were further resected to enhance the volume of decompression. Postoperative CT scan confirmed removal of the bony fragment of concern. The patient reported no light perception OD on postoperative day 1. A 1.8 log unit RAPD was measured OD. Intravenous methylprednisolone, 250 mg QID, was initiated. Four days later, the patient could intermittently see light and was discharged on a slow taper of oral prednisone.

Two weeks later, visual acuity was 20/40 OD, the optic nerve remained pink and healthy, but a 2+ RAPD remained. Four weeks later, visual acuity was 20/20 and visual field showed generalized constriction OD. At 4 months, vision was stable at 20/20 OD, there was no red desaturation, and a small RAPD remained.