Surgery for Optic Nerve Injury: Should Nerve Sheath Incision Supplement Osseous Decompression?

ABSTRACT Objective: To evaluate the benefits and risks of performing an optic nerve sheath incision to supplement standard osseous optic canal decompression for traumatic optic neuropathy. Methods: Before-after analysis of 57 cases undergoing optic nerve decompression at a tertiary referral centre from 1988–2006. Fifty-five cases had adequate post surgical follow-up for evaluation for improvement. Group A (N = 35) had decompression of the osseous optic canal and surgical slitting of the optic nerve sheath; Group B (N = 22) had osseous decompression alone. The groups were comparable for age, injury severity, and injury-surgery interval. Main outcome measure: Percentage visual improvement, which was calculated by conversion of the pre- and post-intervention visual acuity measurements to the logarithm of the minimum angle of resolution (logMAR) scale. Results: No significant recovery was noted in subjects with persistent complete blindness (PL-ve vision). In subjects with residual pre-op vision, the quantum of recovery was greater in Group A than in Group B (46% and 33% respectively, P = 0.10). The difference was especially evident in subjects with no optic canal/posterior orbit fracture (P = 0.07). Three cases with the sheath incision developed transient CSF rhinorrhea in the initial experience, but this was subsequently alleviated with modification of surgical technique. Conclusion: The addition of optic nerve sheath incision to osseous decompression may improve recovery in optic nerve injury, especially in subjects without optic canal fracture.