Surgery for optic nerve injury: should nerve sheath incision supplement osseous decompression?

To evaluate the benefits and risks of performing an optic nerve sheath incision to supplement standard osseous optic canal decompression for traumatic optic neuropathy.

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.

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.

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.

The addition of optic nerve sheath incision to osseous decompression may improve recovery in optic nerve injury, especially in subjects without optic canal fracture.