title: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  The addition of optic nerve sheath incision to osseous decompression may improve recovery in optic nerve injury, especially in subjects without optic canal fracture.
authors.affiliation: Department of Otolaryngology and Head-Neck Surgery, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Alok
authors.initials: A
authors.lastname: Thaker
authors.forename: Dev Ashish
authors.initials: DA
authors.lastname: Tandon
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Mahapatra