title: Optic nerve sheath fenestration with endoscopic accessory instruments versus the free electron laser (FEL).
abstract: OBJECTIVE
  The free electron laser (FEL) can efficiently produce an optic nerve sheath fenestration using an endoscopic approach. To develop a surgical protocol, this study compared effectiveness of available accessory endoscopic instruments to endoscopic FEL delivery effectiveness in producing optic nerve sheath fenestrations.
  
  
  METHODS
  An endoscope was used to perform optic nerve sheath fenestrations on goat optic nerves. Accessory endoscopic instruments and glass-hollow waveguides (250 and 320 microm in diameter) were inserted into the instrument channel for comparison. FEL energy (6.45 microm, 30 Hz) was delivered to the tissue through the waveguides and histological analysis was performed.
  
  
  RESULTS
  The endoscopic instruments alone were unable to incise the optic nerve sheath. The FEL successfully incised the sheath and the biopsy forceps extricated the circular flap.
  
  
  CONCLUSIONS
  Endoscopic optic nerve sheath fenestration using FEL energy followed by biopsy forceps for sheath extrication produced good results, thereby creating a feasible protocol for optic nerve sheath fenestration.
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University, Nashville, Tennessee 37232, USA. karen.joos@vanderbilt.edu
authors.forename: Karen M
authors.initials: KM
authors.lastname: Joos
authors.forename: Rohan J
authors.initials: RJ
authors.lastname: Shah
authors.forename: Richard D
authors.initials: RD
authors.lastname: Robinson
authors.forename: Jin H
authors.initials: JH
authors.lastname: Shen
mesh_terms: D000818:Animals; D004583:Electrons; D019723:Endoscopes; D004867:Equipment Design / Q000295:instrumentation; D005123:Eye / Q000294:innervation; D006041:Goats; D053685:Laser Therapy / Q000295:instrumentation*; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation; D023421:Models, Animal; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation; D009900:Optic Nerve / Q000528:radiation effects* / Q000601:surgery*; D013524:Surgical Flaps