title: Endoscopic free electron laser technique development for minimally invasive optic nerve sheath fenestration.
abstract: OBJECTIVE
  This study proposed to develop a technique for efficiently accessing the posterior orbital space using endoscopy and attempted application of free electron laser (FEL) energy, biopsy forceps, electrocautery, and CO(2) insufflation to posterior orbital tissues.
  
  
  METHODS
  Through an inferior transconjunctival incision, access to the posterior orbital space was attempted in 14 eyes of 7 non-survival pigs. FEL energy (6.1 microm, 30 Hz, delivered via 250 microm hollow-glass waveguide), biopsy forceps, and monopolar electrocautery application were endoscopically attempted in the posterior orbit. CO(2) gas insufflation effects were assessed by analyzing arterial blood gases at 30-minute intervals for 1.5 hours.
  
  
  RESULTS
  The posterior orbit was accessed in 13 of 14 eyes, the optic nerve was encountered, and FEL energy was applied in 8 of 14 eyes. Use of biopsy forceps and electrocautery were successful. Although ANOVA results for arterial blood gas changes were not statistically significant, visibility was adequate without CO(2) insufflation.
  
  
  CONCLUSIONS
  The posterior orbit was endoscopically accessed and the optic nerve was exposed and successfully treated with FEL energy. CO(2) insufflation did not alter blood gases, but did not further enhance visibility in this study.
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Rohan J
authors.initials: RJ
authors.lastname: Shah
authors.forename: Jin H
authors.initials: JH
authors.lastname: Shen
authors.forename: Karen M
authors.initials: KM
authors.lastname: Joos
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004724:Endoscopy / Q000379:methods*; D053685:Laser Therapy / Q000379:methods*; D009900:Optic Nerve / Q000601:surgery*; D009916:Orbital Diseases / Q000601:surgery*; D013552:Swine; D016896:Treatment Outcome