Optic nerve sheath fenestration with endoscopic accessory instruments versus the free electron laser (FEL).

Background And 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.

Study Design/materials And 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.