Optic Nerve Sheath Fenestration in Human Cadavers Using the Free Electron Laser Through an Orbital Endoscope

Abstract

Abstract: : Purpose: Previous studies have shown that the Amide II wavelength (6.45 µm) produced by the free electron laser (FEL) can efficiently create an optic nerve sheath fenestration (ONSF) in rabbits. The FEL has been used to perform ONSF in monkeys and in humans undergoing enucleation. This study was conducted to test an author-designed orbital endoscope delivery system for the FEL in fresh human cadavers. Methods: An experimental study utilizing the FEL laser delivery system through an endoscope was conducted. Two fresh human cadavers had orbital endoscopy performed to develop a method of ONSF with the FEL. An ONSF was performed using the FEL (6.45 µm, 30 Hz, 2-3mJ, 250 µm spot size) through a glass-hollow waveguide introduced through an endoscope in the orbits of two human cadavers. Results: A circular dural window was made using the FEL through a glass-hollow waveguide adapted to the Olympus HYF-XP endoscope in both human cadaver orbits with the FEL. A biopsy forceps was used to extract the dural specimen. Histologic evidence of the ONSF was produced. Conclusions: ONSF using the FEL applied via an endoscope is technically feasible. Additional studies are currently examing techniques to improve introrbital endoscopic laser use.

Keywords: neuro-ophthalmology: optic nerve • orbit • laser