Abstract
Abstract: :
Purpose: Previous studies have shown that a hollow waveguide system could be used to transmit a free electron laser (FEL) for the purpose of an optic nerve sheath fenestration (ONSF) via an endoscope. As with all endoscopic procedures in a closed space, a gas or liquid has been needed to insufflate the explored area to maximize visualization. This study was conducted to evaluate the effectiveness of different media, and systems to maintain a closed system, for endoscopic ONSF’s of live pigs and pig. Methods: An experimental study utilizing an author designed laser delivery system through an endoscope was conducted. Two adult pig cadavers and four live adult pigs had orbital endoscopy performed to develop a method of ONFS with the FEL. A total of eleven orbits were used in the development of the surgical technique. Three different media – sodium hyaluronate, saline, and CO2 – and four different media containment systems were tried and evaluated separately for their ability to increase visualization and their effect on surrounding tissues while maintaining a closed system. Results: Visualization of orbital structures was consistently clearest with CO2. Sodium hyaluronate did not displace the fat and tended to be difficult to contain and saline hydrated the orbital fat. While CO2 was superior, insufflation was difficult without mechanical containment to reduce the flow rate and maintain a consistent view. The most successful CO2 containment system consisted of an adhesive Gabor shield enclosing the entire orbital rim with an ostomy-type sleeve to allow for full range of motion of the endoscope. Conclusions: CO2 was found to be the superior visualization medium for endoscopic ONSF via the FEL. However, due to fears of hypercarbia and raise IOP, an appropriate mechanical containment system is needed to maintain the lowest and most consistent flow rate possible, while maintaining optimal visualization. Additional studies are currently examining techniques to improve its containment.
Keywords: orbit • neuro-ophthalmology: optic nerve • laser