The Pulsed Electron Avalanche Knife in Human Vitreoretinal Surgery; A Status Report

Abstract

Abstract: : Purpose: The Pulsed Electron Avalanche Knife (PEAK) is an electrically driven plasma-mediated microsurgical cutting tool that underwent safety analysis in a multi-center international trial. Methods: Between July 2001, and June 2002, a total 26 patients were treated with the PEAK in the United States, Mexico, and Germany. Patients ranged in age from 28 to 80 with a mean of 59 and consisted of 13 males, 13 females, 12 right eyes and 14 left eyes. Of these 26 patients, 11 had PDR and seven PVR. 8 underwent treatment for central retinal vein occlusion by the creation of chorioretinal anastomosis. The safety and efficacy of four specific maneuvers were evaluated and compared with that of conventional instrumentation; (1) transection of transvitreal membranes, (2) dissection of epiretinal fibroglial membranes, (3) dissection of epiretinal fibrovascular membranes, and (4) circumferential retinotomy. Fineness of cut, ergonomics and illumination were graded on an ordinal scale, including monitoring for unintended thermal and mechanical adverse events at the level of the retina, pigment epithelium and choroid. Results: Procedures performed included dissection of fibroglial or fibrovascular membrane in 14 instances, circumferential retinotomy in 6 instances, and chorioretinal anastomosis in 8 instances. Procedure settings varied between 0.1 and 2.0 mJ corresponding to a 30% - 100% power setting. The PEAK knife was judged to be safe and effective, particularly with a bi-manual approach including forceps in one hand. However, axial flow from the probe tip was judged to be partially responsible for the production of unintended remote effects. As a result, a blade electrode was developed, capable of side cutting thus eliminating the problem of tissue bridges and flow associated with original point electrode. Additionally, coagulation capability was added and a new pulse structure was developed for cutting of tougher tissue (PEAK-fc). Conclusions: Initial human clinical experience with the PEAK prototype identified areas of enhanced performance, and also opportunities for refinement of the probe and power supply that should prove useful in the ultimate introduction of PEAK cutting into clinical practice.

Keywords: retinal detachment • vitreoretinal surgery