Evaluation of Holmium:YAG Laser Optical Fibers for Flexible Ureteroscopy using a Relevant Benchtop Model

Materials and Methods. Testing was conducted on single-use and reusable laser fibers in varying sizes – 200μm, 272μm, 365μm, 550μm and 1000μm. Sizes reflect the true core diameter of each fiber. Fixtures for the testing were built for the 200μm, 272μm, 365μm, 550μm fibers simulating the anatomical curvature that the fiber may be subjected to during a procedure (considered the short-term bend radius), as well as the maximum-allowed deflection of the fiber when placed within the working channel of a flexible ureteroscope. A separate fixture was built for the 1000μm fiber simulating the short-term bend radius only, as its core size does not allow for deflection or use within a flexible ureteroscope. Each fiber was placed into its respective fixture, and power outputs were recorded using the HeNe laser JDSU Model 1137 and Lumenis VersaPulse 100W PowerSuite Holmium:YAG laser generator. The SMA-905 connector of each fiber was first connected to the HeNe laser to determine the fiber’s spot size, and the power output was recorded. The fiber was subsequently connected to the Lumenis VersaPulse 100W PowerSuite Holmium:YAG laser generator, and the generator was set to the maximum-allowed power input for each fiber per the Instructions for Use. The power output was then recorded. Further tests were performed on the reusable fibers following cleaving, stripping, cleaning and resterilization, and following transportation and extreme conditioning, and aging. Tests were also carried out on non-sterile laser fibers to evaluate the complete downstream process effect study. To pass testing, the laser fibers had to meet the acceptance criteria of transmitting 80% or greater of the maximum power inputs for both the HeNe and Holmium:YAG lasers. Acceptance criteria also included no known nonconformances reported with either the laser fiber or the laser generator.