Comparison of Free-Beam- and Fiber-Type CO₂ Laser Delivery Systems in Stapes Surgery

A free-beam-type CO₂ laser, which use a micromanipulator mounted on a microscope as the delivery system, has the merit of not being affected by hand tremor at the time of shooting. However, this delivery system has several disadvantages, including a restricted operation range and a risk of incorrect focusing. A fiber-type CO₂ laser uses a hand-held delivery system and has the opposite merits and demerits. We compared the results of stapes surgery with free-beam and fiber type delivery systems.

The study enrolled 36 patients who underwent stapedotomy with free-beam- (n=26) or fiber- (n=10) type CO₂ lasers. The air-bone (AB) gap closure, bone conduction (BC) change, and operating time were evaluated. The AB gap closure was calculated by subtracting the preoperative BC thresholds from the postoperative air conduction thresholds. The BC change was calculated by subtracting the postoperative BC thresholds from the preoperative BC thresholds.

The mean operating time was significantly (p=0.035) shorter in the fiber-type group (72.5±8.2 min) than in the free-beam-type group (80.5±11.4 min). The mean AB gap closure did not differ significantly (p=0.297) between the free-beamand fiber-type groups (5.8±10.1 and 1.4±6.8 dB, respectively). The mean BC change did not differ significantly (p=0.873) between the free-beam- and fiber-type groups (2.4±6.9 and 2.8±5.3 dB, respectively). The hearing outcomes did not differ significantly between the two groups.

Operating times were significantly shorter using the fiber-type CO₂ laser, while hearing outcomes did not differ significantly between the two groups.