Precise ablation of cholesteatoma using a 445-nm diode laser

In cholesteatoma surgery, precise tissue resection is important, as the diseased tissue needs to be completely removed while preserving the ossicular chain to prevent recurrence and hearing loss. The ability to precisely ablate tissue using a pulsed $$445 nm$$ diode laser operating in single-trigger mode was investigated. Single laser pulses with a duration of $$100 ms$$ were applied with a power ranging from 0.5 to 4 W via a multimode optical fiber. Fiber distance to tissue was varied from 0.5 to 5 mm , and irradiation angles from 20^∘ to 90^∘ . Porcine ear cartilage with 500 μ m remaining perichondrium on top served to represent the human ossicle structure with cholesteatoma. Further ablation experiments were performed on human cholesteatoma and ossicle samples. Ablation craters were measured by optical coherence tomography (OCT), and tissue damage assessed with haematoxylin and eosin (H&E)-stained sections. The ablation depth reached up to 350 μ m when operating at $$4 W$$ power output without causing damage to the underlying cartilage. Laser pulses with $$1 W$$ successfully ablated cholesteatoma, but did not damage the ossicles. The results show that a $$445 nm$$ diode laser pulses can be used to effectively remove cholesteatoma, potentially preserving ossicles and hearing ability.