Ergonomic enhancement of a light-guided vocal fold injection device: Addressing usability limitations through usability engineering.

Vocal fold injection procedures demand precise needle placement, yet limited intraoperative visualization creates dependence on practitioner experience. Building on a first-generation light-guided injection system, this study applied iterative usability engineering to address usability limitations. Otolaryngologists (n = 33) participated across three phases: design concept, three formative evaluations, and summative validation. Use-related risks were translated into user interface requirements. The prototype was developed and iteratively refined, with qualitative feedback revealing physical ergonomics and needle-handling as top design priorities. The second-generation device features a portable wireless design with contoured and textured grip surfaces, optimized Y-connector angle, light-intensity control dial, and balanced weight distribution. User satisfaction improved from 3.86 to 4.72 across evaluations, and summative validation (n = 15) demonstrated 100% task completion with one use error. These findings highlight the ergonomic design of handheld medical devices, the challenge of habit-driven use errors, and the significance of iterative usability evaluations.