Better safe than sorry? Results from an ex-vivo study demonstrate that the thulium fiber laser may cause eye injury without standard protection

Abstract

Introduction: We conducted a study using an ex-vivo porcine model to evaluate whether a thulium fiber laser (TFL) induces ocular injury in the context of inadvertent exposure to the laser beam. Methods: A 365 μm TFL was positioned at a set distance (0 cm, 5 cm, 8 cm, and 10 cm) from a freshly harvested (<12 hours) porcine eyeball and the laser was activated for one second at select laser settings for lithotripsy (0.2 J at 50 Hz, 0.5 J at 20 Hz, and 1 J at 10 Hz) and soft tissue ablation (2 J at 10 Hz, 1 J at 50 Hz). The experiment was repeated with laser safety goggles and prescription eyeglasses. Thermal injury was assessed by histopathological analysis. Results: Without eye protection, corneal injury was observed even at 10 cm away for one lithotripsy setting (1 J at 10 Hz) and both tissue ablation settings. All thermal injuries observed were superficial only, except for at 0 cm distance, where deep-layer injury was observed. Laser safety goggles offered complete protection regardless of setting or distance. Partial protection was demonstrated with prescription glasses: histopathological damage was observed for both soft tissue ablation settings and only at 0 cm for two lithotripsy settings (0.5 J at 20 Hz, 1 J at 10 Hz). Conclusions: The TFL can induce ocular injury at close distances and at higher power settings. The use of laser safety goggles confers complete protection while prescription eyeglasses confer partial protection. Further study is warranted.