Novel microsphere chain fiber tips for use in mid-infrared ophthalmic laser surgery

Abstract

Ophthalmic surgery may benefit from the use of more precise fiber delivery systems for laser surgery. In this study, chains of sapphire microspheres integrated into the distal tip of a hollow waveguide are used for preliminary mid-infrared, Erbium:YAG laser ablation studies in contact mode with ophthalmic tissues, ex vivo. The combination of the Er:YAG laser's short optical penetration depth and small spot diameters achieved with this novel fiber probe may provide more precise tissue removal. One, three, and five microsphere chain structures were assembled and compared, resulting in spot diameters of 67, 32, and 30 μm, respectively. Single laser pulses of 0.1 mJ energy and 75 μs duration produced craters with average widths of 44, 30, and 17 μm and depths of 26, 10, and 8 μm, for one, three, and five sphere structures, respectively. Chains of microspheres produced spatial filtering of the multimode Er:YAG laser beam and fiber, thus providing spot diameters not otherwise available for precise tissue ablation using conventional fiber delivery systems. With further probe development, this novel approach to mid-IR laser ablation may provide an alternative to mechanical tools for ultra-precise surgical dissection and removal of ophthalmic tissues.