Femtosecond Laser Photodisruption of Primate Trabecular Meshwork: An Ex Vivo Study

Abstract

The femtosecond laser has been realized as an advantageous tool for micromachining, and the feasibility of employing it for surgical procedures has been investigated. A prior study demonstrated dose-dependent femtosecond laser photodisruption of peripheral corneal tissue through a gonioscopic lens in enucleated porcine eyes and of the trabecular meshwork (TM) in human corneoscleral rim tissues, with little collateral damage. The present study was undertaken to extend these efforts to ex vivo primate eyes. Photodisruption of the TM in enucleated baboon eyes and human donor eyes was performed with a gonioscopic lens and a custom femtosecond laser ablation delivery system. Laser ablation was executed with a Titanium:Sapphire laser (800-nm wavelength), focused with a 0.15-NA lens, with the following settings: pulse duration, 45 fs; pulse energy, 60 to 480 microJ; pulse repetition rate, 1 kHz, total exposure time, 0.001 to 0.3 seconds. The laser lesions were evaluated by two-photon microscopy. Laser-induced lesions were consistently observed in the TM of the baboon and human eyes and visualized by two-photon microscopy. These oblique, trough-shaped lesions, which did not penetrate the juxtacanalicular region, had sharp edges and showed no evidence of thermal coagulation. The dimensions of the lesion increased linearly with both pulse energy and exposure time. The present study demonstrates that laser ablation of the TM ab interno in ex vivo primate eyes is feasible by a custom femtosecond laser ablation system with a gonioscopic lens.