Femtosecond Laser Photodisruption of Porcine Anterior Chamber Angle: an Ex Vivo Study

Abstract

The femtosecond laser is a promising tool for the micromachining of biological tissues. The current study investigated the feasibility of noninvasive glaucoma therapy by femtosecond laser ablation in enucleated porcine eyes by delivering the laser energy through a gonioscopic lens. Freshly enucleated porcine eyes were kept in Optisol GS solution (Bausch & Lomb, Rochester, NY) at 4 degrees C for up to 48 hours. Photodisruption was attempted at the peripheral inner surface of the cornea using a gonioscopic lens and a custom femtosecond laser ablation system. Femtosecond laser ablation was performed using a Ti:Sapphire laser (800-nm wavelength) focused with a 0.15 numerical aperture lens. The laser treatment process was recorded by real time video and the lesions were examined histologically. During laser surgery, bubble formation was observed and appeared to be positively related to laser energy and exposure time. When examined histologically, areas of ablation were consistently observed at the peripheral inner surface of the cornea. The extent of the lesion increased nonlinearly with both pulse energy and exposure time, showing saturation at high energy and long times. For a given energy dose, fewer pulses of high energy were more effective than many low energy pulses. The current study demonstrates that laser ablation at the anterior chamber angle is feasible by a femtosecond laser ablation system using a gonioscopic lens in ex vivo eyes. The results indicate the potential of a novel noninvasive glaucoma laser therapy.