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H. Nakamura, Y. Liu, T. E. Witt, R. J. Gordon, D. P. Edward; Femtosecond Laser Photodisruption of Primate Trabecular Meshwork: An ex vivo Study. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1226. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The femtosecond (fs) laser is a promising tool for micromachining of biological tissue. Our laboratory has previously demonstrated lesions by fs laser photodisruption, which was created in a dose dependent manner at the peripheral cornea through a gonioscopic lens in enucleated porcine eyes and at the trabecular meshwork (TM) in human corneo-scleral rim tissues, producing little collateral damage. The current study was undertaken to extend our previous efforts to ex vivo primate eyes by performing noninvasive fs laser ablation through a gonioscopic lens.
Three freshly enucleated baboon eyes and a human donor eye were obtained from the Biologic Resources Laboratory and the Illinois Eye Bank, respectively. Baboon and human eyes were treated within 6 hours and 24 hours, respectively. Photodisruption was performed at the TM using a gonioscopic lens and a custom fs laser ablation delivery system. Femtosecond laser ablation was performed using a Titanium Sapphire laser (800 nm wavelength), focused with a 0.15 NA lens, with the following settings: pulse duration: 45fs, pulse energy: 60 - 480µJ, pulse repetition rate: 1 KHz, total exposure time: 0.001-0.3s. The laser treatment process was recorded by real time video, and the lesions were evaluated by two-photon microscopy.
During laser surgery, bubble formation was observed and appeared to be positively related to laser energy and exposure time, as previously reported in porcine eyes. These ablations were consistently observed at the TM of baboon and human eyes by two-photon microscopy. The edges of the lesions were sharp, and there was no evidence of thermal coagulation in both eyes. The extent of the lesion increased linearly with both pulse energy and exposure time in baboon eyes (p<0.01, n= 8 and 14, R2 = 0.868 and 0.719, respectively).
The current study demonstrates that laser ablation at the TM is feasible by a custom fs laser ablation system using a gonioscopic lens in ex vivo primate eyes. Our results indicate the potential of a novel noninvasive glaucoma laser therapy.
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