Ablation of Intraocular Tissue with Fiber-optic Probe–Delivered 266-nm and 213-nm Laser Energy

Abstract

To explore the tissue ablation properties of pulsed 266-nm and 213-nm laser radiation in porcine retina and the potential for 213-nm laser radiation to cut through human trabecular meshwork. Segments of porcine retinas were used, and localized areas of tissue were exposed to 266-nm or 213-nm laser. Human trabecular meshwork from donor eyes was also ablated using pulsed 213-nm laser. Ocular tissue was bathed in fluid to mimic the intraocular environment. Single or multiple pulses at various fluence levels were delivered with a tapered fiber-optic probe. The tissue was then fixed for histologic examination. Ablation depth and extent of damage were measured and related to fluence level and number of pulses applied. Ablation of the inner retina was achieved by single pulses at fluence levels of 0.6 J/cm(2) and higher with 266-nm laser radiation and 0.2 J/cm(2) and higher with 213-nm laser radiation. At the same fluence, ablation depth was greater (P < 0.001) with 213-nm than 266-nm laser, with less collateral damage. Ablation of human trabecular meshwork using 213-nm laser was highly dependent on fluence after exposure to single and multiple pulses, allowing good control of ablation depth. Laser radiation at 213 nm has greater ablation efficiency, less collateral damage, and a more linear dose-response than ablation at 266 nm. Precise removal of human trabecular meshwork was demonstrated using pulsed 213-nm laser radiation.