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A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320- µm cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

Chromium-sensitized and thulium- and holmiumdoped YAG lasers (THC:YAG laser) were used to create a nasal bony ostium in the area of the lacrimal sac fossa in four fresh frozen bisected human cadaver heads. The lasers - long pulsed (300 milliseconds), compact, self-contained, and solid state - operate in the near infrared (2.1 urn). The opening was created by passing the 320-micrometer laser fiber across the canalicular system. Pulse energies of 250 to 900 mJ were used with a repetition rate of 5 to 15 pulses per second. Energy levels ranging from 1.25 to 9 W produced a full-thickness bony ostium approximately 3 to 4 mm in diameter. Silicone tubing was then threaded through the superior and inferior canaliculus system in the standard fashion. This technique may simplify conventional dacryocystorhinostomy as well as endonasal laser dacryocystorhinostomy procedures.

A new method to create filtering tracts ab interno or ab externo which may eventually prove useful in eyes with poorly controlled glaucoma is described. Fiberoptics of 200 µm diameter, with either cleaved or 500 µm ball lens tips, were coupled to the output of an argon gas laser emitting a number of radiation lines in the ultraviolet (333 to 363 nm) wavelengths. This system was used to perforate the corneoscleral limbal tissue of enucleated bovine eyes with a small number of laser applications to create a filtering fistula. Corneoscleral limbal perforation with a 200 µm cleaved fiber required 0.6 to 1.1 J total energy, delivered with a laser power of 0.5 W, or greater, for 0.1 second. With a 500 µm ball lens fiber tip a tract of nearly 0.5 mm diameter was created, requiring 5.1 to 10.4 J total energy, delivered with a laser power of 2.0 W, or greater, for at least 0.1 second. The energy required for perforation from the external surface to the anterior chamber was the same as the energy required for ab interno perforation.