A new and improved vitreoretinal erbium:YAG laser scalpel: long-term morphologic characteristics of retinal-choroidal injury.

Background and Objective: To report a modified erbium:YAG laser scalpel designed to incise tissue more efficiently and safely than other systems reported to date.
Materials and Methods: An erbium:YAG laser delivery system was built to deliver laser energy in bursts of micropulses with a repetition rate of 1,000 Hz. The laser was coupled to handpieces with tip designs equipped with shields, backstops, and beveled, straight, and flexible fibers. In vivo studies in the rabbit eye were performed to determine damage threshold, optimal pulse energy, and burst frequency required to make incisions in the retina and choroid. The safety profile and directional control provided by the handpieces were tested for consistency. Partial- and full-thickness retinal-choroidal incisions were examined clinically and histologically at various time intervals.
Results: The best incisions were obtained at a fluence of 3.5 J/cm2 or greater, a burst repetition rate of 10 to 40 Hz, and 6 micropulses per burst. Retinal damage occurred when incising laser energy was used 500 microm or closer to the retinal surface. Depth of penetration of laser energy did not depend on burst repetition rate. The use of laser endoprobes equipped with shields and backstops provides absolute protection from stray laser energy in aqueous media. The use of flexible beveled fiber tips provides reliable, accurate directional control. Retinal-choroidal incisions and damage resulted in local retinal-choroidal degeneration and adhesion formation.
Conclusion: The modifications to the erbium:YAG laser scalpel provide a more efficient, versatile, and safe application to vitreoretinal surgery than any system reported to date.