CORNEAL INCISIONS UTILIZING THE 1,053-NM PICOSECOND ND-YLF OPHTHALMICLASER

We evaluated the precision and predictability of a 1,053-nm picosecond Nd:YLF ophthalmic laser with various combinations of computer-control led parameters. We utilized epithelium-free corneal-sclera preparation s from NZW rabbits, and the 1,053-nm Nd:YLF laser (Intelligent Surgica l Lasers, San Diego, CA, U.S.A.). X-line and line patterns were utiliz ed to make linear corneal incisions. Three parameters (layer size, cro ssing width, and energy level) were evaluated. One parameter was chang ed for a total of 120 combinations of computer-controlled parameters, Three incisions were performed for each combination. Although the inte nded depths of the incisions were constant (300 mu m), the actual dept hs of the incisions varied with the change of parameters. Increasing l ayer size decreased the depth of incisions, and increasing crossing wi dth or energy level increased the depth of incisions. Only three of 12 0 combinations of parameters achieved depths near 300 mu m. Within the same combination of parameters, the depth of the corneal incisions va ried. Debris of ablated stromal tissue was observed at the border and partially occupying the incision. Most of the incisions were ''funnel' '-shaped with the distal treatment zone having a ''zigzag'' or irregul ar border. Further improvements are necessary to use this laser system for corneal transverse incisions.