Corneal incisions utilizing the 1,053-nm picosecond Nd:YLF ophthalmic laser

We evaluated the precision and predictability of a 1,053-nm picosecond Nd:YLF ophthalmic laser with various combinations of computer-controlled parameters. We utilized epithelium-free corneal-sclera preparations from NZW rabbits, and the 1,053-nm Nd:YLF laser (Intelligent Surgical Lasers, San Diego, CA, U.S.A.). X-line and line patterns were utilized to make linear corneal incisions. Three parameters (layer size, crossing width, and energy level) were evaluated. One parameter was changed for a total of 120 combinations of computer-controlled parameters. Three incisions were performed for each combination. Although the intended depths of the incisions were constant (300 mu m), the actual depths of the incisions varied with the change of parameters. Increasing layer size decreased the depth of incisions, and increasing crossing width or energy level increased the depth of incisions. Only three of 120 combinations of parameters achieved depths near 300 mu m. Within the same combination of parameters, the depth of the corneal incisions varied. 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 irregular border. Further improvements are necessary to use this laser system for corneal transverse incisions.