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.