Corneal ablation by nanosecond, picosecond, and femtosecond lasers at 532 and 625 nm
D. Stern, R. W. Schoenlein, C. A. Puliafito, E. T. Dobi, R. Birngruber and J. G. Fujimoto
Laser Research Laboratory, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
We produced corneal excisions with nanosecond (ns)-, picosecond-, and
femtosecond (fs)-pulsed lasers at visible wavelengths. The threshold energy
for ablation was proportional to the square root of the pulse duration and
varied from 2.5 microjoules (microJ) at 100 fs to 500 microJ at 8 ns.
Excisions made with picosecond and femtosecond lasers was ultrastructurally
superior to those made with nanosecond lasers and, at pulse energies near
threshold, showed almost as little tissue damage as excisions made with
excimer lasers at 193 nm. We conclude that ultrashort-pulsed lasers at
visible and near-infrared wavelengths are a possible alternative to excimer
lasers for corneal surgery and might have advantages over conventional
ophthalmic neodymium-YAG lasers for some intraocular applications.
