[Intrastomal refractive surgery with ultra-short laser pulses. Results from initial in vitro experiments].
OBJECTIVE
To investigate the possibilities and techniques for intrastromal ablation of the cornea by the use of ultra-short laser pulses.


METHODS
A laser-induced plasma with a diameter of 8 mu was generated 100-300 mu below Bowmans membrane by focussing of a Ti:Saphir laser (lambda=805 nm, pulse width: 115 fs, energy: 0.6-3.3 microJ). Scanning the laser beam enabled arbitrary transsections in the corneal stroma. All experiments were performed in porcine eyes 1-4 h post-mortem.


RESULTS
Two-dimensional sections were achieved applying a minimal laser energy of 0.6 microJ at a separation of the single laser effects of 10 micrometer. A 150 micrometer thick disc was excised 150 micrometer below Bowmans membrane and extracted through a keratotomy performed by the laser. Sharp-cut edges were observed by slit-lamp biomicroscopy.


CONCLUSIONS
Ultra-short laser pulses are suitable for precise intrastromal ablation.
Hammer
M
M
Augenklinik der FSU Jena, Germany. martin.hammer@med.uni-jena.de
Schweitzer
D
D
Ziegler
W
W
Wiechmann
M
M
Strobel
J
J
D000818:Animals; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008853:Microscopy; D009887:Ophthalmoscopy; D012029:Refraction, Ocular