Photodisruption in the human cornea as a function of laser pulse width.
J Refract Surg
; 13(7): 653-8, 1997.
Article
em En
| MEDLINE
| ID: mdl-9427203
ABSTRACT
BACKGROUND:
We investigated the role of laser pulse width in determining fluence thresholds and efficiency for corneal photodisruption.METHODS:
A laser system that delivers a wide range of pulse energies and pulse widths was used to produce ablations at pulse widths from 100 femtoseconds (fs) to 7 nanoseconds (ns). The laser-induced breakdown fluence threshold at each pulse width was determined by monitoring individual plasma emissions. Using multiple shots, the photodisruption threshold and cutting depth at each pulse width were determined histologically.RESULTS:
Corneal breakdown thresholds decreased at a faster rate from 7 ns to approximately 10 picoseconds (ps), compared to further reductions in pulse width below 10 ps, where little variation was seen. Breakdown for pulse widths below 10 ps showed little intershot variability, resulting in highly reproducible fluence thresholds. Corneal tissue examined histologically showed similar fluence dependency.CONCLUSIONS:
Corneal tissue photodisruption thresholds demonstrate pulse width dependence. At pulse widths less than 10 ps and with fluences near the breakdown threshold, ablations are maximally precise and efficient. These findings suggest optimal laser parameters for corneal surgery.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Córnea
/
Terapia a Laser
Limite:
Humans
Idioma:
En
Revista:
J Refract Surg
Assunto da revista:
OFTALMOLOGIA
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Estados Unidos