Full Content is available to subscribers

Subscribe/Learn More  >
Proceedings Article

Corneal ablation using the pulse stretched free electron laser

[+] Author Affiliations
Mark A. Mackanos, Karen M. Joos, John A. Kozub, E. D. Jansen

Vanderbilt Univ. (USA)

Proc. SPIE 5688, Ophthalmic Technologies XV, 177 (May 02, 2005); doi:10.1117/12.596603
Text Size: A A A
From Conference Volume 5688

  • Ophthalmic Technologies XV
  • Fabrice Manns; Per G. Soederberg; Arthur Ho; Bruce E. Stuck; Michael Belkin
  • San Jose, CA | January 22, 2005

abstract

The Mark-III Free Electron Laser (FEL), tuned to λ=6.45 μm has been demonstrated to provide for efficient ablation in ocular and neural tissues with minimal collateral damage. To date, the role of the FEL pulse structure on the mechanism of ablation has not been determined. In an effort to study the role of the FEL micropulse on the ablation of corneal tissue, the native pulse structure of the FEL, a 2.85 gigahertz repetition of picosecond pulses within a five microsecond macropulse envelope, was changed using a a pulse stretcher. This device changes the duration of the micropulse from 1 picosecond to 30-200 picoseconds in length, thus reducing the peak intensity of the micropulse by as much as 200x the original intensity, while the macropulse energy remains unchanged. Two basic metrics were studied: the ablation threshold on water and the ablation crater depth on gelatin. These metrics were employed at λ=6.45 and 6.1 μm for 1, 100, and 200 picoseconds in micropulse duration. The results showed a very slight difference between the 1, 100, and 200 picosecond micropulse duration, given a 200 fold decrease in peak energy for both the threshold and crater depth measurements. Brightfield imaging was also performed to probe the ablation dynamics and showed no difference between the 1 and 200 ps micropulses. The effect of changing the micropulse duration was studied on the ablation of canine cornea. Craters (500 micron diameter) were created with 25 pulses at three times the ablation threshold as determined for water on freshly enucleated corneas within 12 hours of removal. Three rows of seven craters were created on the center of each cornea. The native one picosecond micropulse and 200 picosecond stretched micropulse were compared at λ=6.1 and 6.45 μm. Histological data shows that less thermal damage is present at 6.1 μm compared with 6.45 μm; however, there is no significant difference between the native and stretched pulses with respect to thermal damage.

© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Citation

Mark A. Mackanos ; Karen M. Joos ; John A. Kozub and E. D. Jansen
"Corneal ablation using the pulse stretched free electron laser", Proc. SPIE 5688, Ophthalmic Technologies XV, 177 (May 02, 2005); doi:10.1117/12.596603; http://dx.doi.org/10.1117/12.596603


Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).

Figures

Tables

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Book Chapters

Topic Collections

Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.