In this report we evaluated the effect of femtosecond laser energy on the development of corneal haze and keratocyte activation in rabbits following intra-stromal photodisruption to create LASIK flaps using a modified commercial femtosecond surgical laser. Three groups of flap parameters were studied: 1.5 microJ/pulse with 10 microm spot separation and complete side cut (Group 1); 3.5 microJ/pulse with 14 microm spot separation and complete side cut (Group 2); 3.5 microJ/pulse with 14 microm spot separation and partial (50 microm) side cut (Group 3). All flaps were left attached without lifting to avoid epithelial contamination. Rabbits were then evaluated pre- and post-operatively by quantitative in vivo and ex vivo confocal microscopy. The achieved flap thickness 1 week after surgery averaged 88.9+/-12.8, 90.8+/-6.9 and 86.5+/-6.8 microm for Groups 1-3 respectively (p=NS). Interface thickness was significantly greater (p<0.05) in the higher energy groups averaging 40.0+/-11.2 and 37.7+/-5.7 microm for Groups 2-3 compared to 28.6+/-4.5 microm for Group 1. Corneal haze was barely detectible and not significantly different between groups, although haze was detected in the region of the side-cuts in Groups 1 and 2. No clinically significant changes in stromal or epithelial thickness were noted. Laser confocal microscopy showed the presence of small diameter cells within the flap interface that resided within disrupted regions of the corneal collagen lamellae. Keratocyte activation was only detected in regions of the 100% side cut and not over the flap interface. In conclusion, the results of this study indicate that photodisruption of the corneal stroma alone without flap elevation regardless of laser energy does not induce significant corneal haze in the rabbit. However, a thicker stromal interface was seen with the higher energy suggesting greater stromal damage.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2441875 | PMC |
http://dx.doi.org/10.1016/j.exer.2008.02.012 | DOI Listing |
Opt Express
August 2010
Center for Micro-integrated Optics for Advanced Bio-imaging and Control, Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA.
Temporal focusing of spatially chirped femtosecond laser pulses overcomes previous limitations for ablating high aspect ratio features with low numerical aperture (NA) beams. Simultaneous spatial and temporal focusing reduces nonlinear interactions, such as self-focusing, prior to the focal plane so that deep (approximately 1 mm) features with parallel sidewalls are ablated at high material removal rates (25 microm(3) per 80 microJ pulse) at 0.04-0.
View Article and Find Full Text PDFBackground: Spectral domain optical coherence tomography (SD-OCT) in patients can deliver retinal cross-sectional images with high resolution. This may allow the evaluation of the extent of damage to the retinal pigment epithelium (RPE) and the neurosensory retina after laser treatment. This article aims to investigate the value of SD-OCT in comparing laser lesions produced by conventional laser photocoagulation and selective retina treatment (SRT).
View Article and Find Full Text PDFJ Biomed Opt
December 2009
Medical University Hannover, Department of Otolaryngology, Carl-Neuberg-Strasse 1, Hannover, 30625, Germany.
The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices.
View Article and Find Full Text PDFOpt Lett
May 2009
Friedrich Schiller University Jena, Institute of Applied Physics, Albert-Einstein-Strasse 15,D-07745 Jena, Germany.
We report on spectral combination of four high repetition rate 5 ns pulsed Yb-doped fiber amplifiers at 1 microm wavelength. The output beam is spatially and temporally superposed by use of an all-reflective diffraction grating. 1.
View Article and Find Full Text PDFOpt Express
June 2008
Edward S. Rogers Department of Electrical and Computer Engineering and Institute for Optical Sciences, University of Toronto, 10 King's College Road, Toronto, ON M5S-3G4, Canada.
A variable (0.2 to 5 MHz) repetition rate femtosecond laser was applied to delineate the role of thermal diffusion and heat accumulation effects in forming low-loss optical waveguides in borosilicate glass across a broad range of laser exposure conditions. For the first time, a smooth transition from diffusion-only transport at 200 kHz repetition rate to strong heat accumulation effects at 0.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!