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The Ideal Excimer Beam for Refractive Surgery
PURPOSE
To identify essential considerations for the optimal excimer laser beam for refractive laser surgery and further to determine specific beam parameters fulfilling the essential requirements.
METHODS
Starting with the fundamental laser tissue interaction, the various parameters defining the laser beam are analyzed and optimal values for each are evaluated.
RESULTS
Gaussian beams generally produce smoother ablated surfaces than “flat top” beams. Optimal ablation efficiency for a Gaussian profile occurs at a peak laser fluence of approximately 450 mJ/cm2. To treat realistic optical aberrations the Gaussian spot size should be <0.9 mm. The laser repetition rate for such a beam can be multiple hundred hertz without causing thermal damage if a “flying spot” strategy is used. Accurate treatment under such conditions requires both high-fidelity laser spot placement and high-performance eye tracking.
CONCLUSIONS
Surgical systems using the characteristics defined in this study should yield excellent treatment outcomes. [J Refract Surg. 2006;22:S969-S972.]
AUTHOR
From Alcon Orlando Technology Center, Orlando, Fla.
Dr Pettit is Chief Scientist at Alcon Orlando Technology Center, Orlando, Fla.
Correspondence: George H. Pettit, MD, PhD, 2501 Discovery Dr, Ste 500, Orlando, FL 32826. Tel: 407.384.1628; E-mail: george.pettit@alconlabs.com