The ideal excimer beam for refractive surgery.
OBJECTIVE
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.
Pettit
George H
GH
Alcon Orlando Technology Center, Orlando, FL, USA. george.pettit@alconlabs.com
D003315:Cornea / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000295:instrumentation*; D006801:Humans; D054140:Refractive Surgical Procedures; D013817:Thermography