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LaserSight laser approved for myopic, astigmatic LASIK
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WINTER PARK, Fla. — The LaserScan LSX excimer laser system has received U.S. regulatory approval for use in myopic astigmatic LASIK. The scanning spot laser was approved for treating refractive errors of up to –6 D spherical equivalent, with or without astigmatism of up to 4.5 D, using LASIK.
LaserSight Inc. received Food and Drug Administration (FDA) approval in Nov. 1999 to market the LaserScan LSX for treatment of myopia up to 6 D with photorefractive keratectomy.
According to a release from LaserSight, the system’s software plans corneal ablations by subtracting the desired final corrected corneal surface from the initial uncorrected corneal surface. Blending in the transition zone -- the area between the edge of the optical zone and the edge of the treatment zone -- ensures that the optical zone maintains the ideal corneal profile and minimizes the transition between corrected and uncorrected corneal tissue. In planning ablations for the correction of astigmatism, the minor axis of the astigmatic correction is always equal to or greater than the diameter of the optical zone, the LaserSight statement said. This provides a true circular optical zone that can encompass the circular pupil, the statement said.
The LSX software plans astigmatic corrections using a cross-cylinder algorithm, according to the LaserSight statement. The cross-cylinder approach to ablation planning minimizes the amount of tissue removed for an intended correction. LaserSight has used this cross-cylinder approach in all non-U.S. versions of its LSX software. The transition zone blends the curved corneal surface to provide a smooth interface between corrected and uncorrected corneal tissue, the statement said.