Date released: May 27, 1998

Keep refraction in refractive surgery planning, astigmatism expert urges

MELBOURNE, Australia - The developer of a breakthrough approach to astigmatism analysis sees a risk in the recent trend to link refractive lasers to corneal topography machines.

Eye surgeon Noel Alpins, of Melbourne, Australia, published a vector analysis approach to astigmatism in 1993. The approach was considered radical at the time for its recommendation that corneal topography - that is, the external shape of the cornea, which is the clear "window" at the front of the eye - be considered together with the patient's refraction in the surgical planning of refractive surgery. Refractive surgery is performed increasingly around the world for the correction of myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.

In 1993, almost all surgeons planned refractive surgery based entirely on a patient's refraction, a test that determines the corrective lenses a patient needs to view the standard eye chart. This surgical planning was based on recommendations from the laser manufacturers. Recently, however, some companies are linking refractive surgery lasers to corneal topography machines, which results in surgery based entirely on the cornea's shape, thus disregarding the refractive astigmatism correction.

In Alpins' view, neither approach is correct in every patient. "The pendulum has now swung too far in the other direction," he said. "It's not wise to ignore corneal shape, as we were doing before. But neither can we ignore the patient's refraction, as happens now with topography-based lasers."

Alpins' method allows the surgeon to consider both refraction and topography, and choose an optimal approach individualized for each patient. This patented methodology is included in an outcomes analysis program marketed by ASSORT Pty. Ltd., a company Alpins founded in 1991.

ASSORT is currently negotiating with makers of refractive lasers and corneal topography machines to include Alpins' method in the programming of their equipment. "Linking lasers to corneal topography machines has high-tech appeal and promises to contribute to the surgeon's control over the effects of refractive surgery," Alpins said. "But without a rational, well-defined model to bring refraction into that linkage, the efforts will fail to advance the science of refractive surgery or enhance patient care, with the risk of adverse refractive outcomes when refraction is ignored. My method provides the missing element in planning and performing this high-tech surgery by enabling the inclusion of both the refraction and topography in a measured manner."

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