Ablation centration compared

August 15, 2011

When performing LASIK in eyes with hyperopia with a large positive angle kappa, centering the ablation on the corneal vertex rather than the pupil centroid provides superior results.

San Diego-When performing LASIK in eyes with hyperopia with a large positive angle kappa, centering the ablation on the corneal vertex rather than the pupil centroid provides superior results, said Ahmed M. Khalifa, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

All flaps were created with a single microkeratome (M2, Moria) and the treatments were performed using the same laser (Amaris, Schwind) with an aspheric (aberration-free) ablation profile and a 6-mm ablation zone and 9-mm blend zone. The offset option of the laser was used for the ablations centered over the corneal vertex.

"Large positive angle kappa is common in hyperopic eyes, and our findings indicate that in these cases, centration over the corneal vertex results in better safety and visual function than centration over the pupil centroid," Dr. Khalifa said. "However, additional studies including larger numbers of patients and a longer duration of follow-up are needed to corroborate our findings."

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