Aspheric ablation profile offers safe, effective correction of myopia with astigmatism

J Refract Surg. 2010;26(2):88-98.

A new excimer laser that offers a non-wavefront-guided aspheric ablation profile for LASIK proved safe and effective in correcting low to moderate myopic astigmatism, according to a study.

"Compared to other studies using non-wavefront-guided profiles, we found less amounts of induced higher-order aberrations in our sample," the study authors said.

The prospective, multicenter study included 358 eyes of 179 patients who underwent bilateral LASIK for myopia and astigmatism. Mean patient age was 28 years. Mean preoperative manifest refraction spherical equivalent was –3.47 D, mean sphere was –3.13 D and mean cylinder was –0.69 D.

Investigators assessed uncorrected visual acuity, best corrected visual acuity, manifest refraction spherical equivalent, contrast sensitivity, corneal topography, corneal wavefront, ultrasound corneal pachymetry, pupillometry, slit lamp examination and dilated fundus images before surgery. The same measurements, except dilated fundus imaging, pupillometry and contrast sensitivity, were also performed at 1 week, 1 month, 3 months and 6 months after surgery.

LASIK was performed with an Amaris flying-spot excimer laser (Schwind) programmed with a non-wavefront-guided aspheric ablation algorithm. The Carriazo-Pendular microkeratome (Schwind) was used to create flaps with a superior hinge, and the Amadeus microkeratome (Ziemer) was used to create flaps with a nasal hinge. An infrared eye tracker centered on the pupil was used to attain proper alignment.

At 6 months after surgery, mean manifest refraction spherical equivalent was –0.21 D, mean sphere was –0.12 D and mean postop cylinder was –0.17 D. Ninety-six percent of eyes had manifest refraction spherical equivalent within 0.5 D. UCVA was 20/20 or better in 98% of eyes; no eyes lost two or more lines of BCVA. Contrast sensitivity was unchanged at 6 months, the authors said.