Purpose: To investigate the visual and refractive outcome of wavefront-guided laser in situ keratomileusis (LASIK) to correct myopic astigmatism.
Setting: Departments of Ophthalmology of the Universities of Dresden, Dresden, Germany, and Zurich, Zurich, Switzerland.
Methods: This prospective study comprised 35 eyes of 28 patients who had a mean preoperative spherical refraction of -4.8 diopters (D) +/- 2.3 (SD) and a cylinder of -1.1 +/- 0.9 D. Preoperative and postoperative wavefront analysis was performed with a Tscherning aberrometer. A scanning-spot laser with a 1.0 mm spot size and a 200 Hz repetition rate was used. The eye-tracking system had a response time of less than 6 milliseconds. The treatment area diameter ranged from 6.0 to 7.0 mm with a transition zone of 1.0 mm.
Results: At 3 months, 68.0% of the eyes were within +/-0.5 D of emmetropia and 93.5% were within +/-1.0 D. Uncorrected visual acuity was 20/20 or better in 93.5% of eyes. No eye lost more than 1 line of low-contrast, glare, and best spectacle-corrected visual acuity (BSCVA). Supernormal vision (BSCVA of 20/10 or better) was achieved in 16.0% of eyes. The correction of higher-order aberrations (spherical aberration, coma) was insufficient, with an increase factor of the overall root-mean-square wavefront error of 1.44 +/- 0.74. Coma was better corrected than spherical aberration.
Conclusions: Wavefront-guided LASIK is a promising technique that offers the potential to correct refractive errors, to improve visual acuity, and to increase the quality of vision, especially under mesopic conditions. Studies that include selective overcorrection of different Zernike components are needed to achieve better correction of the aberrations. Prospective controlled clinical studies must clarify the major benefits of wavefront-guided LASIK.