Laser in situ keratomileusis for high astigmatism in myopic and hyperopic eyes

To evaluate outcomes after laser in situ keratomileusis (LASIK) in highly astigmatic myopic and hyperopic eyes.

University eye clinic.

Retrospective case series.

Eyes with more than 2.0 diopters (D) of astigmatism were identified from patient records. The mean preoperative cylinder was -3.92 D ± 0.82 (SD) in myopic eyes and -4.42 ± 1.10 D in hyperopic eyes. Patients were examined preoperatively and 3 months postoperatively. Laser in situ keratomileusis was performed with a Visumax femtosecond laser and a MEL-80 excimer laser. Preoperative and postoperative refractions were converted to polar values. Induced torsion and achieved correction of sphere and cylinder were determined.

After 3 months, the mean sphere was 0.48 ± 0.68 D in myopic eyes and the mean cylinder -0.97 ± 0.52 D. Spherical equivalent (SE) correction was 0.05 ± 0.42 D from target. Astigmatism was 0.77 ± 0.62 D undercorrected (P<.01), and the mean induced torsion was -0.18 ± 0.51 D (P=.02). Astigmatic undercorrection was 21% of the intended correction. In hyperopia, the mean 3-month refraction was 0.79 ± 0.83 D in sphere and -1.38 ± 0.90 D in cylinder. The SE refraction was -0.01 ± 0.71 D from target. Astigmatism was 1.17 ± 0.81 D undercorrected (P<.01), with no significant torsion. Intended and achieved astigmatic corrections were correlated, with astigmatism being 28% undercorrected.

Laser in situ keratomileusis in highly astigmatic eyes precisely corrected SE refraction but led to astigmatic undercorrection, particularly in hyperopia. Little to no torsion of the cylinder axis was induced.