Excimer laser photorefractive keratectomy to correct astigmatism

PURPOSE: To evaluate the efficacy of excimer laser photorefractive keratectomy (PRK) to correct astigmatism. SETTING: Hôpital Morvan, Brest, France. METHODS: A 193 nm excimer laser was used to perform toric ablation with an expanding slit to flatten the cornea in the steeper meridian and/or to correct myopia with an iris diaphragm in 72 eyes (55 patients): 68 eyes for compound myopic astigmatism and 4 for astigmatism only. RESULTS: Preoperative cylinder was -2.14 diopters (D) +/- 1.99 (SD) (range -0.50 to -5.50 D); 6 months postoperatively, it was -1.75 +/- 1.34 D (range -0.25 to -5.25 D). Preoperative spherical equivalent was -5.33 +/- 3.22 D (range -0.25 to -14.50 D); 6 months postoperatively, it was -0.86 +/- 2.32 D (range 2.50 to -9.75 D). The axial error was within 30 degrees. Uncorrected visual acuity was 0.50 or better in 64.5% of patients. CONCLUSIONS: Overall patient satisfaction seemed the result of the myopic correction; cylindrical correction was incomplete. Future software refinements should improve the results. In particular, single elliptical ablation seems to offer theoretical advantages.