Refractive Outcomes After LASIK for the Treatment of Mixed Astigmatism with the Allegretto WaveLight EX500

INTRODUCTION: Treatment of mixed astigmatism with laser in situ keratomileusis (LASIK) is complex as the correction requires flattening the cornea in one meridian while steepening the cornea in the other meridian. The bitoric technique has become the most popular approach and has been tested across a variety of platforms. This study is the first to evaluate the results of mixed astigmatism treatment using the Allegretto WaveLight(®) EX500. METHODS: This study was a single-center, retrospective, noncomparative analysis of 400 eyes that underwent LASIK to correct for mixed astigmatism utilizing the EX500 excimer laser. Data on uncorrected distance visual acuity, corrected distance visual acuity, and spherical equivalent was analyzed at consecutive intervals (1, 3, 6, 9, and 12 months). Refractive measurements were used to perform a vector analysis. RESULTS: Three and 12 months postoperatively, 71% and 74% of eyes had an uncorrected distance visual acuity (UDVA) of 20/20 or better and 99% and 100% of eyes had a UDVA of 20/40 or better, respectively. The postoperative UDVA was within one line of the corrected distance visual acuity (CDVA) in 88% and 93% of eyes at 3 and 12 months, respectively. At 3 months, 78% of eyes achieved refractive astigmatism no greater than 0.50 diopters and at 12 months, 80% achieved this. The mean spherical equivalent refraction was − 0.36 ± 0.57 D at 12 months after surgery. At the 12-month follow-up, the mean refractive cylinder was reduced by 87%, from − 2.79 to − 0.37 diopters. On vector analysis, 99% of eyes had an angle of error within ± 15° from the intended target at 3 and 12 months. CONCLUSION: Treatment of mixed astigmatism using the Allegretto WaveLight(®) EX500 laser exceeded the industry standards of safety, efficacy, stability, and accuracy.