Comparison of Zeiss MEL90 and Alcon WaveLight EX500 Excimer Lasers in FDA Premarket Approval Trials for the Treatment of Myopia, Hyperopia, and Mixed Astigmatism

Background/Objectives: To compare visual outcomes of the U.S. Food and Drug Administration (FDA) premarket approval trials of two refractive excimer laser platforms used for the correction of myopia with and without astigmatism, hyperopia with and without astigmatism, and mixed astigmatism. Methods: Clinical outcomes were analyzed between the recently approved MEL90 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) and the WaveLight (now termed EX500) excimer laser (Alcon Laboratories, Inc., Fort Worth, TX). Results: A total of 714 eyes (358 patients) from MEL90 and 1353 eyes (706 patients) from EX500 were analyzed up to 6 months postoperatively. In the hyperopia/hyperopic astigmatism cohort, the EX500 demonstrated greater efficacy relative to MEL90, with more eyes achieving a postoperative uncorrected distance visual acuity (UDVA) of 20/20 or better (48.6% vs 68.7%, respectively; P < .001). In both the MEL90 and EX500, at least 85% of eyes with myopia/myopic astigmatism and 68% with mixed astigmatism achieved a postoperative UDVA of 20/20 or better. For all refractive cohorts, more than 95% of eyes achieved a UDVA of 20/40 or better at 6 months (all P > .05). The EX500 was more likely to demonstrate an improvement of more than 2 lines of UDVA compared to baseline CDVA (all P < .05). In contrast, the MEL90 showed greater predictability of spherical equivalent within ±0.50 D and ±1.00 D for the hyperopia/hyperopic astigmatism cohort (both P = .007), as well as within ±0.50 D for the myopia/myopic astigmatism cohort (P < .001). Postoperatively, both platforms were associated with decreased glare and halos, although findings were variable in the EX500 mixed astigmatism cohort. Conclusions: Both excimer lasers demonstrated safe and effective outcomes that exceed the threshold set by the FDA.