Primary Topography-Guided LASIK: Treating Manifest Refractive Astigmatism Versus Topography-Measured Anterior Corneal Astigmatism

PURPOSE: To investigate whether topography-guided laser in situ keratomileusis (LASIK) with anterior corneal astigmatism measured on the WaveLight Contoura (Alcon Laboratories, Inc., Fort Worth, TX) leads to better refractive outcomes compared to treating on the clinically measured manifest refractive astigmatism axis in eyes with primary myopic astigmatism. METHODS: Retrospective analysis of 1,274 consecutive LASIK eyes treated on the topography-measured anterior corneal astigmatism axis compared to eyes treated on the conventional clinical manifest refractive astigmatism axis. RESULTS: In eyes with a small axis discrepancy between anterior corneal astigmatism and refractive astigmatism of 5 degrees to 20 degrees, there was no significant difference in efficacy index, refractive astigmatism accuracy, and most Alpins vector analysis parameters. Both treatment modalities achieved 20/20 uncorrected distance visual acuity (UDVA) in 90% of eyes, with 95% having postoperative cylinder of 0.50 diopters (D) or less. In eyes with a large axis discrepancy between 21 degrees and 45 degrees treated on the anterior corneal astigmatism axis, outcomes were both statistically and clinically inferior. Fewer eyes achieved UDVA of 20/20 (88.9% vs 73.6%; P = .01) and fewer had a defocus equivalent of 0.25 (65.6% vs 52.7%), 0.50 (86.9% vs 80.0%), and 0.75 (97.5% vs 90.9%) D or less (P < .05 for all). Significantly more eyes achieved an angle of error greater than 15 degrees (25.4% vs 8.1%; P = .004), had postoperative residual astigmatism of 0.75 D or less (18.2% vs 7.4%; P = .03), and needed an excimer laser re-treatment (11% vs 1.6%; P = .007). CONCLUSIONS: Topography-guided myopic astigmatism LASIK treated on the topography-measured anterior corneal astigmatism axis resulted in inferior refractive and visual outcomes compared to treating on the clinical manifest refractive astigmatism axis.