LAUSR

PURPOSE To evaluate the postoperative behavior of the central corneal stroma thickness after myopic femto-LASIK and SMILE by using a combined anterior segment-OCT and placido disc topographer, and to compare the accuracy of both laser machines in predicting the real stromal change . SETTING Vissum Miranza, Alicante, Spain. STUDY DESIGN Prospective, observational, comparative study. METHODS The Visumax-500kHz femtosecond laser (FS), and the Amaris-750 excimer laser were used for the correction of myopia with or without myopic astigmatism. Central and paracentral stromal thicknesses (ST) and 6mm-corneal aberrometry were obtained with the MS39 topographer. Laser predicted stromal consumption was recorded (maximum lenticule thickness for SMILE and central ablation depth for LASIK). Visual and refractive outcomes were also evaluated. Total follow-up was 6 months. RESULTS 77 LASIK-eyes were matched with 77 SMILE-eyes. Mean preoperative spherical equivalent (SE) was -3.92±1.67D for LASIK and -4.02±1.63D for SMILE;p=0.356. After LASIK, ST parameters showed a significant rethickening between months 1-3 (+4.38µm for central-ST;p<0.001), remaining stable thereafter. After SMILE, all ST parameters remained stable from month-1. Stromal ablation prediction was higher for SMILE compared to LASIK for all SE ranges, although postoperatively such differences were significant only for ametropias≤4D. At 6 months, mean SMILE laser prediction error was -13.21±7.00µm, while LASIK prediction showed better accuracy (+0.92± 8.16µm; p<0.001). CONCLUSIONS The accuracy of the Amaris-750 excimer laser in predicting the stromal consumption after LASIK was better than the VisuMax-FS laser for SMILE. While SMILE stromal thicknesses remained stable from month-1, after LASIK a mild stromal rethickening was observed up to the third month.