Vector Analysis Outcomes after Femtosecond Laser In-Situ Keratomileusis (FS-LASIK) Versus Small Incision Lenticule Extraction (SMILE) for Moderate Myopic Astigmatism
John Arvin B. delos Reyes, MD, Kathrina Therese O. Mendoza, MD, Reginald Robert G. Tan, MD
Tan Eng Gee Eye Institute, St. Luke’s Medical Center – Global City, Taguig, Philippines
Correspondence: John Arvin B. delos Reyes, MD
Clinic Address: Borough LASIK Center, 2F North Parking Building, SM Mall of Asia Wellness Zone, Pasay City, Philippines
Clinic Phone Number: +639177072306
E-mail Address: jarvindlr@gmail.com
Disclosure: The authors report no conflict of interest.
ABSTRACT
Objectives: To compare the vector analysis, visual, and refractive outcomes of femtosecond-assisted laser in-situ keratomileusis (LASIK) and small incision lenticule extraction (SMILE) among myopic patients with moderate myopic astigmatism.
Methods: This was a single-center, retrospective, cohort study that compared eyes that underwent femtosecond LASIK or SMILE for the correction of myopia and astigmatism of 0.75 to 3.0 diopters. Vector analysis and standard graphs for reporting visual and refractive outcomes were utilized for analysis.
Results: There were 82 femtosecond LASIK-treated eyes and 80 SMILE-treated eyes with similar preoperative characteristics except for slightly higher mean preoperative sphere refraction in the SMILE group (-4.2±2.4 D vs -4.9±1.6 D, p=0.03). At 3 months, femtosecond LASIK group had better mean uncorrected distance visual acuity (UDVA) (LogMAR 0.006±0.06 vs 0.06±0.09, p=0.00) and had more eyes achieving postoperative UDVA of 20/20 or better (88% versus 56%). Although there were similar postoperative spherical equivalents, residual astigmatism was higher in the SMILE group (0.11±0.22 D vs 0.32±0.30 D, p=0.00). Vector analyses showed significantly better outcomes for femtosecond LASIK than for SMILE in terms of difference vector (DV), index of success (IOS), torque, and flattening index (FI). A trend for undercorrection for higher astigmatism was seen in both groups that was greater in the SMILE group. Both groups showed high safety with the majority of eyes showing postoperative corrected distance VA (CDVA) within 1 line of preoperative CDVA (98.8% versus 91.2%).
Conclusion: Although femtosecond LASIK and SMILE have similar predictability at 3 months, femtosecond LASIK has relatively better efficacy and superior astigmatic outcomes than SMILE for the correction of moderate myopic astigmatism.
Keywords: Femtosecond LASIK, SMILE, vector analysis, myopic astigmatism, low to moderate astigmatism