Comparing Effective Optical Zones After Myopic Ablation Between LASIK, PRK, and SMILE With Correlation to Higher Order Aberrations

PURPOSE: To explore size, decentration, and eccentricity of effective optical zones (EOZs) in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small inci- sion lenticule extraction (SMILE) and correlate them to higher order aberrations (HOAs).METHODS: This was a retrospective chart review of 188 eyes that underwent refractive surgery for compound myopia (61 LASIK, 84 PRK, 43 SMILE). EOZ measurements were deter- mined using 1-year postoperative Pentacam (Oculus Optik- gerate GmbH) tangential difference maps. HOA data were measured using Pentacam wavefront aberration Zernike poly- nomials. Correlations between EOZs and HOAs were analyzed.RESULTS: The EOZs of LASIK and PRK are smaller than SMILE at 19.54 +/- 1.44, 19.39 +/- 1.66, and 22.18 +/- 2.61 mm2, respectively (P < .001). No difference existed in absolute de- centration from corneal vertex (P = .078) or pupil center (P = .131), but horizontal and vertical components differed sig- nificantly (P < .001). Smaller EOZ areas were correlated with greater spherical aberration induction (rLASIK =-0.378, rPRK =-0.555, rSMILE =-0.501) and total HOA induction in all groups. Absolute decentration from corneal vertex posi- tively correlated with total HOA (rLASIK = 0.396, rPRK = 0.463, rSMILE = 0.399) and directional vertical coma induction nega- tively correlated with vertical decentration from the corneal vertex (rLASIK =-0.776, rPRK =-0.665, rSMILE =-0.576) in all groups.CONCLUSIONS: SMILE results in a larger EOZ than LASIK and PRK, and absolute decentration remains comparable regard- less of surgical reference center, despite horizontal/vertical differences. Surgical planning to ensure adequate EOZ size and centration may reduce induction of HOAs, including spher- ical aberrations and vertical coma.