Clinical Ophthalmology (Feb 2024)
Correlational Analysis of the Effective Optical Zone with Myopia, Myopic Astigmatism, and Spherical Equivalent in LASIK, PRK, and SMILE
Abstract
Majid Moshirfar,1– 3 Michael S Herron,4 David S Cha,5 Jordan M Santos,6 Levi T Miller,7 Phillip C Hoopes Sr1 1Hoopes Vision Research Center, Hoopes Vision, Draper, UT, 84020, USA; 2John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA; 3Utah Lions Eye Bank, Murray, UT, USA; 4University of Nevada, Reno School of Medicine, Reno, NV, USA; 5Saint Louis University School of Medicine, St. Louis, MO, USA; 6University of Arizona, Phoenix School of Medicine, Phoenix, AZ, USA; 7Utah State University, Department of Electrical and Computer Engineering, Logan, UT, USACorrespondence: Majid Moshirfar, Hoopes Vision Research Center, 11820 S. State St. #200, Draper, UT, 84020, USA, Tel\Fax +1 801-568-0200, Email [email protected]: We assess the relationship between preoperative myopic sphere, astigmatism, and spherical equivalent and effective optical zone (EOZ) size, shape, and decentration within individual populations of post-LASIK, PRK, and SMILE patients.Patients and Methods: A retrospective chart review was conducted with 118 LASIK, 144 PRK, and 41 SMILE eyes from 179 total patients that underwent compound myopic ablation. One-year postoperative Pentacam tangential difference maps were used for EOZ data measurements. Correlational analysis between compound myopic measures [sphere, cylinder, manifest refractive spherical equivalent (MRSE)] and EOZ parameters was performed, and differences between groups of myopic sphere and cylinder within each surgery type were assessed.Results: An increase in absolute myopic sphere (and subsequent MRSE) is associated with a smaller EOZ area in SMILE (r=0.454, p=0.003) and a more circular EOZ shape in LASIK (r=0.396, p< 0.001) and PRK (r=0.563, p< 0.001). An increase in absolute myopic cylinder is associated with an increased EOZ area in all three surgery types [LASIK (r=− 0.459, p< 0.001), PRK (r=− 0.716, p< 0.001), SMILE (r=− 0.429, p=0.005)] and a more elliptical EOZ in LASIK (r=− 0.491, p< 0.001) and PRK (r=− 0.538, p< 0.001).Conclusion: While astigmatism may be correlated to EOZ size within all three refractive surgery types, myopic sphere alone is insufficient to estimate EOZ size differences for procedures with a large blend zone of ablation like LASIK or PRK. Shape is just as important a factor as size to consider when examining corneal EOZ differences; reported correlative findings likely result from inherent differences in surgical technique and abruptness of planned surgical ablation borders.Keywords: EOZ, OZ, Pentacam, tangential difference map
