Corneal Asphericity and Higher-Order Aberrations after FS-LASIK and Trans-PRK for Myopia.

Yuan Wu,Guiqin Wang,Shuhan Wang,Yue Huang,Ruihua Wei,Shaozhen Zhao,David P Piñero

doi:10.1155/2021/3765046

Abstract

Objective To compare the corneal asphericity and higher-order aberrations (HOAs) of femtosecond laser-assisted in situ keratomileusis (FS-LASIK) with Smart Pulse Technology (SPT) assisted transepithelial photorefractive keratectomy (Trans-PRK) for myopia and myopic astigmatism correction. Methods This prospective study analyzed 88 eyes of 44 patients treated with FS-LASIK and 64 eyes of 32 patients treated with Trans-PRK. All eyes had low to moderate myopia with or without astigmatism (spherical equivalent (SE) <−6.00 diopters). The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), SE, asphericity (Q value) of the anterior corneal surface, index of surface variance (ISV), corneal higher-order aberrations (HOAs), vertical coma (Z3−1), horizontal coma (Z31), and spherical aberration (Z40) over a 6 mm diameter central corneal zone diameter were evaluated preoperatively and 1, 3, and 6 months postoperatively. Results At 6 months, the UDVA and SE were −0.14 ± 0.06 and 0.33 ± 0.33D in FS-LASIK and −0.15 ± 0.06 and 0.35 ± 0.37D in Trans-PRK. There was no difference between the two groups in the postoperative UDVA and SE (P > 0.05). After FS-LASIK and Trans-PRK, the Q values in the 6, 7, 8, and 9 mm zones and ISV of the anterior corneal surface significantly increased (P < 0.001). At 1, 3, and 6 months after surgery, corneal HOA, Z3−1, Z31, and Z40 in both groups were significantly increased compared with those before surgery, with statistically significant differences (P < 0.001). At 1, 3, and 6 months after surgery, the Z3−1 of the Trans-PRK group was significantly lower than that of the FS-LASIK group (P < 0.001). ΔHOA and ΔZ40 were dramatically correlated with the ΔQ value for both FS-LASIK and Trans-PRK procedures. The ΔQ was significantly correlated with the preoperative SE, AD, and AD/CCT after both two procedures (all P < 0.001). Conclusions Both FS-LASIK and Trans-PRK caused the anterior corneal surface to become flatter, and the morphology of the corneal surface was irregular. Corneal HOAs were significantly increased after the two procedures. Trans-PRK using SPT introduced less corneal vertical coma than FS-LASIK. Corneal asphericity changes contributed to the corneal aberrations changes following FS-LASIK and Trans-PRK.

Highlights

Corneal refractive surgery has developed rapidly, and its safety, efficacy, and predictability have been continuously improved with the development of science and technology
ΔHOA and ΔZ40 were dramatically correlated with the ΔQ value for both FS-LASIK and Trans-PRK procedures. e ΔQ was significantly correlated with the preoperative spherical equivalent (SE), ablation depth (AD), and AD/CCT after both two procedures
FS-LASIK: femtosecond laser-assisted in situ keratomileusis; Trans-PRK: transepithelial photorefractive keratectomy; CDVA: corrected distance visual acuity; UDVA: uncorrected distance visual acuity; SE: spherical equivalent; D: diopters, CCT: central corneal thickness; K1: cornea flat meridian curvature; K2: cornea steep meridian curvature

Summary

Introduction

Corneal refractive surgery has developed rapidly, and its safety, efficacy, and predictability have been continuously improved with the development of science and technology. Has become a highly researched topic in recent years. It is characterized by one-step removal of the corneal epithelium and correction of refractive errors, which shortens the operation time and avoids the complications caused by FSLASIK to make the corneal flap [1]. With this breakthrough, Smart Pulse Technology (SPT) has been applied to excimer laser to smooth the corneal surfaces, resulting in faster postoperative recovery from Trans-PRK [2].

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