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

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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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