Wave front aberrations induced from biomechanical effects after customized myopic laser refractive surgery in finite element model.

Ruirui Du,Shifeng Nie,Huirong Xiao,Lihua Fang,Jiahui Gong,Ruizhi Yang,Yu Dai,Jiahao Deng,Weijian Peng

doi:10.1007/s10792-021-02003-9

Ruirui Du, Shifeng Nie + Show 7 more

Open Access

https://doi.org/10.1007/s10792-021-02003-9

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Journal: International ophthalmology	Publication Date: Aug 15, 2021
Citations: 1	License type: cc-by

Affiliation: Nanchang Hangkong University

Abstract

A customized myopic refractive surgery was simulated by establishing a finite element model of the human eye, after which we studied the wave front aberrations induced by biomechanical effects and ablation profile after wave front-guided LASIK surgery. Thirty myopia patients (i.e., 60 eyes) without other eye diseases were selected. Their ages, preoperative spherical equivalent, astigmatism, and wave front aberration were then obtained, in addition to the mean spherical equivalent error range - 4 to - 8D. Afterward, wave front-guided customized LASIK surgery was simulated by establishing a finite element eye model, followed by the analysis of the wave front aberrations induced by the surface displacement from corneal biomechanical effects, as well as customized ablation profile. Finally, the preoperative and induced aberrations were statistically analyzed. Comatic aberrations were the main wave front abnormality induced by biomechanical effects, and the wave front aberrations induced by the ablation profile mainly included coma and secondary coma, as well as sphere and secondary-sphere aberrations. Overall, the total high-order aberrations (tHOAs), total coma (C31), and sphere ([Formula: see text]) increased after wave front-guided customized LASIK surgery. According to our correlation analyses, coma, sphere, and tHOAs were significantly correlated with decentration. Additionally, the material parameters of ocular tissue were found to affect the postoperative wave front aberrations. When the material parameters of the sclera remained constant but those of cornea increased, the induced wave front aberrations were reduced. All biomechanical effects of cornea and ablation profile had significant effects on postoperative wave front aberrations after customized LASIK refractive surgery; however, the effects of the ablation profile were more notorious. Additionally, the characteristics of biomechanical materials have influence on the clinical correction effect.

Highlights

The are many forms of laser refractive surgery and LASIK( laser-assisted in situ keratomileusis) is one of the them
Cornea and sclera were divided into different-sized hexahedral meshes based on their shape and characteristics using finite element analysis and the Ansys software, Because our study focused on the cornea, the cornea meshing was relatively smaller than that of the sclera
We studied the wavefront aberrations induced by the ablation profile of customized refractive surgery

Summary

Introduction

The are many forms of laser refractive surgery and LASIK( laser-assisted in situ keratomileusis) is one of the them. LASIK is the most commonly performed laser refractive surgery due to its short recovery times and superior safety and efficacy[1]. Vision correction through this procedure is achieved by changing the curvature of the cornea. In a conventional LASIK procedure, a hinged flap is first created using a microkeratome. Alió et al[3] found that LASIK for myopia over -10 D is a safe procedure with myopic regression that slows down with time and a high rate of best spectacle-corrected visual acuity increase in the long-term. Many clinical studies have shown that LASIK surgery increases the likelihood of corneal higher-order aberrations[6, 7]

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