Biomechanical study of cornea response under orthokeratology lens therapy: A finite element analysis

Abstract

Orthokeratology (OK) is becoming a mainstream modality for myopia correction and control, but its underlying mechanism is not yet fully understood. In this study, the biomechanical response of cornea under the OK lens was investigated to further understand the mechanism of OK therapy. Numerical models of the cornea and OK lens with different corneal refractive powers and myopia degrees were established to analyze features and differences of the spatial displacement and stress distribution in different areas of the anterior corneal surface by finite element method. Displacement distributions on the anterior cornea surface with refractive powers of 39.5, 43, 46 D, and myopia degrees of −1.0, −3.0, −6.0 D demonstrate similar deformation trends and nearly rotationally symmetrical attributes of different corneal parameters. Displacement of mid‐peripheral cornea was significantly high compared with that of the central and peripheral cornea, peaking at ~2.4 mm off the corneal apex. The stress increased with the increase in myopia degrees and was significantly large for the myopia degrees of −6.0 D at S1; the stress at S2 and S6 was low and stable and did not differ much at S3; the stress at S4 and S5, however, was extremely high. In summary, simulation result of orthokeratology can effectively evaluate the performance of OK lens and it properly associates with the differential map of the corneal topography. The base curve of the OK lens may also play a role in mid‐peripheral corneal steepening. The design around the OK lens' alignment curve needs to be optimized.

FEA-Based Stress–Strain Barometers as Forecasters for Corneal Refractive Power Change in Orthokeratology

“…However, it was not clinically validated [13] and Zhao et al conducted a more detailed simulation-based FEA where stresses and displacements were investigated. The study confirmed the association between the displacement and differential power maps but without full clinical validation [16]. Both studies disregarded Ortho-K lens decentration entirely, substantially limiting their study results.…”

“…Clinically, the eyelid is the most difficult to quantify in terms of position, blink rate and the force it applies to the lens and eye. This study applied a novel eyelid boundary edge detection that enabled the FEA model to mimic the effect of the eyelid pressure on both the lens and eye rather than only applying the pressure normally on the contact lens front surface as in previous work [14][15][16]. The previous method of eyelid representation was a limitation, as the eyelid pressure direction followed the contact lens's front surface geometry normally rather than the eyelid's back surface geometry.…”

Recent advances in computational methods for cardiovascular and musculoskeletal biomechanics and biomedicine

“…The papers in the special issue address a wide range of problems spanning the diagnosis or treatment of vascular diseases, optimization of artificial heart valves, and evaluation of orthokeratology lens therapy. Among the eight papers focused on biomechanical problems, two papers are devoted to improving the modeling methods for predicting coronary fractional flow reserve based on medical images 1,2 ; two papers investigate the influences of vascular anatomy, operative method, or device selection on the risk of complications following interventional treatments of aortic arch aneurysms or abdominal aortic aneurysms 3,4 ; two papers address hemodynamic changes induced by the interventional treatment or drug therapy of venous diseases 5,6 ; one paper is dedicated to optimizing the fatigue performance of polymeric heart valve 7 ; and one paper explores the biomechanical responses of cornea to orthokeratology lens therapy 8 . In addition, there is one paper dealing with medical image processing where a new algorithm is proposed to segment pelvic bone tumors based on multimodal images 9…”