Differences in the Corneal Biomechanical Responses to LASIK and KLEx Based on Parametric Numerical Simulation.

Purpose: To use parametric numerical simulation to characterize and compare the differences in corneal biomechanical responses to laser in situ keratomileusis (LASIK) and keratorefractive lenticule extraction (KLEx) under various surgical settings.

Methods: The Finite Element Model was used in a parametric study to evaluate corneal biomechanical responses to LASIK and KLEx, considering variations in preoperative corneal thickness, corneal flap/cap thickness and diameter, refractive correction, and optical zone diameter. Surgery-induced stress, displacement, and interface contact pressure were compared between LASIK and KLEx using the Wilcoxon signed-rank test.

Evaluating corneal cross-linking using Stress-Strain Index maps: a finite element study.

Keratoconus (KC) is a progressive corneal ectasia leading to visual impairment if untreated. Corneal collagen cross-linking (CXL) is an effective treatment to halt KC progression by strengthening corneal biomechanics. However, current CXL treatments lack customization based on regional corneal stiffness, which is crucial for optimal outcomes.

Ye's Swing Technique for Small-incision Lenticule Extraction Surgery.

We propose a novel approach for small incision lenticule extraction (SMILE) surgery, termed the Ye's Swing Technique. The separation and removal of the lenticule are among the most challenging steps of SMILE surgery. An improper technique can result in difficulties during lenticule extraction, lenticule rupture, and the presence of residual fragments.

Diurnal variations in corneal biomechanics in healthy young adults.

Purpose: To assess the diurnal changes in corneal biomechanics in healthy young adults.

Methods: At Wenzhou Medical University Eye Hospital in China, a prospective case series. Each healthy subject had six Corvis ST examinations, from 10:00 on a first day to 6:00 on the following day, at 4-hour intervals.

Crystalline lens power and astigmatism calculation in myopia by swept-source optical coherence tomography: A pilot study.

Purpose: To calculate the crystalline lens power and astigmatism, as well as their changes following cycloplegia, in individuals with myopia using swept-source optical coherence tomography (SS-OCT).

Methods: Participants were divided into two groups according to axial length (AL). Crystalline lens parameters, including power, lens thickness (LT), anterior chamber depth (ACD), and astigmatism, were measured with SS-OCT and analysed before and after cycloplegia.

Corneal higher-order aberrations and their relationship with choroid in myopic patients.

Background: To investigate corneal higher-order aberrations (HOAs) and choroidal characteristics in myopic individuals and explore the association between HOAs and choroidal parameters.

Methods: Myopic participants were categorized into three groups based on axial lengths (ALs). We compared corneal HOAs, including spherical (Z), comatic (Z  and Z), and trefoil (Z  and Z) aberrations, as well as choroidal vascularity index (CVI) and choroidal thickness (CT).

In Vivo Corneal Biomechanical Response to Three Different Laser Corneal Refractive Surgeries.

Purpose: To compare the effects of three common refractive surgeries on corneal biomechanics.

Methods: Two hundred seven patients who had refractive surgery were included in this study, of whom 65 received transepithelial photorefractive keratectomy (tPRK), 73 received femtosecond laser-assisted laser in situ keratomileusis (FSLASIK), and 69 received small incision lenticule extraction (SMILE). Each patient had biomechanical measurements using the Corvis ST (Oculus Optikgeräte GmbH) preoperatively and at 3 and 6 months postoperatively.

Effect of corneal cross-linking on biomechanical changes following transepithelial photorefractive keratectomy and femtosecond laser-assisted LASIK.

To evaluate the change in corneal biomechanics in patients with postoperative ectasia risk when combining two common laser vision correction procedures (tPRK and FS-LASIK) with cross-linking (in tPRK Xtra and FS-LASIK Xtra). The study included 143 eyes of 143 myopic, astigmatic patients that were divided into non-cross-linked refractive surgery groups (non-Xtra groups, tPRK and FS-LASIK) and cross-linked groups (Xtra groups, tPRK Xtra and FS-LASIK Xtra) according to an ectasia risk scoring system. The eyes were subjected to measurements including the stress-strain index (SSI), the stiffness parameter at first applanation (SP-A1), the integrated inverse radius (IIR), the deformation amplitude at apex (DA), and the ratio of deformation amplitude between apex and 2 mm from apex (DARatio2mm).

CorNet: Autonomous feature learning in raw Corvis ST data for keratoconus diagnosis via residual CNN approach.

Purpose: To ascertain whether the integration of raw Corvis ST data with an end-to-end CNN can enhance the diagnosis of keratoconus (KC).

Method: The Corvis ST is a non-contact device for in vivo measurement of corneal biomechanics. The CorNet was trained and validated on a dataset consisting of 1786 Corvis ST raw data from 1112 normal eyes and 674 KC eyes.

Enhancing Vault Prediction and ICL Sizing Through Advanced Machine Learning Models.

Purpose: To use artificial intelligence (AI) technology to accurately predict vault and Implantable Collamer Lens (ICL) size.

Methods: The methodology focused on enhancing predictive capabilities through the fusion of machine-learning algorithms. Specifically, AdaBoost, Random Forest, Decision Tree, Support Vector Regression, LightGBM, and XGBoost were integrated into a majority-vote model.

Effect of Intraorbital Mechanical Compression on Retinal Microvascular Perfusion in Quiescent Thyroid-Associated Ophthalmopathy Based on Ocular Biomechanics Measured by Corvis ST.

Introduction: To analyze the correlation between orbital compliance and retinal vessel density (VD) based on dynamic Scheimpflug analyzer (Corvis ST) and optical coherence tomographic angiography (OCT-A).

Methods: In this prospective observational study, 65 eyes of 44 patients with thyroid-associated ophthalmopathy (TAO) in quiescent stage were included (15 males and 29 females). The whole eye movement (WEM) was detected by Corvis ST.

Predictability comparison of sizing parameters for postoperative vault after implantable Collamer lens implantation.

Purpose: This study aims to assess the accuracy of three parameters (white-to-white distance [WTW], angle-to-angle [ATA], and sulcus-to-sulcus [STS]) in predicting postoperative vault and to formulate an optimized predictive model.

Methods: In this retrospective study, a cohort of 465 patients (comprising 769 eyes) who underwent the implantation of the V4c implantable Collamer lens with a central port (ICL) for myopia correction was examined. Least absolute shrinkage and selection operator (LASSO) regression and classification models were used to predict postoperative vault.

Evaluation of changes in corneal biomechanics after orthokeratology using Corvis ST.

Purpose: To investigate the alterations in corneal biomechanical metrics induced by orthokeratology (ortho-k) using Corvis ST and to determine the factors influencing these changes.

Method: A prospective observational study was conducted to analyze various Corvis ST parameters in 32 children with low to moderate myopia who successfully underwent ortho-k lens fitting. Corneal biomechanical measurements via Corvis ST were acquired at six distinct time points: baseline (pre) and 2 h (pos2h), 6 h (pos6h), and 10 h (pos10h) following the removal of the first overnight wear ortho-k, one week (pos1w) and one month (pos1m) subsequent to the initiation of ortho-k.

Performance of Corvis ST Parameters Including Updated Stress-Strain Index in Differentiating Between Normal, Forme-Fruste, Subclinical, and Clinical Keratoconic Eyes.

Purpose: This study seeks to evaluate the ability of the updated stress strain index (SSIv2) and other Corvis ST biomechanical parameters in distinguishing between keratoconus at different disease stages and normal eyes.

Design: Diagnostic accuracy analysis to distinguish disease stages.

Methods: 1084 eyes were included and divided into groups of normal (199 eyes), forme fruste keratoconus (FFKC, 194 eyes), subclinical keratoconus (SKC, 113 eyes), mild clinical keratoconus (CKC-Ⅰ, 175 eyes), moderate clinical keratoconus (CKC-Ⅱ, 204 eyes), and severe clinical keratoconus (CKC-Ⅲ, 199 eyes).

Use of Nanoindentation in Determination of Regional Biomechanical Properties of Rabbit Cornea After UVA Cross-Linking.

Purpose: To evaluate the regional effects of different corneal cross-linking (CXL) protocols on corneal biomechanical properties.

Methods: The study involved both eyes of 50 rabbits, and the left eyes were randomized to the five intervention groups, which included the standard CXL group (SCXL), which was exposed to 3-mW/cm2 irradiation, and three accelerated CXL groups (ACXL1-3), which were exposed to ultraviolet-A at irradiations of 9 mW/cm2, 18 mW/cm2, and 30 mW/cm2, respectively, but with the same total dose (5.4 J/cm2).

Comparison of myopic astigmatic correction after cross-assisted SMILE, FS-LASIK, and transPRK.

Purpose: To compare astigmatic correction among cross-assisted small-incision lenticule extraction (SMILE), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and transepithelial photorefractive keratectomy (transPRK).

Setting: The Eye Hospital of Wenzhou Medical University, Zhejiang, China.

Design: Prospective comparison study.

Assessment of age-related change of the ocular support system.

To estimate the material stiffness of the orbital soft tissue in human orbits using an inverse numerical analysis approach, which could be used in future studies to understand the behaviour under dynamic, non-contact tonometry or simulate various ophthalmological conditions. Clinical data were obtained for the left eye of 185 Chinese participants subjected to a complete ophthalmic examination, including tests by the Corvis ST and Pentacam. 185 numerical models of the eye globes were built with idealised geometry of the sclera while considering the corneal tomography measured by the Pentacam.

Eye movement characteristics and visual fatigue assessment of virtual reality games with different interaction modes.

This study aimed to investigate the eye movement characteristics and visual fatigue of virtual reality games with different interaction modes. Eye movement data were recorded using the built-in eye tracker of the VR device and eye movement parameters were calculated from the recorded raw data. The Visual Fatigue Scales and Simulator Sickness Questionnaire were used to subjectively assess visual fatigue and overall discomfort of the VR experience.

Dynamic topography analysis of the cornea and its application to the diagnosis of keratoconus.

Propose: To establish a dynamic topography analysis method which simulates the dynamic biomechanical response of the cornea and reveals the variations of such response within the corneal surface, and thereafter to propose and clinically evaluate new parameters for the definite diagnosis of keratoconus.

Methods: 58 normal (Normal) and 56 keratoconus (KC) subjects were retrospectively included. Personalized corneal air-puff model was established using corneal topography data by Pentacam for each subject, and the dynamic deformation under air-puff loading was simulated using finite element method, which then enabled calculations of corneal biomechanical parameters of the entire corneal surface along any meridian.

Corneal Epithelial Remodeling in a 6-Month Follow-up Period in Myopic Corneal Refractive Surgeries.

Purpose: To investigate corneal epithelial thickness changes during a 6-month follow-up period after transepithelial photorefractive keratectomy (tPRK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE).

Methods: This prospective study included 76 eyes of 76 participants who underwent myopic refractive surgery (23 FS-LASIK, 22 SMILE, and 31 tPRK). Epithelial thickness and anterior curvature were averaged over 4 regions (subdivided into 25 areas) and measured by spectral-domain optical coherence tomography and Scheimpflug tomography before the operation (pre) and at 1 or 3 days (pos1-3d), 1 week (pos1w), and 1 month (pos1m), 3 months (pos3m), and 6 months (pos6m) postoperatively.

Limitations of Reconstructing Pentacam Rabbit Corneal Tomography by Zernike Polynomials.

The study aims to investigate the likelihood of Zernike polynomial being used for reconstructing rabbit corneal surfaces as scanned by the Pentacam segment tomographer, and hence evaluate the accuracy of corneal power maps calculated from such Zernike fitted surfaces. The study utilised a data set of both eyes of 21 rabbits using a reverse engineering approach for deductive reasoning. Pentacam raw elevation data were fitted to Zernike polynomials of orders 2 to 20.

Introduction and Clinical Validation of an Updated Biomechanically Corrected Intraocular Pressure bIOP (v2).

Purpose: To improve the stability of the Corvis ST biomechanically-corrected intraocular pressure measurements (bIOP) after refractive surgery and its independence of corneal biomechanics.

Methods: A parametric study was carried out using numerical models simulating the behavior of the eye globe under the effects of IOP and Corvis ST external air pressure and used to develop a new algorithm for bIOP; bIOP(v2). It was tested on 528 healthy participants to evaluate correlations with CCT and age.