Purpose: This study aims to introduce and clinically validate a new algorithm that can determine the biomechanical properties of human cornea in vivo. Methods: A parametric was conducted involving representative finite element models ocular globes with wide ranges geometries material behaviour. The were subjected different levels intraocular pressure (IOP) action external air puff produced by non-contact tonometer. Predictions dynamic corneal response under analysed develop an predict...

It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae insert into anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect surface) and scatter intensity throughout depth cornea from centre temporal limbus. The average collagen remained predominantly parallel tissue at all depths. However, in central cornea, spread angles was...

Corneal biomechanics play a fundamental role in the genesis and progression of corneal pathologies, such as keratoconus; remodeling after surgery; affecting measurement accuracy glaucoma biomarkers, intraocular pressure (IOP). Air-puff induced deformation imaging reveals information highlighting normal pathological response to non-contact mechanical excitation. However, current commercial systems are limited monitoring only on one meridian. Here, we present novel custom-developed...

Purpose: To evaluate whether corneal topography map stitching can fully substitute the traditional single-shot capture methods in clinical settings. Methods: This record review study involved measurement of surfaces from 38 healthy subjects using two instruments: Medmont Meridia, which employs a composite method, and Eye Surface Profiler (ESP), device. Data were processed separately for right left eyes, with multiple gaze directions captured by registration geometric transformation...

The organization of scleral collagen helps to determine the eye's biomechanical response intraocular pressure (IOP), and may therefore be important in glaucoma. This study provides a quantitative assessment changes fibril bead-induced murine experimental glaucoma.Wide-angle X-ray scattering was used effect glaucoma on posterior one eye 12 CD1 mice, with untreated fellow eyes serving as controls. Three parameters were measured: local preferred directions, degree anisotropy, total fibrillar...

This paper aims to present a novel full-eye biomechanical material model that incorporates the characteristics of ocular tissues at microstructural level, and use analyse age-related stiffening in tissue behaviour. The collagen content tissues, as obtained using X-ray scattering measurements, was represented by sets Zernike polynomials covered both cornea sclera, then used reconstruct maps fibril magnitude orientation on three-dimensional geometry eye globe. Fine-mesh finite-element (FE)...

Purpose To introduce a new method to map the mechanical stiffness of healthy and keratoconic corneas. Methods Numerical modeling based on finite element was used carry out inverse analysis simulated corneas determine regional variation across corneal surface established trends in collagen fibril distribution. The Stress–Strain Index (SSI), developed validated an earlier study presented as parameter that can estimate overall stress–strain behavior tissue, adopted this research measure...

The study of corneal biomechanics in vivo has been evolving fast recent years. While an organised structure is necessary for its transparency, resistance to occasional external insults and bearing the intraocular pressure (IOP), which several clinically relevant events can disturb. This review focuses on three techniques that are available clinical use, namely Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY, USA), Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany)...

Purpose To assess the biomechanical deterioration arising from keratoconus progression in-vivo.Methods The preoperative examinations of 32 progressive KC cases that were submitted to corneal cross-linking evaluated. included tomography using Pentacam HR and parameters assessed by Corvis ST (Oculus, Wetzlar, Germany). results recorded at two time points, latter which was last visit before CXL procedure. Keratoconus characterised a significant change in ABCD system.Results At follow-up (41.4 ±...

This study aims to illustrate the design, fabrication, and optimisation of an ultrasonic welding (UW) machine join copper wires with non-woven PVC textiles as smart textiles. The explicitly evaluates UW parameters' impact on heat generation, joint strength, electrical properties, a comprehensive understanding process dynamics developing predictive model applicable methodological approach involved designing manufacturing piezoelectric transducer using ABAQUS finite element analyses (FEA)...

A quantitative map of collagen fibril orientation across the human eyeball coat, including both cornea and sclera, has been obtained using a combination synchrotron wide-angle X-ray scattering (WAXS) three-dimensional point mapping. macromolecular crystallography beamline, in custom-modified fibre diffraction setup, was used to record 1.6 nm intermolecular equatorial reflection from fibrillar at 0.5 mm spatial resolution flat-mounted coat. Fibril orientation, derived as an average measure...

To evaluate the characteristics of corneal material properties in healthy individuals and keratoconic patients using stress-strain index (SSI).Vincieye Clinic Milan, Italy, Instituto de Olhos Renato Ambrósio Rio Janeiro, Brazil.Retrospective observational cross-sectional study.Records 1221 were divided into 3 groups: corneas (n = 728), bilateral keratoconus (KC, n 388), very asymmetric ectasia (VAE, 105) when presented with clinical 1 eye normal topography (VAE-NT) fellow eye. All examined...

Purpose: To investigate corneal densitometry artefacts found in Pentacam Scheimpflug scans and their potential effect on assessing keratoconic (KC) corneas compared to normal (N) corneas. Methods: The current study utilises data of 458 N eyes, aged 35.6 ± 15.8 (range 10–87), referred as the “N group”, 314 KC 31.6 10.8 10–72), “KC where were extracted analysed via a custom-built MATLAB code. Radial summations calculated at diameters ranging from 0.5 mm 5.0 mm. minimum normalised radial...

Purpose: To improve the effectivity of patient-specific finite element analysis (FEA) to predict refractive power change (RPC) in rigid Ortho-K contact lens fitting. Novel eyelid boundary detection is introduced FEA model better effects lid on performance, and stress strain outcomes are investigated identify most effective components use modelling. Methods: The current study utilises fully anonymised records 249 eyes, 132 right 117 left eyes from subjects aged 14.1 ± 4.0 years average (range...

Purpose: The purpose of this study is to provide better understanding the Ocular Response Analyzer (ORA) and how reliable it produce intraocular pressure (IOP) measurements that are free effects corneal stiffness parameters, estimates independent IOP.Materials Methods: A numerical parametric closely represents in-vivo conditions human eye ORA procedure was conducted determine correlation coefficient r2 between output values true IOP a number namely thickness, curvature age. For exercise, put...

To present a novel non-parametric algorithm for detecting the position of human eye limbus in three dimensions and new dynamic method measuring full 360° visible iris boundary known as white-to-white distance along horizontal line.The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 females 41 males. Clinical characteristics, height data apex coordinates 1024×1280 pixel digital images eyes were taken by an Eye Surface Profiler processed custom-built MATLAB codes. A light...

Purpose To introduce and clinically validate a new method of estimating intraocular pressure (IOP) in patients with keratoconus soft corneas the aim significantly reducing dependence on corneal biomechanics. Setting Vincieye Clinic, Milan, Italy, Rio de Janeiro Corneal Tomography Biomechanics Study Group, Brazil. Design Retrospective case series. Method This study comprised participants enrolled at two hospitals continents. Numerical analysis based finite element was performed to simulate...

To present a three-dimensional non-parametric method for detecting scleral asymmetry using corneoscleral topography data that are free of edge-effect artefacts.The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 women and 41 men. The eye were exported from the Eye Surface Profiler software in MATLAB binary container format then processed by custom built codes entirely independent profiler software. Scleral was determined initially unprocessed before being again after...

A novel method to locate the centre of keratoconus (KC) and transition zone between pathological area rest corneal tissue is proposed in this study. spherical coordinate system was used generate a height map measured relative optimal sphere fit, normal surface. The cone defined as point with maximum height. Second derivatives were then estimate pathology an iterative process. There mirror symmetry locations both eyes. mean distance apex 1.45 ± 0.25 mm (0.07–2.00), surface 37 23 µm (2–129) 75...

To evaluate the impact of soft contact lens eye-fit on optical power by computational modelling and to produce correction maps for reversing this during design process.Finite element models spherical toric hydrogel lenses at varying nominal powers -20 D +20 D, base curves radii (R1b) 8.2, 8.5, 8.8 mm, overall diameters (d3) 14.5, 15.0, 15.5 mm were generated. Lenses fitted eye generated with human eyes' topography data. Combined eye-lens simulations run under boundary conditions tears'...

To investigate whether Pentacam densitometry readings are affected by corneal tilt.In a prospective study, the right eyes of 86 healthy participants aged 42.8 ± 20.0 years (range 18-79 years) were imaged using Scheimpflug tomography. Elevation maps exported to calculate tilt custom-made software, and acquired directly from analysis add-on standard software Oculus HR. Simple mediation was applied study age as confounding factor in correlation between densitometry.Corneal not independent one...

Background: The aim is to investigate induced higher-order aberrations (HOA)s and astigmatism as a result of non-toric ortho-k lens decentration utilise artificial intelligence (AI) predict its magnitude direction. Methods: Medmont E300 Video topographer was used scan 249 corneas before after wear. Custom-built MATLAB codes extracted topography data determined from the boundary midpoint central flattened treatment zone (TZ). An evaluation carried out by conducting Zernike polynomial fittings...

To investigate the potential improvement in visual acuity and subjective perception of image quality patients with keratoconus using non-orthogonal correction (NOC) cylinder trial lenses where steep flat power meridians are set at angles less or greater than 90°.

Purpose: To identify the relative positions of geometrical and visual axes eye present a method to locate center when axis is taken as reference.Methods: Topography elevation data was collected using Pentacam HR ® topographer from 2040 normal eyes 1020 healthy participants in Brazil, China Italy. A three-dimensional, rotation algorithm, first-order Zernike polynomial fit nonlinear least-squares error function used within an optimization each eye.Results: The right were significantly more...