Investigation of crystalline lens overshooting: ex vivo experiment and optomechanical simulation results

Introduction: Crystalline lens overshooting refers to a situation in which the lens momentarily shifts too much from its typical location immediately after stopping the rotational movement of the eye globe. This movement can be observed using an optical technique called Purkinje imaging.Methods: In this work, an experimental setup was designed to reproduce this effect ex vivo using a fresh porcine eye. The sample was rotated 90° around its centroid using a high-velocity rotation stage, and the Purkinje image sequences were recorded, allowing us to quantify the overshooting effect. The numerical part of the study consisted of developing a computational model of the eye, based on the finite element method, that allowed us to understand the biomechanical behavior of the different tissues in this dynamic scenario. A 2D fluid–structure interaction model of the porcine eye globe, considering both the solid parts and humors, was created to reproduce the experimental outcomes.Results: Outputs of the simulation were analyzed using an optical simulation software package to assess whether the mechanical model behaves optically like the real ex vivo eye. The simulation predicted the experimental results by carefully adjusting the mechanical properties of the zonular fibers and the damping factor.Conclusion: This study effectively demonstrates the importance of characterizing the dynamic mechanical properties of the eye tissues to properly comprehend and predict the overshooting effect

PCI wysokiego ryzyka w przebiegu ostrej niedokrwiennej niewydolności serca na wsparciu ECMO oraz IABP

Percutaneous coronary interventions (PCI) in patients with complex coronary lesions are associated with the higher risk of complications during the procedure. Cardiogenic shock, severe heart failure or ventricular arrhythmias are the most common clinical factors that additionally increase the risk. To improve prognosis, during high risk PCI procedures mechanical circulatory system can be used. We present a case of multivessel percutaneous coronary intervention in high-risk acute ischemic heart failure in 72-year-old woman with complex coronary artery lesions. Due to the high risk, PCI procedure was performed with the ECMO support on the top of intra-aortic balloon pump treatment. A case report was supplemented by a discussion on the use of mechanical circulatory support during high-risk PCI procedures.Zabiegi przezskórnej interwencji wieńcowej (PCI) u pacjentów ze złożonymi zmianami tętnic wieńcowych obarczone są dużym ryzykiem powikłań okołozabiegowych. Klinicznymi czynnikami zwiększającymi ryzyko najczęściej są wstrząs kardiogenny, zaawansowana niewydolność serca oraz komorowe zaburzenia rytmu. Poprawa rokowania pacjentów poddawanych zabiegom PCI wysokiego ryzyka możliwa jest dzięki zastosowaniu systemów do mechanicznego wspomagania krążenia. Przedstawiono przypadek wielonaczyniowej przezskórnej interwencji wieńcowej wysokiego ryzyka w przebiegu ostrej niedokrwiennej niewydolności serca u 72-letniej chorej ze złożonymi zmianami w tętnicach wieńcowych. Z uwagi na wysokie ryzyko zabiegu, zabieg wykonano w zabezpieczeniu ECMO wraz ze stosowaną u pacjentki od kilku dni kontrapulsacją wewnątrzaortalną. Opis przypadku uzupełniono omówieniem zastosowania wspomagania krążenia podczas zabiegów PCI wysokiego ryzyka

Projecting ocean acidification impacts for the Gulf of Maine to 2050: new tools and expectations

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Siedlecki, S. A., Salisbury, J., Gledhill, D. K., Bastidas, C., Meseck, S., McGarry, K., Hunt, C. W., Alexander, M., Lavoie, D., Wang, Z. A., Scott, J., Brady, D. C., Mlsna, I., Azetsu-Scott, K., Liberti, C. M., Melrose, D. C., White, M. M., Pershing, A., Vandemark, D., Townsend, D. W., Chen, C,. Mook, W., Morrison, R. Projecting ocean acidification impacts for the Gulf of Maine to 2050: new tools and expectations. Elementa: Science of the Anthropocene, 9(1), (2021): 00062, https://doi.org/10.1525/elementa.2020.00062.Ocean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high productivity, particularly near the coast where local processes impart a strong influence. Two main regions within the GOM currently experience carbonate conditions that are suboptimal for many organisms—the nearshore and subsurface deep shelf. OA trends over the past 15 years have been masked in the GOM by recent warming and changes to the regional circulation that locally supply more Gulf Stream waters. The region is home to many commercially important shellfish that are vulnerable to OA conditions, as well as to the human populations whose dependence on shellfish species in the fishery has continued to increase over the past decade. Through a review of the sensitivity of the regional marine ecosystem inhabitants, we identified a critical threshold of 1.5 for the aragonite saturation state (Ωa). A combination of regional high-resolution simulations that include coastal processes were used to project OA conditions for the GOM into 2050. By 2050, the Ωa declines everywhere in the GOM with most pronounced impacts near the coast, in subsurface waters, and associated with freshening. Under the RCP 8.5 projected climate scenario, the entire GOM will experience conditions below the critical Ωa threshold of 1.5 for most of the year by 2050. Despite these declines, the projected warming in the GOM imparts a partial compensatory effect to Ωa by elevating saturation states considerably above what would result from acidification alone and preserving some important fisheries locations, including much of Georges Bank, above the critical threshold.This research was financially supported by the Major Special Projects of the Ministry of Science and Technology of China (2016YFC020600), the Young Scholars Science Foundation of Lanzhou Jiaotong University (2018033), and the Talent Innovation and Entrepreneurship Projects of Lanzhou (2018-RC-84)

Optical coherence tomography for quantitative surface topography

We address the measurement and correction of fan distortion in optical coherence tomography (OCT). This effect arises from the scanning system configuration and prevents one, in general, from obtaining quantitative topographic data from OCT. Computer simulations allowed us to quantify the effect and evaluate its dependence on the scanning mirror separation and design of the collimating lens, as well as to estimate the optimal axial position of that lens to minimize the fan distortion. We also developed a numerical algorithm based on 3-D ray propagation for the correction of the residual fan distortion. The effect was studied experimentally using a custom developed time-domain OCT in a Michelson configuration provided with a confocal channel, and the accuracy of the fan distortion correction algorithm tested on samples of known dimensions (flat surfaces and spherical lenses). With a proper calibration of the system with use of an onfocal channel, this algorithm makes it possible for time-domain OCT devices to be used as topographers. copy; 2009 Optical Society of America.This research was funded by grants FIS2008- 02065 and PETRI PET-2006-0478 (Ministerio de Ciencia e Innovación, Spain) to Susana Marcos; EURYI-05-102-ES (EURHORCs-ESF) to Susana Marcos; CSIC JAE-Programs to Damian Siedlecki and Laura Remón; and Alcon, Spain, to Sergio Ortiz.Peer Reviewe

Three-dimensional ray tracing on Delaunay-based reconstructed surfaces

A method of ray tracing for free-form optical surfaces has been developed. The ray tracing through such surfaces is based on Delaunay triangulation of the discrete data of the surface and is related to finite-element modeling. Some numerical examples of applications to analytical, noisy, and experimental free-form surfaces (in particular, a corneal topography map) are presented. Ray-tracing results (i.e., spot diagram root-mean-square error) with the new method are in agreement with those obtained using a modal fitting of the surface, for sampling densities higher than 40 × 40 elements. The method competes in flexibility, simplicity, and computing times with standard methods for surface fitting and ray tracing. © 2009 Optical Society of America.Peer Reviewe

Optical performance of the eye with progressive addition lens correction

The aim of this study was to simulate the retinal image of the eye with progressive addition lens (PAL), correction (without cylindrical component) and investigate its quality. The optical design and analysis software was used in simulation. The topographical data of the front surface of PAL were taken from the scanning profilometry. Also the coordinates of the points of the distant and near power measurements were taken from topographical measurements. The back surface was assumed to be spherical with a radius of curvature matched so that the optical power of PAL meets the data given by the manufacturer. In order to describe the retinal image quality, various metrics were calculated in comparison to the eye without correction. © 2009 Elsevier GmbH. All rights reserved.Authors would like to thank PrzemysŁaw Kolinka from the Institute of Production Engineering and Automation, Wroclaw University of Technology, for carrying out the topographical measurements.Peer Reviewe

Three-dimensional reconstruction of the crystalline lens gradient index distribution from OCT imaging

We present an optimization method to retrieve the gradient index (GRIN) distribution of the in-vitro crystalline lens from optical path difference data extracted from OCT images. Three-dimensional OCT images of the crystalline lens are obtained in two orientations (with the anterior surface up and posterior surface up), allowing to obtain the lens geometry. The GRIN reconstruction method is based on a genetic algorithm that searches for the parameters of a 4-variable GRIN model that best fits the distorted posterior surface of the lens. Computer simulations showed that, for noise of 5 μm in the surface elevations, the GRIN is recovered with an accuracy of 0.003 and 0.010 in the refractive indices of the nucleus and surface of the lens, respectively. The method was applied to retrieve threedimensionally the GRIN of a porcine crystalline lens in vitro. We found a refractive index ranging from 1.362 in the surface to 1.443 in the nucleus of the lens, an axial exponential decay of the GRIN profile of 2.62 and a meridional exponential decay ranging from 3.56 to 5.18. The effect of GRIN on the aberrations of the lens also studied. The estimated spherical aberration of the measured porcine lens was 2.87 μm assuming a homogenous equivalent refractive index, and the presence of GRIN shifted the spherical aberration toward negative values (-0.97 μm), for a 6-mm pupil. © 2010 Optical Society of America.The authors acknowledge funding from (Ministerio de Ciencia e Innovación) grants FIS2008- 02065 and and EURYI-05-102-ES (EURHORCs-ESF) to SM; CSIC I3P Program to AdC; CSIC JAE-Doc Program to DS.Peer Reviewe

Optical Coherence Tomography as a Tool for Ocular Dynamics Estimation

Purpose. The aim of the study is to demonstrate that the ocular dynamics of the anterior chamber of the eye can be estimated quantitatively by means of optical coherence tomography (OCT). Methods. A commercial high speed, high resolution optical coherence tomographer was used. The sequences of tomographic images of the iridocorneal angle of three subjects were captured and each image from the sequence was processed in MATLAB environment in order to detect and identify the contours of the cornea and iris. The data on pulsatile displacements of the cornea and iris and the changes of the depth of the gap between them were retrieved from the sequences. Finally, the spectral analysis of the changes of these parameters was performed. Results. The results of the temporal and spectral analysis manifest the ocular microfluctuation that might be associated with breathing (manifested by 0.25 Hz peak in the power spectra), heart rate (1–1.5 Hz peak), and ocular hemodynamics (3.75–4.5 Hz peak). Conclusions. This paper shows that the optical coherence tomography can be used as a tool for noninvasive estimation of the ocular dynamics of the anterior segment of the eye, but its usability in diagnostics of the ocular hemodynamics needs further investigations