Publications by authors named "Augusto Arias"

7 Publications

  • Page 1 of 1

Straylight in Different Types of Intraocular Lenses.

Transl Vis Sci Technol 2020 11 9;9(12):16. Epub 2020 Nov 9.

Laboratorio de Óptica, Universidad de Murcia, Campus de Espinardo, Murcia, Spain.

Purpose: To show the importance of measuring the angular distribution of straylight as an in vitro test for intraocular lenses (IOLs).

Methods: The optical integration method was implemented to measure the point spread function, up to 5.1°, of IOLs immersed in a wet cell. The straylight parameter was calculated as the product of the point spread function by the squared angle. The effect of the scattered light is shown in extended images of a target surrounded by headlamps as glare sources. Three different IOLs were tested: (1) AcrySof IQ SN60WF, monofocal, (2) AcrySof IQ PanOptix, trifocal, and (3) Tecnis Symfony ZRX00, bifocal with extended depth of focus. Measurements were compared to previously reported clinical studies where the same IOL models were implanted.

Results: The mean amount of scattered light, between 1.0° and 5.1°, generated by each IOLs were, in degsr units: (1) 1.2, (2) 12.1, and (3) 33.4. Lens (3) present a high amount of straylight related to a halo of an approximate diameter of 2°.

Conclusions: In vitro measurements of the angular distribution of the point spread function of different types of IOLs showed important aspects related to their manufacturing quality. These results are in line with previous clinical findings where glare sensitivity was tested in the same angular range.

Translational Relevance: In vitro measurement of angular dependence of straylight in IOLs, regardless their design, provides a valuable feedback to improve their optical quality. The minimization of the amounts of straylight positively impacts the recurrence of photic phenomena.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1167/tvst.9.12.16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7671868PMC
November 2020

Phase-only modulation with two vertical aligned liquid crystal devices.

Opt Express 2020 Nov;28(23):34180-34189

Spatial Light Modulators (SLMs) are widely used in several fields of optics such as adaptive optics. SLMs based on Liquid Crystal (LC) devices allow a dynamic and easy representation of two-dimensional phase maps. A drawback of these devices is their elevated cost, preventing a massive use of the technology. We present a more affordable approach based on the serial arrangement of vertical aligned LC devices, with characteristics of phase modulation similar to a widely used parallel aligned LC device. We discuss the peculiarities of the approach, the performance and some potential areas of applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.410429DOI Listing
November 2020

Recommendations of the Colombian Consensus Committee for the Management of Traumatic Brain Injury in Prehospital, Emergency Department, Surgery, and Intensive Care (Beyond One Option for Treatment of Traumatic Brain Injury: A Stratified Protocol [BOOTStraP]).

J Neurosci Rural Pract 2020 Jan 3;11(1):7-22. Epub 2020 Mar 3.

Neurosurgery and Intensive Care Service, Santa Casa da Misericórdia Hospital in São João del-Rei, São João del-Rei, Minas Gerais, Brazil.

 Traumatic brain injury (TBI) is a global public health problem. In Colombia, it is estimated that 70% of deaths from violence and 90% of deaths from road traffic accidents are TBI related. In the year 2014, the Ministry of Health of Colombia funded the development of a clinical practice guideline (CPG) for the diagnosis and treatment of adult patients with severe TBI. A critical barrier to the widespread implementation was identified-that is, the lack of a specific protocol that spans various levels of resources and complexity across the four treatment phases. The objective of this article is to present the process and recommendations for the management of patients with TBI in various resource environments, across the treatment phases of prehospital care, emergency department (ED), surgery, and intensive care unit.  Using the Delphi methodology, a consensus of 20 experts in emergency medicine, neurosurgery, prehospital care, and intensive care nationwide developed recommendations based on 13 questions for the management of patients with TBI in Colombia.  It is estimated that 80% of the global population live in developing economies where access to resources required for optimum treatment is limited. There is limitation for applications of CPGs recommendations in areas where there is low availability or absence of resources for integral care. Development of mixed methods consensus, including evidence review and expertise points of good clinical practices can fill gaps in application of CPGs. BOOTStraP (Beyond One Option for Treatment of Traumatic Brain Injury: A Stratified Protocol) is intended to be a practical handbook for care providers to use to treat TBI patients with whatever resources are available.  Stratification of recommendations for interventions according to the availability of the resources on different stages of integral care is a proposed method for filling gaps in actual evidence, to organize a better strategy for interventions in different real-life scenarios. We develop 10 algorithms of management for building TBI protocols based on expert consensus to articulate treatment options in prehospital care, EDs, neurological surgery, and intensive care, independent of the level of availability of resources for care.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0040-1701370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7055642PMC
January 2020

Comparison of Two Techniques to Measure Optic Nerve Sheath Diameter in Patients at Risk for Increased Intracranial Pressure.

Crit Care Med 2019 11;47(11):e940

Department of Intensive Care Medicine, Clinica Norte, Cucuta, Colombia, and Critical Care Medicine, Fundacion Universitaria de Ciencias de la Salud FUCS, Bogota, Colombia; Universidad de Pamplona, Colombia, and Department of Intensive Care Medicine, Clinica Norte, Cucuta, Colombia.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/CCM.0000000000003933DOI Listing
November 2019

Light scattering in the human eye modelled as random phase perturbations.

Biomed Opt Express 2018 Jun 11;9(6):2664-2670. Epub 2018 May 11.

Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo (Edificio 34), E-30100, Murcia, Spain.

Light scattering in the eye affects the quality of vision and its effect increases with aging and related pathologies, such as cataracts. Simulating methods were developed in order to reproduce the effects of this phenomenon. We introduce a statistical model of wavefront perturbations at the pupil plane of the eye that replicates the characteristic angular distribution of the light distribution over the retina. Our approach is based on the parameterization of the discrete cosine spectrum of the wavefront perturbation. The model performance was experimentally validated with a dedicated setup using a liquid crystal on silicon device as a spatial phase modulator. This instrument can be used for further visual experiments with controlled induction of light scattering.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/BOE.9.002664DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6154192PMC
June 2018

Performance of a differential contrast sensitivity method to measure intraocular scattering.

Biomed Opt Express 2017 Mar 6;8(3):1382-1389. Epub 2017 Feb 6.

Laboratorio de Optica, Universidad de Murcia, Campus de Espinardo (Ed 34), 30100 Murcia, Spain.

Increased intraocular scatter degrades quality of vision, especially in the presence of glare sources. Standard tests, such as visual acuity, are not well suited to capture this condition. There are specific methods to measure intraocular scatter, but require dedicated instruments. In this work, we propose a method to estimate the amount of scatter by combining to sequential measurements of the contrast sensitivity function for two conditions, with and without a glare source. We applied the approach in a group of young subjects with no know ocular pathology fitted with photographic diffusing filters. The straylight estimates were compared with those provided by two alternative techniques, one based on the compensation comparison method and the other the optical integration. The results obtained with the three approaches were in a good agreement, demonstrating the feasibility of the proposed method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/BOE.8.001382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480550PMC
March 2017

Through-focus response of multifocal intraocular lenses evaluated with a spatial light modulator.

Appl Opt 2012 Dec;51(36):8594-8

Centro de Tecnologías Físicas, Universitat Politècnica de València, Valencia, Spain.

A new testing technique based on the use of a liquid crystal spatial light modulator (SLM) is proposed to analyze the optical quality of multifocal intraocular lenses (MIOLs). Different vergences and decentrations of the incident beam can be programmed onto the SLM in order to record the point spread function (PSF) for different object positions. From these axial PSFs, the through-focus modulation transfer function is computed. Because there are no moving parts in the experimental setup, this method is fast and versatile to assess MIOLs. Experimental results confirm the potential of the proposed method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/AO.51.008594DOI Listing
December 2012