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The cornea is the optical window to the brain. Its optical and structural properties are responsible for optical transparency and vision. The shape, elasticity, rigidity or stiffness are given by its biomechanical properties, whose stability results in ocular integrity and intraocular pressure dynamics. Here, we report in vivo observation of structural changes and biomechanical alterations of the human cornea induced by acoustic wave pressure within the frequency range of 50-350 Hz and 90 dB of sound pressure level. Central corneal thickness (CCT) and eccentricity (e2) were measured using Scheimpflug imaging and biomechanical properties [corneal hysteresis (CH) and intraocular pressure (IOP] were assessed with air-puff tonometry in 6 young healthy subjects. At the specific 150 Hz acoustic frequency, the variation in CCT and e2 were of 0.058 and 7.33 µm, respectively. Biomechanical alterations were also observed in both IOP (decrease of 3.60 mmHg) and CH that showed an increase of 0.40 mmHg.

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye. Methods: Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: IOL in their designed position and flipped. The Atchison theoretical model eye used. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the Modulation Transfer Function (MTF) and Zernike wavefront aberration coefficients of defocus, astigmatism and primary coma were used. Results: Off-centering and tilting the IOL reduced overall MTF values, and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt. Conclusion: The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Peripheral refraction can lead to the development of myopia. The aim of this study was to compare relative peripheral refraction (RPR) in the same cohort of uncorrected (WCL) and corrected eyes with two different soft contact lenses (CL) designed for myopia control, and to analyze RPR depending on the patient’s refraction. A total of 228 myopic eyes (114 healthy adult subjects) (−0.25 D to −10.00 D) were included. Open-field autorefraction was used to measure on- and off- axis refractions when uncorrected and corrected with the two CLs (dual focus (DF) and extended depth of focus (EDOF)). The RPR was measured every 10° out to 30° in a temporal-nasal orientation and analyzed as a component of the power vector (M). The average RPR for all subjects was hyperopic when WCL and when corrected with EDOF CL design, but changed to a myopic RPR when corrected with DF design. Significant differences were found between RPR curves with both CLs in all the eccentricities (Bonferroni correction p < 0.008, except 10°N). An incremental relationship between relative peripheral refraction at 30 degrees and myopia level was found. It is concluded that the two CLs work differently at the periphery in order to achieve myopia control.

Toric intraocular lenses (T-IOLs) may lose their optical quality if they are not correctly positioned inside the capsular bag once implanted. In this work, T-IOLs with cylinder powers of +1.50, +4.50 and +7.50 D and differing degrees of spherical aberration have been designed, manufactured and tested in vitro using a commercial optical bench that complies with the requirements of standard ISO 11979-2. Moreover, the effect of tilt and rotation on optical quality was assessed by means of numerical ray tracing on an astigmatic eye model, while the effect of decentration was evaluated numerically and experimentally.

Purpose The aim of this work is to determinate the effects in the physical parameters in terms of intraocular pressure (IOP) and central corneal thickness (CCT) and corneal biomechanics in terms of corneal resistance factor (CRF) and corneal hysteresis (CH) of wearing silicone-hydrogel soft contact lenses (SiH-CLs) in young adult subjects during a short-term follow-up. Methods 40 eyes of 20 healthy patients with a mean age of 22.87 ± 4.14 were involved in this study. Subjects with corneal diseases, dry eye, irregular astigmatism or who have been previous contact lens wearers were excluded. The ocular response analyzer (Reichert Ophthalmic Instruments) was used to measure CH, CRF and IOP and Scheimpflug imaging (the GALILEI™ Dual Scheimpflug camera analyzer, Ziemer) was used to measure CCT before and 10 days (Group 1) and 20 days (Group 2) after wearing the SiH-CLs. Results IOP was significantly decreased 10 days after using the SiH-CLs (p = 0.009). Within the 20 days' period, Group 2 revealed an even more pronounced decrease in IOP (p = 0.003) while CH increased significantly (p = 0.04). CCT and CRF did not show a significant change during the period of SiH-CLs use. Our finding allowed obtaining an empirical expression that relates IOP, CCT, CRF and CH within a biomechanical compensation experimental model. Conclusions Corneal biomechanical parameters and physical properties of the cornea may be altered due to SiH-CLs use. Our findings could have an impact on the management of glaucoma progression and ocular hypertension.

The structural integrity of the cornea and transparency are critical for normal vision. Corneal evaluation in ophthalmology and clinical research requires fast and user-friendly techniques allowing accurate diagnoses and follow-up of pathologies, injuries or surgery. Macroscopic irregularities in the anterior corneal surface are the main cause of irregular refractive vision problems. The microscopic and nanoscopic irregularities within the three-dimensional architecture of cornea are the cause of loss of optical transparency and scattering. In this review, the state of the art of the different corneal imaging techniques with three-dimensional capabilities will be detailed and discussed according to the descriptive level of analysis: macroscopic, microscopic and nanoscopic scales.

The optical quality of an image depends on both the optical properties of the imaging system and the physical properties of the medium in which the light travels from the object to the final imaging sensor. The analysis of the point spread function of the optical system is an objective way to quantify the image degradation. In retinal imaging, the presence of corneal or cristalline lens opacifications spread the light at wide angular distributions. If the mathematical operator that degrades the image is known, the image can be restored through deconvolution methods. In the particular case of retinal imaging, this operator may be unknown (or partially) due to the presence of cataracts, corneal edema, or vitreous opacification. In those cases, blind deconvolution theory provides useful results to restore important spatial information of the image. In this work, a new semi-blind deconvolution method has been developed by training an iterative process with the Glare Spread Function kernel based on the Richardson-Lucy deconvolution algorithm to compensate a veiling glare effect in retinal images due to intraocular straylight. The method was first tested with simulated retinal images generated from a straylight eye model and applied to a real retinal image dataset composed of healthy subjects and patients with glaucoma and diabetic retinopathy. Results showed the capacity of the algorithm to detect and compensate the veiling glare degradation and improving the image sharpness up to 1000% in the case of healthy subjects and up to 700% in the pathological retinal images. This image quality improvement allows performing image segmentation processing with restored hidden spatial information after deconvolution.

La cirugía de catarata es, desde hace décadas, la intervención quirúrgica más realizada en todo el mundo. Los requisitos actuales no solo se centran en la retirada del cristalino opacificado y su reemplazo por una lente intraocular (LIO) artificial que permita el paso de luz a la retina, sino que buscan alcanzar una alta calidad visual para el paciente, así como la independencia de otro tipo de ayudas ópticas. En pacientes con astigmatismo corneal previo a la cirugía de catarata, alcanzar el estado de emetropía a través de una LIO es posible únicamente con LIOs tóricas (LIOs-T) que compensan el astigmatismo corneal preoperatorio del paciente. En un mercado, cada vez más amplio, donde se precisa de un gran número de LIOs para abastecer toda la demanda debido al envejecimiento de la población, es vital para una empresa como AJL Ophthalmic S.A. disponer en su catálogo de productos de una LIO-T. La presencia de esta lente, junto con las lentes monofocales ya fabricadas y comercializadas por la empresa, aportará un valor extra y una opción más de tratamiento para aquellos pacientes con astigmatismo corneal que sufran de catarata.En esta Tesis Doctoral se presentan los resultados de diseño, fabricación y control de la calidad óptica de una lente intraocular tórica. El requisito inicial para el desarrollo de esta LIO-T es que pueda ser fabricada en las instalaciones que dispone la empresa AJL Ophthalmic S.A. A partir de estos requisitos, se ha elaborado un estudio de mercado y de patentes disponibles para valorar el estado del arte de las LIOs-T en la industria oftalmológica. El diseño de la LIO-T ha atendido tanto a parámetros ópticos como de hápticos. Se han diseñado diferentes LIOs-T con distinta cantidad de aberración esférica y se ha propuesto un diseño de hápticos en C-loop que proporciona buena estabilidad dentro del saco capsular. Para la evaluación de la calidad óptica y mecánica de las LIOs-T propuestas se han utilizado dispositivos experimentales comerciales basados en las especificaciones de las Normas UNE-EN ISO 11979-2 y 11979-3, respectivamente. Se ha estudiado tanto de manera teórica como experimental la tolerancia de los diferentes diseños frente a descentramientos, inclinaciones y rotaciones. Las medidas de calidad óptica y los parámetros biomecánicos obtenidos con los nuevos diseños de LIOs-T han sido comparados con algunos modelos de LIOs-T comerciales.

The biomechanical stability of intraocular lenses (IOLs) must achieve high-quality optical performance and clinical outcomes after cataract surgery. For this reason, the quality and performance features of the IOLs should be previously analysed following the Standard ISO 11979-2 and ISO 11979-3. The ISO 11979-3 tries to reproduce the behaviour of the IOL in the capsular bag by compressing the lens between two clamps. With this test, it has been demonstrated that the haptic design is a crucial factor to obtain biomechanical stability. Hence, the main goal of this study was to design an aberration-free aspheric IOL and to study the influence of haptic geometry on the optical quality. For that purpose, 5 hydrophobic IOLs with different haptic design were manufactured and their biomechanical stability was compared experimentally and numerically. The IOLs were classified as stiff and flexible designs depending on their haptic geometry. The biomechanical response was measured by means of the compression force, the axial displacement, the angle of contact or contact area, the decentration, the tilt and the strain energy. The results suggest that in vitro and in silico compression tests present similar responses for the IOLs analysed. Furthermore, the flexible IOL designs presented better biomechanical stability than stiff designs. These results were correlated with the optical performance, where the optical quality decreases with worst biomechanical stability. This numerical methodology provides an indisputable advance regarding IOL designs, leading to reduce costs by exploring a feasible space of solutions during the product design process and prior to manufacturing.

Purpose To numerically evaluate and compare the tolerance to misalignment and tilt of aspheric intraocular lenses (IOLs) designed for three eyes: with standard cornea and with simulated corneas after myopic and hyperopic laser ablation surgery. Methods Three aspheric IOLs of +20.00 diopter (D) with different spherical aberration (SA) (Z40) values have been designed using a theoretical model eye. Drastic changes on the theoretical eye anterior corneal asphericity have been performed to simulate myopic and hyperopic refractive surgeries. The effect of IOL misalignment and tilt on the image quality has been evaluated using a commercial optical software design for the three eye models. Image quality was assessed from the modulation transfer function (MTF), root mean square (RMS) values of defocus, astigmatism, coma and spherical aberration (Z40), and retinal images obtained from a visual simulator using an aleatory optotype of 0.00 LogMar visual acuity (VA). Results IOL misalignment and tilt reduced MTF values in general, and increased wavefront aberrations errors. Aberration-free IOLs maintained best the MTF values when misalignments were applied, together with good on-axis optical quality. IOLs with negative SA (Z40) correction decreased the MTF value under 0.43 for misalignments values higher than 0.50 mm with the three corneas. The effect of misalignment on RMS astigmatism and coma was correlated with the IOL SA (Z40) and with the three corneas. Conclusions This theoretical study shows that the largest degradation in image quality arises for the IOL with the highest amount of spherical aberration (Z40). Moreover, it has been found that the aspherical design has a more influential role in misalignment tolerance than in tilt tolerance.

The impact of the intraocular straylight (IOS) on the visual performance and retinal imaging is still a challenging topic. Direct optical methods to measure IOS avoid psychophysical approaches and interaction with the patient. In this work, we developed an optical instrument providing direct imaging measurement of IOS based on the double-pass technology. The system was tested in an artificial eye IOS model constructed with holographic diffusers and validated with theoretical simulations.

The image-forming properties of the eye can be described in terms of wave aberration. Understanding the link between aberrations and the anterior segment geometry is therefore of crucial importance for (i) comprehending how the eye works, (ii) modelling the optics of individual eyes, (iii) optimizing optical solutions, or (iv) designing surgical strategies. The eye has many innate adaptations that minimize optical aberrations. In most normal young eyes, the magnitude of aberrations of the cornea is significantly larger than for the whole eye, indicating a significant role of the crystalline lens in compensating corneal aberrations. However, due to geometrical and structural changes, this ocular compensation gets disturbed in different anterior segment conditions, such as keratoconus, presbyopia, or cataract. Keratoconus progressively degrades the corneal shape and, consequently, vision in the adolescence, with a prevalence of 0.05% in the general population. Meanwhile, presbyopia and cataract are conditions related to aging that affect the structure of the crystalline lens, one referring to a loss in accommodative amplitude (presbyopia) and the other to a progressive loss of transparency (cataract). Presbyopia affects 100% of the population older than 45¿years of age, ...

Purpose To evaluate and compare the effect of misalignment and tilt on the optical performance of different aspheric intraocular lens (IOL) designs. Methods Three aspheric IOLs with a different quantity of spherical aberration (SA) have been designed and the effect of IOL misalignment and tilt on the imaging quality of an eye model has been numerically assessed using a commercial optical design software. The prototypes have been manufactured by lathe turning and tested in vitro using the same optical bench (PMTF, Lambda-X) that complies with International Organization for Standardization standard 11979-2 requirements. Image quality was evaluated from the modulation transfer functions (MTFs), through-focus modulation transfer functions (TF-MTFs), root mean square (RMS) values of defocus, astigmatism and coma, and images of the United States Air Force (USAF) target were taken. A comparison with the optical performance of spherical IOLs has also been performed. Results Intraocular lens misalignment and tilt increased wavefront aberrations; the effect of misalignment on root mean square (RMS) astigmatism and coma was positively correlated with the spherical aberration of the IOL. Aberration-free IOLs showed the highest MTF for all misalignment values and for IOLs with negative SA correction the MTF decays below 0.43 when they are decentered 0.50 mm. Conclusions Aspherical IOLs are more sensitive than spherical IOLs to misalignment or tilt, depending on their SA correction. The optical degradation caused by IOL misalignment had a greater effect on IOL designs with a higher amount of negative spherical aberration. In contrast, the effect of tilt on the optical performance was less sensitive to the IOL design.

AIM: To evaluate the efficacy of Bi-Flex toric intraocular lens(T-IOL)(Medicontur, Medical Engineering, Ltd., Inc.)implantation to correct preexisting astigmatism in patients having cataract surgery. METHODS: This retrospective consecutive study included 22 eyes of 16 patients with more than 2.50 diopters(D)of corneal preexisting astigmatism having cataract. Preoperative and postoperative uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), objective and subjective refraction and keratometric and topographic cylinder were measured. Postoperative the toric IOL axis was evaluated using vector analysis. RESULTS: Postoperatively, subjective refractive cylinder was reduced significant(P0 reduced in magnitude from -0.81±2.02D to -0.12±0.62D(PPP >0.05 for J0 and J45). CONCLUSION: Implantation of the Bi-Flex toric IOL is a safe and effective method to correct the preexisting regular astigmatism(greater than 2.50D).

Optical properties of the cornea are responsible for correct vision; the ultrastructure allows optical transparency, and the biomechanical properties govern the shape, elasticity, or stiffness of the cornea, affecting ocular integrity and intraocular pressure. Therefore, the optical aberrations, corneal transparency, structure, and biomechanics play a fundamental role in the optical quality of human vision, ocular health, and refractive surgery outcomes. However, the inter-relationships of those properties are not yet reported at a macroscopic scale within the hierarchical structure of the cornea. This work explores the relationships between the biomechanics, structure, and optical properties (corneal aberrations and optical density) at a macro-structural level of the cornea through dual Placido–Scheimpflug imaging and air-puff tonometry systems in a healthy young adult population. Results showed correlation between optical transparency, corneal macrostructure, and biomechanics, whereas corneal aberrations and in particular spherical terms remained independent. A compensation mechanism for the spherical aberration is proposed through corneal shape and biomechanics.

[EN] A conceptually new type of corneal inlays for a customized treatment of presbyopia is presented. The diffractive inlay consists on a small aperture disc having an array of micro-holes distributed inside the open zones of a Fresnel zone plate. In this way, the central hole of the disc lets pass the zero order diffraction and produces an extension of the depth of far focus of the eye, while the diffracted light through the holes in the periphery produce the near focus. Additionally, the micro-holes in the inlay surface fulfill the essential requirement of allowing the flow of nutrients through it to the cells of the corneal stroma. Theoretical and optical-bench experimental results for the polychromatic axial Point Spread Function (PSF) were obtained, showing an improved performance compared to the small aperture corneal inlay currently in the market (Kamra). Images of a test object, obtained at several vergences in the surroundings of the far and near foci, are also shown. Picture: Simulation of the appearance of the Diffractive corneal inlay on a real eye., This study was founded by Ministerio de Economia y Competitividad FEDER (Grant DPI2015-71256-R), and by Generalitat Valenciana (Grant PROMETEOII-2014-072), Spain.

[EN] In this work we present a new methodology to create 3D images through the simple images obtained with the slit lamp. The proposed methodology is aimed at students of Optics and Optometry and consists of: 1) Acquisition of images with each eyepiece of the slit-lamp, 2) Fusion of the images obtained with a software developed in MATLAB GUI (Graphical User Interface) and 3) Visualization of the 3D images with the red/green glasses or polarized filters. A didactic level is intended to achieve an improvement in the interpretation of the obtained images with the new methodology. To assess the effectiveness of the technique, the obtained marks in the last two years are compared with those registered in the 2018-2019 academic year in the subject "Optometry Laboratory". As an example, some 3D images of different ocular structures with different techniques are shown. This new methodology could be useful for any area that teaches how to use instruments with binocular microscopes., [ES] En este trabajo se presenta una nueva metodología para la creación de imágenes 3D a través de las imágenes sencillas obtenidas con la lámpara de hendidura. La metodología propuesta esta dirigida a estudiantes de Óptica y Optometría y consiste en: 1) Adquisición de imágenes con cada uno de los oculares de la lámpara de hendidura, 2) Composición de las imágenes 3D con un software desarrollado en MATLAB GUI (Interfaz Gráfica de Usuario y 3) Visualización de las imágenes 3D mediante el uso de gafas rojo/verde o filtros polarizados. A nivel didáctico se pretende conseguir una mejora en la interpretación de las imágenes obtenidas con la nueva metodología. Para valorar la eficacia de la técnica se comparan las notas obtenidas en los dos últimos años con las registradas en el curso académico 2018-2019 en la asignatura de “Laboratorio de Optometría”. A modo de ejemplo, se muestran algunas imágenes 3D de diferentes estructuras oculares con distintas técnicas. Esta nueva metodología podría ser de utilidad para cualquier área que enseñe a emplear instrumentos con microscopios binoculares.

To study the main design parameters that affect the mechanical stability of C-loop intraocular lenses, leading to an optimal design that minimizes the axial displacement, tilt and rotation. A total of 144 geometrical variations were studied on a 1-piece, non-angulated, C-loop hydrophobic acrylate intraocular lens. The study was performed in a finite element modeling simulation. The suitable set of variations was determined using a mixed-factorial analysis, allowing to analyse the impact of the different designs on the mechanical stability of the lens (compression force, axial displacement, tilt and rotation). The design parameters under study were: the length, width, thickness and opening angle of the haptic, the haptic–optic junction and the start of the haptic curvature. The compression (or reaction) force is affected by the haptic width, the haptic–optic junction, and the interaction between both. The axial displacement is mainly affected by the width and thickness of the haptic, and the size of the haptic–optic junction as well. The tilt is affected by the haptic thickness and the interaction between the haptic curvature and the haptic–optic junction. The rotation is affected by the start of the haptic curvature, the haptic–optic junction and the haptic width. The haptic–optic juntion is one of the most influential parameters affecting the four responses studied of the C-Loop IOL. The smaller the haptic–optic juntion, the better biomechanical stability.

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control., LR gratefully acknowledges the financial support of the Ministerio de Economia y Competitividad, Project: (DPI2017-84047-R (MINICO-FEDER)). This research has received funding from the Spanish Government (DTS18/00107) to PPM; PPM also declares Personal Financial Interest (2EyesVision). This project was also supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/SAU-BEB/098392/2008 and PTDC/FIS-OPT/0677/2014 granted to JMG-M, the FCT Strategic Funding UID/FIS/04650/2013 granted to the Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to AA-S.

[EN] This work presents the design and construction of a spectrometer made in the laboratory and the development of mathematical models needed to process and analyze the acquired spectrum. For modeling functions it has been used LabVIEW program. The aim is to bring this type of instrumentation to engineering students from both, physical and mathematical point of view. The application has been successfully integrated in the learning strategies of the course Sensores Fisicos, Master Universitario en Sensores Para Aplicaciones Industriales at the Universitat Politecnica de Valencia. As an example, we have characterized different light sources emitting in different regions of the electromagnetic spectrum., [ES] En este trabajo se presenta el diseño y la construcción de un espectrómetro realizado en el laboratorio y el desarrollo de los modelos matemáticos necesarios para procesar y analizar el espectro adquirido con el mismo. Para la modelización de las funciones se ha utilizado el programa LabVIEW. El objetivo es acercar este tipo de instrumentación a los estudiantes de Ingeniería, tanto desde el punto de vista físico como matemático. La aplicación desarrollada ha sido integrada en la asignatura Sensores Físicos del Máster Universitario en Sensores Para Aplicaciones Industriales de la Universitat Politècnica de València. A modo de ejemplo, se han caracterizado diferentes fuentes de iluminación que emiten en distintas regiones del espectro electromagnético.

[EN] In this work, we present a new concept of IOL design inspired by the demonstrated properties of reduced chromatic aberration and extended depth of focus of Fractal zone plates. A detailed description of a proof of concept IOL is provided. The result was numerically characterized, and fabricated by lathe turning. The prototype was tested in vitro using dedicated optical system and software. The theoretical Point Spread Function along the optical axis, computed for several wavelengths, showed that for each wavelength, the IOL produces two main foci surrounded by numerous secondary foci that partially overlap each other for different wavelengths. The result is that both, the near focus and the far focus, have an extended depth of focus under polychromatic illumination. This theoretical prediction was confirmed experimentally by means of the Through-Focus Modulation Transfer Function, measured for different wavelengths., This study was supported by Ministerio de Economia y Competitividad www.mineco.gob.es/ FEDER (Grant DPI2015-71256-R) and by Generalitat Valenciana www.ceice.gva.es/web/ciencia (Grant PROMETEOII-2014-072), Spain.

[EN] We present a new open experimental setup assisted with LabView to be used to teach the concept of the point spread function (PSF). The PSF describes the response of an image-forming system to a point object. The PSF concept is of fundamental importance in optics since the output of an image-forming system can be simulated as the convolution of the PSF with the input object. In this work, a new graphical user interface has been developed to obtain a real-time measure of the PSF and the corresponding images provided by different lenses and pupils with different sizes and shapes. From a didactical point of view, the proposed method allows students to interpret the results in a visual and heuristic way., This study was supported by the Ministerio de Economia y Competitividad and FEDER (Grant DPI 2015-71256-R) and by Generalitat Valenciana (Grant PROMETEOII/2014/072), Spain.

Contract grant sponsor: Ministerio de Economia y Competividad; Contract grant number: FIS2011-23175; Contract grant sponsor: Generalitat Valenciana; Contract grant number: PROMETEOII/2014/072; Contract grant sponsor: Universitat de Valencia; Contract grant number: UV-SFPIE_DINV14-222801

espanolEl biomiscroscopio o lampara de hendidura permite la observacion de las distintas estructuras que componen el globo ocular mediante diferentes tecnicas de observacion. En este trabajo se presentan dos tecnicas distintas: la reflexion especular que permite la visualizacion de las celulas endoteliales y la dispersion escleral que permite la deteccion de opacidades corneales. EnglishThe slit lamp enables the user to inspect some eye segments by different illumination techniques. One of them, specular reflection, allow the user to evaluate the corneal endothelium. This work shows two photographs about different techniques: specular reflection is valuable for examining the corneal endothelium and scattering sclero-corneal illumination for studying the structure and transparency of the cornea.

[EN] Purpose To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. Methods The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). Results LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response. Conclusions VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation., [ES] Objetivo Investigar el cambio en la agudeza visual (AV) producido por los diferentes tipos de astigmatismo (sobre la base del poder refractivo y la posición de los principales meridianos) en ojos con acomodación normal. Métodos Se utilizó el método de desenfoque inducido con lentes para simular un conjunto de veintiocho situaciones de desenfoque astigmático en diferentes ojos emetrópicos sanos. Además, se simularon veinticuatro valores de defecto esférico en los mismos ojos, a fines comparativos. Se midió la AV en cada caso, representándose los resultados, expresados en unidades logMAR, frente a los módulos del vector de potencia dióptrica (desenfoque). Resultados La escala LogMAR para AV varía de manera lineal, incrementando la distorsión astigmática, dependiendo la inclinación de la línea de la demanda acomodativa en cada tipo de astigmatismo. Sin embargo, en cada caso, no hallamos diferencias significativas entre los tres ejes analizados (0°, 45°, 90°). No se hallaron diferencias estadísticamente significativas en cuanto a la AV lograda con el defecto miópico esférico (MD) y astigmatismo mixto (MA). La AV con astigmatismo hipermetrópico simple (SHA) fue más elevada que con astigmatismo miópico simple (SMA). Sin embargo, en este caso se obtuvieron resultados no concluyentes en términos de significancia estadística. La AV lograda con astigmatismo hipermetrópico compuesto (CHA) se vio altamente influenciada por la respuesta acomodativa del ojo. Conclusiones La AV guarda relación con el desenfoque de modo diferente para cada tipo de astigmatismo, dependiendo de la demanda de acomodación. La AV es mejor cuando una de las líneas focales está en la retina con independencia de la orientación del eje; la acomodación favorece esta situación., This study was supported by the Ministerio de Economía y Competitividad and FEDER (Grant DPI2015-71256-R), and by the Generalitat Valenciana (Grant PROMETEOII-2014-072), Spain.

In this work we introduce a virtual laboratory, APERIODIC DIFFRACT, developed in Matlab GUI (Graphical User Interface) as an informatics tool for teaching the diffractive properties of aperiodic gratings. This GUI allows the student to generate aperiodic sequences by iterating and lets to study the spectra for different iterating orders.

This work presents a new virtual laboratory, OPHTALMIC, developed with MATLAB GUI for using in Optics and Optometry courses as a computer tool for studying the focusing properties of multifocal diffractive both on unconventional structures both periodic and aperiodic. This virtual laboratory enables students to quickly and easily analyze the influence of the different parameters of construction and find the best solution for a user.