Medida de la calidad óptica de lentes intraoculares multifocales in vitro mediante un sistema de paso simple y doble paso modificado

Postprint (author's final draft

Random Changes of Accommodation Stimuli: An Automated Extension of the Flippers Accommodative Facility Test

Postprint (author's final draft

Colorimetric analysis of eye fundus structures with multispectral retinography

The analysis of the eye fundus is critical to prevent retinal and choroidal diseases since most of them cause no symptoms at early stages. Treating them when the very first signs appear is crucial to avoid vision losses. To this end, the color of eye fundus structures of healthy and diseased patients was assessed from images acquired with a novel multispectral fundus camera (400 nm – 1300 nm) with high spectral and spatial resolution. Characteristic color traits were found: in healthy eyes, large CIEDE2000 color differences were reported between arteries and veins due to different blood oxygenation; the contrast of nerve fibers/fovea was enhanced, giving rise to relevant color differences; in eyes with age related macular degeneration, lesions such as drusen could be better distinguished than with traditional color retinography; alterations of the optic disk in patients with glaucoma were also assessed, showing remarkable CIEDE2000 values when compared to healthy patientsThis project has received funding from the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No. 801342 (Tecniospring INDUSTRY) and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ). This research was also supported by the Ministerio de Economía, Industria y Competitividad (MINECO), the Agencia Estatal de Investigación (AEI) and the European Regional Development Fund (FEDER) under the grant DPI2017-89414-R.Peer ReviewedPostprint (published version

An automated and objective cover test to measure heterophoria

Postprint (published version

Response for light scattered in the ocular fundus from double-pass and Hartmann–Shack estimations

Double-pass (DP) and Hartmann--Shack (HS) are complementary techniques based on reflections of light in the ocular fundus that may be used to estimate the optical properties of the human eye. Under conventional data processing, both of these assessment modes provide information on aberrations. In addition, DP data contain the effects of scattering. In the ocular fundus, this phenomenon may arise from the interaction of light with not only the retina, but also deeper layers up to which certain wavelengths may penetrate. In this work, we estimate the response of the ocular fundus to incident light by fitting the deviations between DP and HS estimations using an exponential model. In measurements with negligible intraocular scattering, such differences may be related to the lateral spreading of light that occurs in the ocular fundus due to the diffusive properties of the media at the working wavelength. The proposed model was applied in young healthy eyes to evaluate the performance of scattering in such a population. Besides giving a parameter with information on the ocular fundus, the model contributes to the understanding of the differences between DP and HS estimations.Postprint (author's final draft

Stimulus Unpredictability in Time, Magnitude, and Direction on Accommodation

Postprint (author's final draft

Fast visible and extended nearinfrared multispectral fundus camera

We present a multispectral fundus camera that performs fast imaging of the ocular posterior pole in the visible and near-infrared (400 to 1300 nm) wavelengths through 15 spectral bands, using a flashlight source made of light-emitting diodes, and CMOS and InGaAs cameras. We investigate the potential of this system for visualizing occult and overlapping structures of the retina in the unexplored wavelength range beyond 900 nm, in which radiation can penetrate deeper into the tissue. Reflectance values at each pixel are also retrieved from the acquired images in the analyzed spectral range. The available spectroscopic information and the visualization of retinal structures, specifically the choroidal vasculature and drusen-induced retinal pigment epithelium degeneration, which are hardly visible in conventional color fundus images, underline the clinical potential of this system as a new tool for ophthalmic diagnosis.Peer ReviewedPostprint (published version

Medidas hiperespectrales de fondo de ojo: una nueva herramienta para el diagnóstico oftalmológico

Peer ReviewedPostprint (published version

Quantification of forward scattering based on the analysis of double-pass images in the frequency domain

Preprin

Nuevo sistema de doble-paso compacto con enfoque asimétrico

Every day more people are using multifocal systems to correct presbyopia, as for example contact lenses or intraocular lenses. As a consequence, the necessity to do an appropriate characterization of their optical quality has increased. Due to this situation, the main purpose of this project has been to develop a new compact open-field double-pass system with asymmetric focus that characterizes objectively in vivo the optical quality of multifocal systems that are adapted or implanted in the eye. As a preliminary study, one diffractive and one refractive multifocal lens were implanted in a wet customized model-eye and characterized by this new set-up. Regarding the asymmetric focus of the set-up, a through-focus from +0.75 to -4.00D in steps of 0.25D was performed in the second pass for each tested lens,while the optical power of the first pass remained fixed. Results show that it is possible to distinguish, characterize the different foci of the measured multifocal intraocular lenses implanted in the model eye, and evaluate the optical quality of the system composed by the eye + the multifocal element. Therefore, it has been concluded that this new compact open-field double-pass system with asymmetric focus is suitable to evaluate the optical quality of multifocal systems adapted or implanted in the eye.Cada día más personas usan elementos ópticos multifocales para corregir la presbicia, por ejemplo una lente de contacto o una lente intraocular. En consecuencia, la necesidad de evaluar la calidad óptica del ojo con un elemento corrector multifocal ha adquirido una gran importancia. Dada esta situación, el principal objetivo de este proyecto ha sido desarrollar un nuevo sistema compacto basado en la técnica de doble-paso con enfoque asimétrico capaz de realizar una caracterización objetiva e “in vivo” de la calidad óptica del conjunto ojo-elemento óptico multifocal. En este estudio preliminar se han empleado dos lentes intraoculares multifocales, una difractiva y otra refractiva,implantadas en un ojo artificial. Al ser un sistema con enfoque asimétrico, se utilizó el segundo paso para realizar un barrido desde +0.75 a -4.00D en pasos de 0.25 D manteniendo el primer paso fijo. Los resultados han mostrado que es posible hallar y diferenciar los dos planos de enfoque, lejano y cercano, de las lentes intraoculares multifocales implantadas en el ojo artificial y evaluar la calidad óptica del conjunto ojoelemento multifocal. Por tanto, se ha demostrado la viabilidad de este nuevo sistema compacto de doble-paso con enfoque asimétrico para caracterizar la calidad óptica de un ojo con un elemento óptico multifocal.Postprint (published version