Search

The eye is an optical element that projects images of the world onto the retina. This optical system is not perfect, as it suffers from aberrations as well as diffraction and scattering that degrade retinal image quality. In recent years, a large number of techniques based on Adaptive Optics (AO) have been developed for the measurement and correction of ocular aberrations. Measurements of the eye with AO systems have allowed a better understanding of the contribution of the different components of the eye to the degradation of image quality. Furthermore, the manipulation of optical aberrations allows understanding of the connections between optical degradation and perceived visual quality. The optics of the eye change with age, eye diseases, and treatments. Therefore, understanding the sources of variations in natural aberrations, the interactions between monochromatic aberrations and chromatic aberrations (Longitudinal Chromatic Aberration 'LCA' and Transverse Chromatic Aberration 'TCA'), and the impact of optical blurring on vision is key. This knowledge allows to shed light on some basic mechanisms of the eye and, among others, to guide the design and optimization of new alternatives for the correction of presbyopia (multifocal intraocular lenses and multifocal contact lenses), as well as other more complex personalized refractive and presbyopic corrections. Visual simulators based on AO are excellent tools to investigate vision under natural and modified optics in monochromatic and polychromatic conditions. A wavefront sensor in combination with an active optical element (deformable mirror, spatial light modulator, or simultaneous vision simulators based on SimVis technology) and a psychophysical channel allows investigating the optics of the eye, the neural adaptation processes behind, and the response to modified or simulated optics. In addition to modifying the optics using active elements, it can also be done using Fourier optics, convolving the PSF (Point S, El ojo es un elemento óptico que proyecta imágenes del mundo en la retina. Este sistema óptico no es perfecto, ya que sufre de aberraciones, así como difracción y dispersión que degradan la calidad de la imagen retiniana. En los últimos años, se han desarrollado un gran número de técnicas basadas en Óptica Adaptativa (AO) para la medida y corrección de las aberraciones oculares. Las mediciones del ojo con sistemas de AO han permitido comprender mejor la contribución de los diferentes componentes del ojo a la degradación de la calidad de las imágenes. Además, la manipulación de las aberraciones ópticas permite comprender las conexiones entre la degradación óptica y la calidad visual percibida. La óptica del ojo cambia con la edad, las enfermedades oculares y los tratamientos. Por lo tanto, comprender las fuentes de variaciones de las aberraciones naturales, las interacciones entre las aberraciones monocromáticas (HOA) y cromáticas (Aberración cromática longitudinal 'LCA' y Aberración cromática transversal 'TCA') y el impacto de la borrosidad óptica en la visión es decisivo. Este conocimiento permite arrojar luz sobre algunos mecanismos básicos del ojo y, entre otros, orientar el diseño y optimización de nuevas alternativas para la corrección de la presbicia (lentes intraoculares y lentes de contacto multifocales) , así como otras correcciones refractivas más complejas y personalizadas. Los simuladores visuales basados en la AO son excelentes herramientas para investigar la visión bajo ópticas naturales y modificadas en condiciones monocromáticas y policromáticas. Un sensor de frente de onda en combinación con un elemento óptico activo (espejo deformable, modulador espacial de luz o simuladores de visión simultánea basados en la tecnología SimVis) y un canal psicofísico permite investigar la óptica del ojo, los procesos de adaptación neural detrás de él y la respuesta a la óptica modificada o simulada. Además de modificar la óptica mediante elementos activos se puede

Visual simulators aim at evaluating vision with ophthalmic corrections prior to prescription or implantation of intraocular lenses (IOLs) in the patient’s eye. In the present study, we present the design, implementation, and validation of a new IOL-in-cuvette channel in an Adaptive Optics visual simulator, which provides an alternative channel for pre-operative simulation of vision with IOLs. IOL-in-cuvette is projected to the pupil’s plane of the subject by using a Rassow system. A second lens, the Rassow lens, compensates for an IOL of 20 D while other powers can be corrected with a Badal system in a 5 D range. The new channel was evaluated by through-focus (TF) optical quality on an artificial eye on bench, and by TF visual acuity in patients, with various IOL designs (monofocal, diffractive trifocal, and refractive extended depth of focus).

The eye is an optical element that projects images of the world onto the retina. This optical system is not perfect, as it suffers from aberrations as well as diffraction and scattering that degrade retinal image quality. In recent years, a large number of techniques based on Adaptive Optics (AO) have been developed for the measurement and correction of ocular aberrations. Measurements of the eye with AO systems have allowed a better understanding of the contribution of the different components of the eye to the degradation of image quality. Furthermore, the manipulation of optical aberrations allows understanding of the connections between optical degradation and perceived visual quality. The optics of the eye change with age, eye diseases, and treatments. Therefore, understanding the sources of variations in natural aberrations, the interactions between monochromatic aberrations and chromatic aberrations (Longitudinal Chromatic Aberration 'LCA' and Transverse Chromatic Aberration 'TCA'), and the impact of optical blurring on vision is key. This knowledge allows to shed light on some basic mechanisms of the eye and, among others, to guide the design and optimization of new alternatives for the correction of presbyopia (multifocal intraocular lenses and multifocal contact lenses), as well as other more complex personalized refractive and presbyopic corrections. Visual simulators based on AO are excellent tools to investigate vision under natural and modified optics in monochromatic and polychromatic conditions. A wavefront sensor in combination with an active optical element (deformable mirror, spatial light modulator, or simultaneous vision simulators based on SimVis technology) and a psychophysical channel allows investigating the optics of the eye, the neural adaptation processes behind, and the response to modified or simulated optics. In addition to modifying the optics using active elements, it can also be done using Fourier optics, convolving the PSF (Point S

We evaluated the interaction of multifocal patterns with eye's accommodation. Seven patterns were mapped on the spatial light modulator and the deformable mirror of an adaptive optics visual simulator, and projected onto the subjects' eyes, representing different contact lens designs: NoLens, Bifocal Center Distance (+2.50D), Bifocal Center Near (+2.50D) and Multifocal Center Near-MediumAdd (+1.75D) and Center Near HighAdd (+2.50D), positive and negative spherical aberration (±1µm). The change in spherical aberration and the accommodative response to accommodative demands were obtained from Hartmann-Shack measurements. Positive spherical aberration and Center Distance designs are consistent with a higher accommodative response (p=0.001 & p=0.003): steeper shift of SA towards negative values and lower accommodative lag.

Purpose : There is an association between myopia progression and near work that has led to speculation that the larger accommodative lags reported in myopes may be a factor or an effect in progression. We evaluated the impact of contact lenses design and addition on the accommodative behavior in myopes

Adaptive optics (AO) visual simulators are excellent platforms for non-invasive simulation visual performance with new intraocular lens (IOL) designs, in combination with a subject own ocular aberrations and brain. We measured the through focus visual acuity in subjects through a new refractive IOL physically inserted in a cuvette and projected onto the eye's pupil, while aberrations were manipulated (corrected, or positive/negative spherical aberration added) using a deformable mirror (DM) in a custom-developed AO simulator. The IOL increased depth-of-focus (DOF) to 1.53 ± 0.21D, while maintaining high Visual Acuity (VA, -0.07 ± 0.05), averaged across subjects and conditions. Modifying the aberrations did not alter IOL performance on average.

Convolved images are often used to simulate the effect of ocular aberrations on image quality, where the retinal image is simulated by convolving the stimulus with the point spread function derived from the subject's aberrations. However, some studies have shown that convolved images are perceived far more degraded than the same image blurred with optical defocus. We hypothesized that the positive interactions between the monochromatic and chromatic aberrations in the eye are lost in the convolution process. To test this hypothesis, we evaluated optical and visual quality with natural optics and with convolved images (on-bench, computer simulations, and visual acuity [VA] in subjects) using a polychromatic adaptive optics system with monochromatic (555 nm) and polychromatic light (WL) illumination. The subject's aberrations were measured using a Hartmann Shack system and were used to convolve the visual stimuli, using Fourier optics. The convolved images were seen through corrected optics. VA with convolved stimuli was lower than VA through natural aberrations, particularly in WL (by 26% in WL). Our results suggest that the systematic decrease in visual performance with visual acuity and retinal image quality by simulation with convolved stimuli appears to be primarily associated with a lack of favorable interaction between chromatic and monochromatic aberrations in the eye.

Purpose : Image convolutions are often used to simulate the effects of ocular aberrations on image quality.We studied potential discrepancies in the image degradation/visual performance using convolved images(viewed through corrected optics)or the real aberrations,in both monochromatic & white light(WL)

Light is an element that draws together many areas of human knowledge: physics, chemistry, biology, astronomy, engineering, and art. Moreover, optical phenomena and the technologies based on them are widespread in our daily lives. However, it can be difficult to understand or explain these phenomena. What is light? Where are optics and photonics present in our lives and in nature? What lies behind different optical phenomena? What is an optical instrument? How does the eye resemble an optical instrument? How can we explain human vision? This book, written by a group of young scientists, answers these questions and many more to help you to get to know the exciting world of optics and photonics. It is intended for the general public, with an emphasis on students at all levels of secondary education. A variety of easy-to-follow experiments related to different optical phenomena and technologies are presented. All of them are preceded by an explanation of the concepts and accompanied by numerous illustrations and curiosities. All of it is meant for you to have fun with optics and photonics!

Visual simulators are useful tools to provide patients experience of multifocal vision prior to treatment. In this study, commercially available center-near aspheric multifocal contact lenses (MCLs) of low, medium, and high additions were mapped on a spatial light modulator (SLM) and validated on a bench. Through focus visual acuity (TFVA) was measured in subjects through the SLM and real MCLs on the eye. A correlation metric revealed statistically significant shape similarity between TFVA curves with real and simulated MCLs. A Bland-Altman analysis showed differences within confidence intervals of ±0.01 logMAR for LowAdd/MediumAdd and ±0.06 logMAR for HighAdd. Visual performance with simulated MCLs outperformed real MCLs by ∼20%. In conclusion, SLM captures the profile of center-near MCLs and reproduces vision with real MCLs, revealing that the MCL profile and its interactions with the eye’s optics (and not fitting aspects) account for the majority of the contributions to visual performance with MCLs

Visual simulators aim at evaluating vision with ophthalmic corrections prior to prescription or implantation of intraocular lenses (IOLs) in the patient’s eye. In the present study, we present the design, implementation, and validation of a new IOL-in-cuvette channel in an Adaptive Optics visual simulator, which provides an alternative channel for pre-operative simulation of vision with IOLs. The IOL is projected on the pupil’s plane of the subject by using a Rassow system. A second lens, the Rassow lens, compensates for an IOL of 20 D while other powers can be corrected with a Badal system within a 5 D range. The new channel was evaluated by through-focus (TF) optical quality in an artificial eye on bench, and by TF visual acuity in patients, with various IOL designs (monofocal, diffractive trifocal, and refractive extended depth of focus).

We have measured the ocular transverse chromatic aberration (TCA) in 11 subjects using 2D-two-color Vernier alignment, for two pupil diameters, in a polychromatic adaptive optics (AO) system. TCA measurements were performed for two pupil diameters: for a small pupil (2-mm), referred to as 'optical TCA' (oTCA), and for a large pupil (6-mm), referred to 'perceived TCA' (pTCA). Also, the TCA was measured through both natural aberrations (HOAs) and AO-corrected aberrations. Computer simulations of pTCA incorporated longitudinal chromatic aberration (LCA), the patient's HOAs measured with Hartmann-Shack, and the Stiles-Crawford effect (SCE), measured objectively by laser ray tracing. The oTCA and the simulated pTCA (no aberrations) were shifted nasally 1.20 arcmin and 1.40 arcmin respectively. The experimental pTCA (-0.27 arcmin horizontally and -0.62 vertically) was well predicted (81%) by simulations when both the individual HOAs and SCE were considered. Both HOAs and SCE interact with oTCA, reducing it in magnitude and changing its orientation. The results indicate that estimations of polychromatic image quality should incorporate patient's specific data of HOAs, LCA, TCA & SCE.

PURPOSE: To measure the in vivo longitudinal chromatic aberration (LCA) from the chromatic difference of focus (480 to 700 nm) using psychophysical methods in patients bilaterally implanted with a hydrophobic trifocal intraocular lens (IOL). METHODS: Psychophysical best focus was measured in both eyes at different wavelengths (480 to 700 nm) and at three different viewing distances (0.00, +1.75, and +3.50 diopters [D]) using a custom-developed polychromatic adaptive optics set-up provided with a supercontinuum laser, a Hartmann-Shack wavefront sensor, a deformable mirror, a motorized Badal system, a pupil monitoring system, and a psychophysical channel with monochromatically illuminated stimuli. Measurements were performed on 10 patients (20 eyes) bilaterally implanted with hydrophobic trifocal diffractive IOLs (FineVisionHP POD F GF; PhysIOL). LCA was computed from the chromatic difference of focus curves as the difference between 480 and 700 nm at near, intermediate, and far. RESULTS: The LCA from psychophysical measurements was significantly higher for far vision (0.99 ± 0.06 diopters [D]), than for intermediate (0.67 ± 0.10 D) and near (0.23 ± 0.08 D) vision (one-way analysis of variance, P < .05). CONCLUSIONS: LCA for far vision was significantly higher than for intermediate and near vision in hydrophobic trifocal diffractive IOLs, in agreement with a previous study with the same optical design but hydrophilic material IOLs. The LCA for the hydrophobic IOL is slightly higher than for the hydrophilic IOL at far. Different combinations of refractive and diffractive LCA will allow optimizing IOL designs to improve polychromatic image quality.

Purpose: Adaptive Optics allows measurement and manipulation of the optical aberrations of the eye. We review two Adaptive Optics set-ups implemented at the Visual Optics and Biophotonics Laboratory, and present examples of their use in better understanding of the role of optical aberrations on visual perception, in normal and treated eyes. Recent findings: Two systems (AOI and AOII) are described that measure ocular aberrations with a Hartmann-Shack wavefront sensor, which operates in closed-loop with an electromagnetic deformable mirror, and visual stimuli are projected in a visual display for psychophysical measurements. AOI operates in infrared radiation (IR) light. AOII is provided with a supercontiniuum laser source (IR and visible wavelengths), additional elements for simulation (spatial light modulator, temporal multiplexing with optotunable lenses, phase plates, cuvette for intraocular lenses-IOLs), and a double-pass retinal camera. We review several studies undertaken with these AO systems, including the evaluation of the visual benefits of AO correction, vision with simulated multifocal IOLs (MIOLs), optical aberrations in pseudophakic eyes, chromatic aberrations and their visual impact, and neural adaptation to ocular aberrations. Summary: Monochromatic and chromatic aberrations have been measured in normal and treated eyes. AO systems have allowed understanding the visual benefit of correcting aberrations in normal eyes and the adaptation of the visual system to the eye's native aberrations. Ocular corrections such as intraocular and contact lenses modify the wave aberrations. AO systems allow simulating vision with these corrections before they are implanted/fitted in the eye, or even before they are manufactured, revealing great potential for industry and the clinical practice. This review paper is part of a special issue of Ophthalmic & Physiological Optics on women in visual optics, and is co-authored by all women scientists of the research team.

While multifocal intraocular lenses (MIOLs) are increasingly implanted to correct for presbyopia, how one sees with a multifocal correction is hard to explain and imagine. The current study evaluates the quality of various visual simulating technologies by comparing vision with simulated MIOLs pre-operatively and the implanted MIOLs post-operatively in the same patients. Two simulation platforms were used: (1) a custom-developed adaptiveoptics (AO) system, with two visual simulator devices: a spatial light modulator (SLM) and an optotunable lens operating under temporal multiplexing (SimVis); and (2) a wearable, binocular, large field of view SimVis2Eyes clinical simulator (SimVis Gekko, 2Eyes Vision, Madrid, Spain). All devices were programmed to simulate a trifocal diffractive MIOL (POD F, FineVision, PhysIOL). Eight patients were measured pre-operatively simulating the trifocal lens and post-operatively with implantation of the same MIOL. Through-focus decimal visual acuity (TF VA) was measured (1) monocularly in monochromatic light using a four-alternative-forced-choice procedure in the AO system; and (2) binocularly using a clinical optotype in white light. Visual simulations pre-operatively predict well the TF VA performance found post-operatively in patients implanted with the real IOL. The average RMS difference between TF curves with the different visual simulators was 0.05 ± 0.01. The average RMS difference between the TF VA curves with the SimVis pre-operatively and the real MIOL post-operatively was 0.06 ± 0.01 in both platforms, and it was higher in cataract eyes (0.08 ± 0.01, on average across simulators) than in eyes with clear lens. In either group the shape of the TF curves is similar across simulators and pre- and post-operatively. TF curves cross-correlated significantly between simulators (lag k = 0, rho = 0.889), as well as with results with the real MIOL implanted (lag k = 0, rho = 0.853). Visual simulations are useful programmable tools to pre

Adaptive optics (AO) visual simulators based on deformable mirrors, spatial light modulators or optotunable lenses are increasingly used to simulate vision through different multifocal lens designs. However, the correspondence of this simulation with that obtained through real intraocular lenses (IOLs) tested on the same eyes has not been, to our knowledge, demonstrated. We compare through-focus (TF) optical and visual quality produced by real multifocal IOLs (M-IOLs) -bifocal refractive and trifocal diffractive- projected on the subiect’s eye with those same designs simulated with a spatial light modulator (SLM) or an optotunable lens working in temporal multiplexing mode (SimVis technology). Measurements were performed on 7 cyclopleged subjects using a custom-made multichannel 3-active-optical-elements polychromatic AO Visual Simulator in monochromatic light. The same system was used to demonstrate performance of the real IOLs, SLM and SimVis technology simulations on bench using double-pass imaging on an artificial eye. Results show a general good correspondence between the TF performance with the real and simulated M-IOLs, both optically (on bench) and visually (measured visual acuity in patients). We demonstrate that visual simulations in an AO environment capture to a large extent the individual optical and visual performance obtained with real M-IOLs, both in absolute values and in the shape of through-focus curves.