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We present a different approach to the teaching of optics in primary and secondary school which focuses on the development of hands-on experiments, enabling young students to have a closer look to optics and photonics.

The purpose of this study was to assess the impact of different intracorneal ring segments (ICRS) combinations on corneal morphology and visual performance on patients with keratoconus.

Durante el crecimiento del ojo existe un acople entre las potencias de la córnea y cristalino y la longitud axial, es decir, la distancia focal se va ajustando para proporcionar la mejor calidad óptica. Sin embargo, hay ocasiones en las que este mecanismo de acople falla y se desarrolla un error refractivo, siendo la miopía uno de los errores de refracción más comunes. A pesar de su alta prevalencia, todavía desconocemos las razones de la miopía. Estudios recientes han asociado los cambios axiales en pacientes miopes con cambios estructurales en la zona anterior de la esclera y en la córnea periférica; pero los resultados descritos no se han mostrado concluyentes y a día de hoy desconocemos el papel que desempeña la córnea, principal elemento refractivo del ojo, en la progresión de la miopía. En el presente Trabajo de Fin de Grado se ha desarrollado un modelo multicapa de córnea, utilizando herramientas matemáticas y de diseño óptico, con el fin último de estudiar el impacto de la córnea en el desarrollo de la miopía. Los modelos se generaron con los datos morfológicos de la córnea y epitelio en la zona central y periférica utilizando los datos experimentales de distintas publicaciones científicas y de dos pacientes con miopía magna. Los resultados obtenidos muestran que el impacto de los cambios geométricos y estructurales de la córnea sobre el error refractivo son mínimos (menor de 0.1 dioptría) y su contribución se considera residual en desarrollo de la miopía., During ocular growth the eye balances optical changes with its increasing axial length to ultimately achieve emmetropia. However, in the presence of degraded image quality this tuning mechanism fails and the eye continuous to grow in the axial dimension, resulting in myopia. Despite high prevalence and much research, the mechanisms underlying the development of myopia are unknown. Recent studies indicate that the changes in the anterior sclera and corneal periphery are associated with an axial modification in increasing levels of myopia; but these changes were not conclusive and, to date, the potential role of the cornea in myopia development is not fully understood. In this study, a multilayer corneal model based on morphological data from the literature was develop to study the impact of the cornea in the development of myopia. The models were also generated with real data measured in two high-myope patients. The results show that the impact of the geometrical and structural changes of the cornea on the refractive error are minimal (less than 0.1 diopters) and their contribution could be considered residual in the development of myopia., Departamento de Biología Celular, Histología y Farmacología, Grado en Óptica y Optometría

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!

La córnea es el principal elemento refractivo del ojo, por lo que conocer en detalle la función de sus capas como estructura biológica y sistema óptico es de crucial importancia para clasificar patologías corneales o planificar cualquier acción refractiva sobre sus superficies, ya sea por medio de la adaptación de lentes de contacto o mediante cirugía refractiva corneal. En el presente trabajo se desarrollará un modelo teórico de córnea a partir de la selección de distintas plataformas de lentes de contacto que simulen las características de las capas del epitelio, estroma y endotelio. Los valores nominales de las lentes seleccionadas se incluirán en un programa de diseño óptico de trazado de rayos para analizar la potencia de la córnea y relacionar las características de asfericidad con aberración esférica. Además, se compararán los resultados obtenidos con los analizados con los valores promedio de la córnea., The majority of the refractive power of the eye is provided by the cornea, therefore understanding the link between the biological functions of the different layers and the optical properties of its structure is key for comprehending how the cornea works, and will be essential to classify corneal pathologies and design corneal refractive strategies with contact lenses and corneal surgery. In this study, we will design different theoretical multilayer model corneas using the nominal values of the contact lenses. We will select different platforms that mimic the biological and optical properties of the epithelium, stroma and endothelium. We will incorporate the selected lenses into an optical design software based on ray tracing to study the relationship between the geometrical and optical properties, in particular asphericity and spherical aberration. Furthermore, we will compare the results of the corneal models with the average data of a human cornea., Grado en Óptica y Optometría

Ocular biometric parameters, including full shape crystalline lens, were assessed in myopes and emmetropes using 3-D optical coherence tomography. The anterior chamber depth, the radius of the curvature of the anterior cornea, anterior lens, and posterior lens, lens thickness, lens equatorial diameter, surface area, equatorial position, volume, and power, were evaluated as functions of refractive errors and axial lengths while controlling for age effects. The crystalline lens appears to change with myopia consistent with lens thinning, equatorial, and capsular stretching while keeping constant volume. Axial elongation appears counteracted by a crystalline lens power reduction, while corneal power remains unaffected.

In a cataract surgery, the opacified crystalline lens is replaced by an artificial intraocular lens (IOL). To optimize the visual quality after surgery, the intraocular lens to be implanted must be selected preoperatively for every individual patient. Different generations of formulas have been proposed for selecting the intraocular lens dioptric power as a function of its estimated postoperative position. However, very few formulas include crystalline lens information, in most cases only one-dimensional. The present study proposes a new formula to preoperatively estimate the postoperative IOL position (ELP) based on information of the 3-dimensional full shape of the crystalline lens, obtained from quantitative eye anterior segment optical coherence tomography imaging. Real patients were measured before and after cataract surgery (IOL implantation). The IOL position and the postoperative refraction estimation errors were calculated by subtracting the preoperative estimations from the actual values measured after surgery. The proposed ELP formula produced lower estimation errors for both parameters-ELP and refraction-than the predictions obtained with standard state-of-the-art methods, and opens new avenues to the development of new generation IOL power calculation formulas that improve refractive and visual outcomes.

Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). The repeatability of the surface elevation was less than 2 µm. Surface astigmatism was the individual dominant term in all surfaces. Higher-order RMS surface elevation was largest in the posterior lens. Individual surface elevation Zernike terms correlated significantly across corneal and anterior lens surfaces. Higher-order-aberrations (except spherical aberration) were comparable with those predicted by OCT-based eye models.

PURPOSE: Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. METHODS: The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. RESULTS: Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction. CONCLUSIONS: Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality.

The full shape of the accommodating crystalline lens was estimated using custom three-dimensional (3-D) spectral OCT and image processing algorithms. Automatic segmentation and distortion correction were used to construct 3-D models of the lens region visible through the pupil. The lens peripheral region was estimated with a trained and validated parametric model. Nineteen young eyes were measured at 0-6 D accommodative demands in 1.5 D steps. Lens volume, surface area, diameter, and equatorial plane position were automatically quantified. Lens diameter & surface area correlated negatively and equatorial plane position positively with accommodation response. Lens volume remained constant and surface area decreased with accommodation, indicating that the lens material is incompressible and the capsular bag elastic.

PURPOSE. To compare corneal biomechanical properties after in vivo and ex vivo cross-linking (CXL) using rose bengal–green light (RGX) or riboflavin-UVA (UVX). METHODS. Corneas of 30 rabbits were treated in vivo by the two CXL modalities monolaterally (Group 1) or bilaterally (Group 2). Rabbits in Group 1 were euthanized 1 month after treatments and in Group 2 two months after treatment. Ex vivo CXL was also performed. Eyes were measured by Scheimpflug air puff corneal deformation imaging (Corvis ST) under constant IOP. Corneal deformation parameters were assessed. Inherent corneal biomechanical properties were estimated using inverse finite element modeling. RESULTS. Peak to peak distance decreased 16% 2 months after RGX, and 4% and 20% 1 and 2 months after UVX, respectively. The equivalent Young’s modulus (Eeq) increased relative to the control during the post treatment period for both RGX and UVX. The Eeq increased by factors of 3.4 (RGX) and 1.7 (UVX) 1 month and by factors of 10.7 (RGX) and 7.3 (UVX) 2 months after treatment. However, the Eeq values for ex vivo CXL were much greater than produced in vivo. The ex vivo Eeq was greater than the 1-month in vivo values by factors of 8.1 (RGX) and 9.1 (UVX) and compared with 2 month by factors of 2.5 (RGX) and 2.1 (UVX). CONCLUSIONS. These results indicate that corneal stiffness increases after CXL, and further increases as a function of time after both RGX and UVX. Also, while biomechanical properties determined after ex vivo CXL are indicative of corneal stiffening, they may not provide entirely accurate information about the responses to CXL in vivo.

To evaluate corneal wound healing after treatment with a new collagen crosslinking protocol using rose bengal dye and green light (RGX).