Implantation of a diffractive trifocal intraocular lens: One-year follow-up

Purpose: To evaluate the visual, refractive, contrast-sensitivity, and aberrometric outcomes during a 1-year follow-up after implantation of a trifocal intraocular lens (IOL). Setting: Premium Clinic, Teplice, Czech Republic. Design: Prospective case series. Methods: This study included eyes of patients having cataract surgery with implantation of the trifocal IOL model AT Lisa tri 839MP. Distance, intermediate (66 and 80 cm), and near (33 and 40 cm) vision; contrast sensitivity; aberrometric outcomes; and the defocus curve were evaluated during a 12-month follow-up. The level of posterior capsule opacification (PCO) was also evaluated. Results: In 120 eyes (60 patients), 1 month postoperatively, an improvement was observed in all visual parameters (P ≤ .03) except corrected near and intermediate visual acuities (both P ≥ .05). From 1 month to 12 months postoperatively, small but statistically significant changes were observed in uncorrected and corrected distance and near visual acuities (all P ≤ .03) and in uncorrected intermediate visual acuity (P = .01). In the defocus curve, no significant differences were found between visual acuities corresponding to defocus levels of −1.0 diopter (D) and −2.0 D (P = .22). The level of ocular spherical aberration decreased statistically significantly at 6 months (P < .001). Ocular and internal higher-order aberrations increased minimally but significantly from 6 to 12 months postoperatively (P < .001). The mean 12-month PCO score was 0.32 ± 0.44 (SD). Four eyes (3.3%) required neodymium:YAG capsulotomy. Conclusion: The trifocal IOL provided complete and stable visual restoration after cataract surgery during a 12-month follow-up, with good levels of visual quality.

Management of subluxated cataract with capsule anchor implantation

We describe a small case series that provides preliminary evidence of the usefulness of a new capsule-anchoring device for the management of subluxated cataracts. Three eyes of 3 patients with traumatic subluxated cataract causing a significant visual loss were enrolled. Phacoemulsification was performed in all cases with implantation of a capsule-anchoring device (AssiAnchor) because partial zonular dehiscence was present. A significant visual improvement was achieved in the 3 cases. The capsular bag was well centered and the anchors firmly attached to the capsulorhexis and sclera at 12 months postoperatively. The capsule-anchoring device was helpful in managing traumatic subluxated cataracts, enabling effective centration of the intraocular lens–capsular bag complex and, consequently, effective visual restoration.

Clinical Characterization of Asymptomatic or Minimally Symptomatic Young Patients Showing Signs Compatible With Dry Eye: A Pilot Study

Purpose: To evaluate and characterize the clinical profile of young asymptomatic or minimally symptomatic patients without diagnosis of dry eye but showing signs compatible with dry eye syndrome (DES). Methods: Prospective study including a total of 50 consecutive subjects with ages ranging from 18 to 40 years that were identified as asymptomatic or minimally symptomatic by means of the Ocular Surface Disease Index (OSDI) (score of <22). In all patients, a complete battery of tests for the diagnosis of DES was performed including the evaluation of the tear film break-up time (TFBUT), the level of corneal and conjunctival staining, and the eyelid and Meibomian morphology. Results: The OSDI score was significantly higher in women than in men (median: 12.5 vs. 5.3, P=0.01). Low grades of ocular surface staining, dysfunction of Meibomian gland expression, and alteration of quality of Meibomian secretions were observed in 56%, 58%, and 84% of eyes, respectively. More eyes with some dysfunction of Meibomian gland expressibility had a TFBUT less than 5 sec (P=0.033). A statistically significant difference in the OSDI score was found between patients with and without systemic allergies (P=0.036) and between male and female (P=0.01). Likewise, the OSDI score was significantly higher in those women wearing contact lenses compared with those not wearing them (P=0.012). Conclusions: Asymptomatic or minimally symptomatic young subjects may present low grades of clinical signs compatible with DES, with a trend to more symptomatology in women and allergic patients. These outcomes should be confirmed in future studies with larger samples.

Wavefront-Guided Laser Treatment Using a High-Resolution Aberrometer to Measure Irregular Corneas: A Pilot Study

PURPOSE: To evaluate in a pilot study the visual, refractive, corneal topographic, and aberrometric changes after wavefront-guided LASIK or photorefractive keratectomy (PRK) using a high-resolution aberrometer to calculate the treatment for aberrated eyes. METHODS: Twenty aberrated eyes of 18 patients undergoing wavefront-guided LASIK or PRK using the VISX STARS4IR excimer laser and the iDesign aberrometer (Abbott Medical Optics, Inc., Santa Ana, CA) were enrolled in this prospective study. Three groups were differentiated: keratoconus post-CXL group including 11 keratoconic eyes (10 patients), post-LASIK group including 5 eyes (5 patients) with previous decentered LASIK treatments, and post-RK group including 4 eyes (3 patients) with previous radial keratotomy. Visual, refractive, contrast sensitivity, corneal topographic, and ocular aberrometric changes were evaluated during a 6-month follow-up. RESULTS: An improvement in uncorrected (UDVA) and corrected visual acuity (CDVA) associated with a reduction in the spherical equivalent was observed in the three groups, but was only statistically significant in the keratoconus post-CXL and post-LASIK groups (P ≤ .04). All eyes gained one or more lines of CDVA after surgery. Improvements in contrast sensitivity were observed in the three groups, but they were only statistically significant in the keratoconus post-CXL and post-LASIK groups (P ≤ .04). Regarding aberrations, a reduction was observed in trefoil aberrations in the keratoconus post-CXL group (P = .05) and significant reductions in higher-order and primary coma aberrations in the post-LASIK group (P = .04). CONCLUSIONS: Wavefront-guided laser enhancements using the evaluated platform seem to be safe and effective to restore the visual function in aberrated eyes.

Methods and algorithms for video-based multi-point frequency measuring and mapping

Software for video-based multi-point frequency measuring and mapping: http://hdl.handle.net/10045/53429

Software for "Realistic limits for subpixel movement detection"

Object tracking with subpixel accuracy is of fundamental importance in many fields since it provides optimal performance at relatively low-cost. Although there are many theoretical proposals that lead to resolution increments of several orders of magnitude, in practice, this resolution is limited by the imaging systems. In this paper we propose and demonstrate through numerical models a realistic limit for subpixel accuracy. The final result is that maximum achievable resolution enhancement is connected with the dynamic range of the image, i.e. the detection limit is 1/2^(nr.bits). Results here presented may help to proper design of superresolution experiments in microscopy, surveillance, defense and other fields.

A conceptual map about alternating current circuits

Teachers are deeply concerned on how to be more effective in our task of teaching. We must organize the contents of our specific area providing them with a logical configuration, for which we must know the mental structure of the students that we have in the classroom. We must shape this mental structure, in a progressive manner, so that they can assimilate the contents that we are trying to transfer, to make the learning as meaningful as possible. In the generative learning model, the links before the stimulus delivered by the teacher and the information stored in the mind of the learner requires an important effort by the student, who should build new conceptual meanings. That effort, which is extremely necessary for a good learning, sometimes is the missing ingredient so that the teaching-learning process can be properly assimilated. In electrical circuits, which we know are perfectly controlled and described by Ohm's law and Kirchhoff's two rules, there are two concepts that correspond to the following physical quantities: voltage and electrical resistance. These two concepts are integrated and linked when the concept of current is presented. This concept is not subordinated to the previous ones, it has the same degree of inclusiveness and gives rise to substantial relations between the three concepts, materializing it into a law: The Ohm, which allows us to relate and to calculate any of the three physical magnitudes, two of them known. The alternate current, in which both the voltage and the current are reversed dozens of times per second, plays an important role in many aspects of our modern life, because it is universally used. Its main feature is that its maximum voltage is easily modifiable through the use of transformers, which greatly facilitates its transfer with very few losses. In this paper, we present a conceptual map so that it is used as a new tool to analyze in a logical manner the underlying structure in the alternate current circuits, with the objective of providing the students from Sciences and Engineering majors with another option to try, amongst all, to achieve a significant learning of this important part of physics.

Guía para el profesor novel (v 1.0)

El título de este trabajo sugiere que su texto fue preparado para que pudiera servir de ayuda al profesor novel. De hecho puede ser útil a quien quiera que se dedique a la profesión docente. El fenómeno fundamental que tiene lugar en las aulas es la adquisición de conocimientos por parte del alumno. El verbo que denota esta actividad se representa con la palabra aprender. La contribución del profesor consiste en conseguir que se aprenda de una forma selectiva, con “gusto” y eficacia. Se han de aprender unas cosas y no otras, se ha disfrutar de lo que se hace y no se ha de perder tiempo. Aunque la única actividad realmente importante es el aprender de los alumnos, los que hablan del asunto, que son los que saben hablar, como profesores, pedagogos, administradores y políticos, casi siempre han examinado el proceso desde su óptica y la denominan enseñar. Así, al proceso que tiene lugar lo llaman enseñanza. Este punto de vista es tan acentuado que ni siquiera existe la palabra aprendanza y ya va siendo hora que alguien la invente. La palabra aprendizaje se usa cuando lo que se aprende es una acción como leer, escribir, correr, nadar, etc. En este trabajo el lector puede encontrar 70 consejos que pueden servir de ayuda al novel profesor en su labor de dirigir la aprendanza de sus alumnos, contando con un bagaje algo más amplio que la simple intuición. En el ejercicio de la docencia todos nos hemos encontrado en situaciones apuradas. Para salir de ellas hemos tenido que optar por utilizar métodos más allá del dominio de la materia. En este trabajo se ofrecen algunos ejemplos de estos métodos que pueden ser utilizados con ventaja. Hay más. Confío que figurarán en sucesivas ediciones. Cada lector tendrá que decidir cuales son los más adecuados a su situación. A lo largo de los 70 consejos existe un talante inspirador. Algo así como si los autores siguieran un meta-consejo que les guíara y se reflejara en todas partes, sin deletrearse en ninguna. Me voy a tomar la libertad de hacerlo yo, sin su permiso. Consejo 0.1 Enamórate de tu profesión. Es preciosa. No hay espectáculo más fabuloso que ver como la mente de un alumno se va abriendo como una flor en primavera y es una gozada saberse parte del proceso. José Miró Nicolau Palma de Mallorca, Junio de 2005.

Realistic limits for subpixel movement detection

Object tracking with subpixel accuracy is of fundamental importance in many fields since it provides optimal performance at relatively low cost. Although there are many theoretical proposals that lead to resolution increments of several orders of magnitude, in practice this resolution is limited by the imaging systems. In this paper we propose and demonstrate through simple numerical models a realistic limit for subpixel accuracy. The final result is that maximum achievable resolution enhancement is connected with the dynamic range of the image, i.e., the detection limit is 1/2∧(nr.bits). The results here presented may aid in proper design of superresolution experiments in microscopy, surveillance, defense, and other fields.

Iluminando a las investigadoras en el Año Internacional de la Luz

El año 2015 fue declarado por las Naciones Unidas como el Año Internacional de la Luz y de las Tecnologías basadas en la luz. Varias personas pertenecientes al Grupo Especializado de Mujeres en Física de la Real Sociedad Española de Física (RSEF) y a la Sociedad Española de Óptica (SEDOPTICA) nos organizamos para llevar a cabo distintas actividades con objeto de visibilizar a algunas investigadoras que han realizado su labor científica en estos campos y cuyas contribuciones son poco o nada conocidas. Animadas por dos de los objetivos de la declaración del año 2015 como el Año Internacional de la Luz y de las Tecnologías basadas en la Luz, a saber: “promocionar el empoderamiento de la mujer en la Ciencia” y “fomentar vocaciones científicas en el ámbito de la luz y de sus aplicaciones”, surgió nuestra motivación. Indudablemente dando visibilidad a la labor de estas científicas y valorando sus aportaciones en el avance de las tecnologías ópticas y fotónicas de nuestra sociedad crearemos referentes para las futuras generaciones y, sobre todo, para las jóvenes estudiantes, contribuyendo a la consecución de la igualdad efectiva entre mujeres y hombres.

Profitability analysis of a femtosecond laser system for cataract surgery using a fuzzy logic approach

AIM: To define the financial and management conditions required to introduce a femtosecond laser system for cataract surgery in a clinic using a fuzzy logic approach. METHODS: In the simulation performed in the current study, the costs associated to the acquisition and use of a commercially available femtosecond laser platform for cataract surgery (VICTUS, TECHNOLAS Perfect Vision GmbH, Bausch & Lomb, Munich, Germany) during a period of 5y were considered. A sensitivity analysis was performed considering such costs and the countable amortization of the system during this 5y period. Furthermore, a fuzzy logic analysis was used to obtain an estimation of the money income associated to each femtosecond laser-assisted cataract surgery (G). RESULTS: According to the sensitivity analysis, the femtosecond laser system under evaluation can be profitable if 1400 cataract surgeries are performed per year and if each surgery can be invoiced more than $500. In contrast, the fuzzy logic analysis confirmed that the patient had to pay more per surgery, between $661.8 and $667.4 per surgery, without considering the cost of the intraocular lens (IOL). CONCLUSION: A profitability of femtosecond laser systems for cataract surgery can be obtained after a detailed financial analysis, especially in those centers with large volumes of patients. The cost of the surgery for patients should be adapted to the real flow of patients with the ability of paying a reasonable range of cost.

Simulación de un enlace óptico WDM (Wavelength Division Multiplexing) utilizando POFs (Polymer Optical Fiber) en el espectro de luz visible

En este proyecto se analizaron las características y el modo de operación de las fibras ópticas plásticas en un enlace óptico WDM (Wavelenght Division Multiplexing) operando en el espectro visible. Se estudiaron los componentes activos y pasivos necesarios para el enlace, como son las fuentes LED, multiplexores, filtros y acopladores. Se analizaron los efectos no lineales que se pueden presentar en la fibra óptica, y que son importantes de considerar al transmitir señales WDM. Para respaldar el análisis se simuló en MATLAB un enlace óptico en el dominio de la frecuencia utilizando fuentes LED que emiten en el espectro visible, junto con multiplexores WDM, filtros de absorción, acopladores y como medio de transmisión la Fibra Óptica Plástica (POF -Plastic Optical Fiber).

Estudio de evolución microestructural de una superaleación base Ni-Cr-Mo bajo diferentes condiciones termomecánicas

El presente trabajo de investigación tuvo como objetivo principal, el determinar y caracterizar la microestructura de una superaleación Inconel 625 antes y después de pasar por procesos termomecánicos, con el fin de comprender su evolución microestructural y sus fases presentes. Para cumplir este objetivo se propuso realizar una caracterización microestructural antes y después de una serie de trabajos termomecánicos, los cuales se realizaron ensayos mecánicos de compresión en caliente a diferentes temperaturas (900ºC, 950°C, 1000°C, 1050°C) a diferentes velocidades de deformación (0.1 mm/s, 0.01 mm/s), en muestras previamente solubilizadas a 1150°C por 1 hora. Esto con la finalidad de caracterizar el material bajo estas condiciones termomecánicas, esto con el fin de observar la formación de fases y precipitación de carburos, todo esto mediante el uso de técnicas como Difracción de Rayos X, Análisis Térmico, Microscopia Óptica, y Microscopia Electrónica de Barrido.

Measurement of the magnetic field of small magnets with a smartphone: a very economical laboratory practice for introductory physics courses

In this work, we propose an inexpensive laboratory practice for an introductory physics course laboratory for any grade of science and engineering study. This practice was very well received by our students, where a smartphone (iOS, Android, or Windows) is used together with mini magnets (similar to those used on refrigerator doors), a 20 cm long school rule, a paper, and a free application (app) that needs to be downloaded and installed that measures magnetic fields using the smartphone's magnetic field sensor or magnetometer. The apps we have used are: Magnetometer (iOS), Magnetometer Metal Detector, and Physics Toolbox Magnetometer (Android). Nothing else is needed. Cost of this practice: free. The main purpose of the practice is that students determine the dependence of the component x of the magnetic field produced by different magnets (including ring magnets and sphere magnets). We obtained that the dependency of the magnetic field with the distance is of the form x-3, in total agreement with the theoretical analysis. The secondary objective is to apply the technique of least squares fit to obtain this exponent and the magnetic moment of the magnets, with the corresponding absolute error.

Single-Polarization Double Refraction in Plasmonic Crystals: Considerations on Energy Flow

We examined the optical properties of nanolayered metal-dielectric lattices. At subwavelength regimes, the periodic array of metallic nanofilms demonstrates nonlocality-induced double refraction, conventional positive and as well as negative. In particular, we report on energy-flow considerations concerning both refractive behaviors concurrently. Numerical simulations provide transmittance of individual beams in Ag-TiO2 metamaterials under different configurations. In regimes of the effective-medium theory predicting elliptic dispersion, negative refraction may be stronger than the expected positive refraction.