Influencia de los diferentes tipos de astigmatismo en la agudeza visual

[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.Remón Martín, L.; Monsoriu Serra, JA.; Furlan, WD. (2017). Influence of different types of astigmatism on visual acuity. Journal of Optometry. 10(3):141-148. https://doi.org/10.1016/j.optom.2016.07.003S14114810

Diseño y desarrollo de un espectrómetro óptico versátil de bajo coste

[EN] In this work, the processes of designing, developing and prototyping an instrument to measure the visible spectrum is shown in detail. The objective is to obtain a low-cost device, reproducible and technically competitive with the commercial docent models. The obtained device is portable, adaptable, compact, economic and with high connectivity. The core of the project is the software, and its key point is the compatibility with any commercial camera and it can be run in different operative systems. For this prototype a commercial camera with USB connection has been considered in order to find a balance between price and resolution for the resulting device.[ES] En este trabajo se detalla el proceso de diseño, desarrollo y prototipado de un sistema de medida del espectro visible. El objetivo que hay que cumplir es la obtención de un dispositivo reproducible, competitivo en el aspecto técnico con modelos comerciales de docencia actuales, y económico. El dispositivo resultante reúne las características de ser portátil, versátil, compacto, económico y con alta conectividad. El centro del proyecto es el software, que como característica clave permite ser utilizado prácticamente con cualquier cámara comercial y ser ejecutado desde distintos sistemas operativos. El prototipado se ha realizado con una cámara comercial con conexión USB con el fin de encontrar un equilibrio entre asequibilidad y resolución del producto final. Tiene un precio 20 veces más económico y una resolución similar al espectrofotómetro comercial utilizado como referencia.Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad y FEDER (Proyecto DPI2015-71256-R) y por la Generalitat Valenciana (Proyecto PROMETEOII-2014-072).Ferrando, V.; Monreal, J.; Furlan, WD.; Monsoriu Serra, JA. (2017). Diseño y desarrollo de un espectrómetro óptico versátil de bajo coste. Tecnica Industrial. (318):48-52. https://doi.org/10.23800/9984S485231

Coléteres foliares de Oxypetalum R. Br. (Asclepiadoideae, Apocynaceae) — Aspectos ultraestruturais e anatômicos úteis à taxonomia das espécies do Paraná (Brasil)

Coléteres foliares de Oxypetalum R. Br. (Asclepiadoideae, Apocynaceae) — Aspectos ultraestruturais e anatômicos úteis à taxonomia das espécies do Paraná (Brasil) </htm

Terahertz Sieves

[EN] Imaging at terahertz (THz) frequencies offers a great potential for applications including security screening, telecommunications biodetection, and spectroscopy. Some of these applications need specially designed lenses with customized characteristics that are not commercially available. In this letter, we present the THz sieves as a new kind of THz lenses. We demonstrate that these lenses improve the resolution of conventional zone plates constructed with the same level of detail. Amplitude and phase THz sieves were three-dimensional printed and tested experimentally. Excellent agreement was obtained between the experimental and calculated results.This work was supported in part by the Ministerio de Economia y Competitividad and FEDER, Spain, under Grant DPI2015-71256-R, in part by the Generalitat Valenciana under Grant PROMETEOII-2014-072, Spain, and in part by the National Center for Research and Development in Poland under Grant LIDER/020/319/L-5/13/NCBR/2014.Machado-Olivares, FJ.; Zagrajek, P.; Monsoriu Serra, JA.; Furlan, WD. (2018). Terahertz Sieves. IEEE Transactions on Terahertz Science and Technology. 8(1):140-143. https://doi.org/10.1109/TTHZ.2017.2762292S1401438

Visual acuity and contrast sensitivity screening with a new iPad application

We present a new iPad application (app) for a fast assessment of Visual Acuity (VA) and Contrast Sensitivity (CS) whose reliability and agreement was evaluated versus a commercial screening device (Optec 6500). The measurement of VA was programmed in the app in accordance with the Amblyopia Treatment Study protocol. The CS was measured with sinusoidal gratings of four different spatial frequencies: 3, 6, 12 and 18 cpd at the same contrast values of the Functional Acuity Contrast Test (FACT) included in the Optec 6500. Forty-five healthy subjects with monocular corrected visual acuities better than 0.2 logMAR participated in the agreement study. Bland-Altman analyses were performed to assess the agreement and Deming regressions to calculate Mean Differences (MDs) and Limits of Agreement (LoAs). Coefficients of reliability were 0.15 logMAR for our method and 0.17 logMAR for the ETDRS testing protocol. For testing the CS, our test showed no statistically significant differences compared with the FACT at any spatial frequency (p > 0.05). The MDs were lower than 0.05 log units for all spatial frequencies.This work was funded by 'Ministerio de Economia y Competitividad' - 'Spain' (Grants FIS2011-23175 and DPI2015-71256-R) and 'Generalitat Valenciana' - 'Spain' (Grants PROMETEOII/2014/072 and ACOMP/2014/180).Rodríguez-Vallejo, M.; Llorens Quintana, C.; Furlan, WD.; Monsoriu Serra, JA. (2016). Visual acuity and contrast sensitivity screening with a new iPad application. Displays. 44:15-20. https://doi.org/10.1016/j.displa.2016.06.001S15204

Stereopsis assessment at multiple distances with an iPad application

[EN] We present a new application for iPad for screening stereopsis at multiple distances that allows testing up to ten levels of stereoacuity at each distance. Our approach is based on a random dot stereogram viewable with anaglyph spectacles. Sixty-five subjects with no ocular diseases, wearing their habitual correction were measured at 3 m and 0.5 m. Results were compared with a standard stereoscopic test (TNO). We found not statistically significant differences between both tests, but our method achieved higher reproducibility. Applications in visual screening programs and to design and use of 3D displays, are suggested. (C) 2017 Elsevier B.V. All rights reserved.This work was supported by the Ministerio de Economia y Competitividad and FEDER (Grant DPI2015-71256-R) and by the Generalitat Valenciana (Grant PROMETEOII-2014-072), Spain. D. Montagud acknowledges financial support from Universitat Politecnica de Valencia (PAID-01-16)Rodríguez-Vallejo, M.; Ferrando, V.; Montagud-Martínez, D.; Monsoriu Serra, JA.; Furlan, WD. (2017). Stereopsis assessment at multiple distances with an iPad application. Displays. 50:35-40. https://doi.org/10.1016/j.displa.2017.09.001S35405

cDNA-AFLP analysis of Psidium guajava L. cultivars under water stress and mechanical injury: methodological implications

Studies involving amplified fragment length polymorphism (cDNA-AFLP) have often used polyacrylamide gels with radiolabeled primers in order to establish best primer combinations, to analyze, and to recover transcript-derived fragments. Use of automatic sequencer to establish best primer combinations is convenient, because it saves time, reduces costs and risks of contamination with radioactive material and acrylamide, and allows objective band-matching and more precise evaluation of transcript-derived fragments intensities. This study aimed at examining the gene expression of commercial cultivars of P. guajava subjected to water and mechanical injury stresses, combining analyses by automatic sequencer and fluorescent kits for polyacrylamide gel electrophoresis. Firstly, 64 combinations of EcoRI and MseI primers were tested. Ten combinations with higher number of polymorphic fragments were then selected for transcript-derived fragments recovering and cluster analysis, involving 45 saplings of P. guajava. Two groups were obtained, one composed by the control samplings, and another formed by samplings undergoing stress, with no clear distinction between stress treatments. The results revealed the convenience of using a combination of automatic sequencer and fluorescent kits for polyacrylamide gel electrophoreses to examine gene expression profiles. The Unweighted Pair Group Method with Arithmetic Mean analysis using Euclidean distances points out a similar induced response mechanism of P. guajava undergoing water stress and mechanical injury