Impact of defocus in the measurement of light distortion: simulation and experimental measurements

Dissertação de mestrado em Optometria AvançadaCurrently it has been given more clinical relevance to visual disturbances that affect the performance of people in everyday activities, especially in low lighting conditions. In fact, vision quality is related with the resulting intraocular straylight from light scattering on optical means, the intrinsic aberrations of each subject and un-corrected refractive errors. All this can degrade the vision quality by perceiving dysphotopsias around light sources. There are several photic phenomena (like halos and starburst) associated to light distortion limiting the visual performance, especially in low luminance conditions, such as night driving. The association between intraocular light scattering and high-order aberration with visual quality and performance is well known and it is already taken into account in clinical practice for pathological situations, surgical and other visual treatments. It is known how defocus can influence the visual performance related to visual acuity, contrast sensitivity, reading and shapes and patterns recognition. However the increase on light distortion with defocus and its differences between myopes and hyperopes has not been yet studied. Therefore, it is relevant to study the impact of defocus in light distortion measures and how it is perceived, and any additional factors that may influence the visual quality along with the blur caused by non-corrected refractive errors as well, namely the action of accommodation, corneal surface regularity and symmetry and pupil size. In this cross-sectional study involving 20 healthy subjects the size and irregularity of light distortion surrounding a bright source of light against a dark background were evaluated with the Light Distortion Analyzer (LDA) under low luminance levels with positive and negative induced defocus of 1.00D, before and after the instillation of a cycloplegic drug. From this study we observed that there was a relevant increase on light distortion with both types of defocus (positive and negative) and both types of induced defocus produced similar values of light distortion in size and irregularity. The spherical-like HOA was the ocular aberration that most influenced light distortion measures, mainly its size, but the pupil by itself did not show to have a significant influence. Besides, the topographic indexes SRI and SAI showed to be predictors of visual quality by being positively related with light distortion size. The same it was not verified for the simulated PSF with the psychophysical measure from LDA in both positive and negative induced defocus. Given the results, we verified that despite the psychophysical capacity of the binocular system to attenuate the monocular effects, the importance and need to correct low refractive errors should not be dismissed, not only for a matter of improvement of visual acuity but also visual quality under dim light conditions.Atualmente a importância clínica dos distúrbios visuais que afetam a performance das pessoas em atividades do quotidiano, nomeadamente em condições de baixa iluminação, tem merecido relevo pela comunidade científica. De facto, a qualidade visual está relacionada com a dispersão da luz nos meios óticos, as aberrações oculares intrínsecas de cada sujeito e de erros refrativos não corrigidos. Tudo isto pode degradar a qualidade visual através da perceção distorcida de fenómenos luminosos (como halos e estrelas à volta das luzes) que limitam a performance visual dos sujeitos, nomeadamente em condições de baixa iluminação, como é o caso da condução noturna. A relação das aberrações oculares e da dispersão da luz intraocular com a qualidade e performance visual é já bem conhecida e tida em conta na prática clínica em situações patológicas, cirúrgicas e outros tratamentos. Sabe-se de que forma o desfocado pode influenciar a performance visual em termos de acuidade visual, sensibilidade ao contraste, velocidade de leitura, reconhecimento de formas e padrões. No entanto, não se conhece de que forma o desfocado aumenta a distorção luminosa e se difere ou não entre míopes e hipermétropes. Assim, torna-se relevante conhecer de que forma o desfocado tem impacto em medidas de distorção luminosa e como é percebida, bem como quais os fatores adicionais que poderão influenciar a qualidade visual juntamente com o desfocado provocado pela não correção de erros refrativos. Neste estudo transversal utilizou-se o Light Distortion Analyzer (LDA) para medidas do tamanho e irregularidade da distorção luminosa em situações de baixa iluminação aquando da simulação de desfocado positivo e negativo de 1,00D, após a atuação de um fármaco cicloplégico. Este estudo mostrou haver um aumento relevante da distorção luminosa perante a presença dos dois tipos de desfocado, sendo que ambos desfocados hipermetrópico e miópico produziram valores semelhantes de distorção, tanto em tamanho como irregularidade. A aberração esférica de alta ordem foi a aberração que mais influenciou as medidas de distorção, mas a pupila por si só não mostrou ter influência. Além disso, os índices topográficos SRI e SAI mostraram ser preditores de qualidade ótica ao relacionarem-se positivamente com o tamanho da distorção. O mesmo não se verificou entre a simulação da PSF e a medida psicofísica do LDA para ambos os desfocados positivos e negativo. Face aos resultados, verificamos que apesar da capacidade psicofísica do sistema binocular de atenuar os efeitos monoculares, não se deve descartar a importância e a necessidade de corrigir os baixos erros refrativos, não só por uma questão de melhoria da acuidade visual mas também de qualidade visual

Exposição - rostos da República : no âmbito das comemorações do Centenário da República em Espinho

O presente trabalho resume-se num relatório de Estágio. Estágio que foi desenvolvido no Fórum de Arte e Cultura de Espinho, na colaboração de um projecto de Equipa, concretizado numa Exposição cujo tema é os Rostos da República. Este projecto desenvolve-se no âmbito das Comemorações do Centenário da República em Espinho e a nível nacional (1910-2010). A Exposição gira em torno da Primeira República e dos rostos que caracterizam a sua importância, para isso, expõe uma lista de rostos a nível geral e local: os sete presidentes da Primeira República, vários nomes masculinos de elevada importância a nível nacional; mulheres que se representaram activamente na política e na defesa dos ideias feministas, e ainda rostos celebres de personagens locais, principalmente Espinho, seguindo-se por acrescento algumas personalidades de Santa Maria da Feira, Porto e Póvoa do Varzim. São sessenta painéis que caracterizam a Exposição, sendo que no Catálogo da Exposição figuraram oitenta e quatro personalidades. Assim sendo, o relatório descreve todo o meu contributo para a realização da Exposição, desde todo o processo de investigação à execução de biografias das figuras femininas activas no meio político e homens republicanos de Espinho

THE UNITED STATES OF AMERICA AND THE "NEW" ENEMY: THE BUSH ADMINISTRATION AND THE JUSTIFICATION FOR THE WAR ON TERRORISM

Este trabalho tem como objeto de estudo, a retórica de presidentes dos EUA na busca pela consolidação de uma opinião pública favorável à sua política externa, com destaque especial para a gestão do presidente George W. Bush filho. Tendo como base a busca dos EUA pela consolidação da sua liderança mundial, buscamos entender a importância dada para a configuração de um inimigo externo, seja no mundo bipolarizado da Guerra Fria, seja no cenário pós crise da URSS, com a eleição do terrorismo como inimigo preferencial. O objetivo é levar ao leitor compreensão sobre a influência que a retórica exerceu como principal ferramenta de justificativa e consolidação de um consenso sobre a importância de combate ao inimigo externo e o papel de liderança e hegemonia assumido pelos EUA.  Este trabajo tiene como objeto de estudio la retórica de los presidentes estadounidenses que buscan consolidar una opinión pública favorable a su política exterior, con especial énfasis en la administración del presidente George W. Bush, Jr. A partir de la búsqueda de Estados Unidos por la consolidación de su liderazgo mundial, buscaremos comprender la importancia que se le da a la configuración de un enemigo externo, ya sea en el mundo bipolarizado de la Guerra Fría, o en el escenario de crisis post-URSS, con la elección del terrorismo como enemigo preferido. El objetivo es que el lector comprenda la influencia que ejerció la retórica como principal herramienta para justificar y consolidar un consenso sobre la importancia de combatir al enemigo externo y el papel de liderazgo y hegemonía asumido por EE. UU.This work has as its object of study, the rhetoric of US presidents seeking to consolidate a public opinion favorable to their foreign policy, with special emphasis on the administration of President George W. Bush, Jr. Based on the US search for the consolidation of its world leadership, we will seek to understand the importance given to the configuration of an external enemy, whether in the bipolarized world of the Cold War, or in the post-USSR crisis scenario, with the election of terrorism as a preferred enemy. The objective is to provide the reader with an understanding of the influence that rhetoric exerted as the main tool for justifying and consolidating a consensus on the importance of combating the external enemy and the role of leadership and hegemony assumed by the USA

The impact of overnight orthokeratology on accommodative response in myopic subjects

This study aimed to evaluate the effects of two months of orthokeratology (OK) treatment in the accommodative response of young adult myopes. Twenty eyes (21.8 ± 1.8 years) were fitted with the Paragon CRT® 100 LENS to treat myopia between −1.00 and −2.00 D. Low- and high-contrast visual acuity (LCDVA and HCDVA), central objective refraction, light disturbance (LD), and objective accommodative response (using the Grand Seiko WAM-5500 open-field autorefractometer coupled with a Badal system) were measured at baseline (BL) before lens wear and after 1, 15, 30, and 60 nights of OK. Refractive error correction was achieved during the first fifty days of OK lens wear, with minimal changes afterwards. LD analysis showed a transient increase followed by a reduction to baseline levels over the first 30 nights of treatment. The accommodative response was lower than expected for all target vergences in all visits (BL: 0.61 D at 1.00 D to 0.96 D at 5.00 D; 60 N: 0.36 D at 1.00 D to 0.79 D at 5.00 D). On average, the accommodative lag decreases over time with OK lens wear. However, these differences were not statistically significant (p > 0.050, repeated-measures ANOVA and Friedman test). This shows that overnight OK treatment does not affect objectively measured the accommodative response of young, low myopic eyes after two months of treatment stabilization.This research was supported by the Portuguese Foundation for Science and Technology (FCT) PTDC/FIS-OPT/0677/2014, the Strategic Funding UID/FIS/04650/2013 at Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to A.A.S

O AGRONEGÓCIO, A EXPANSÃO DA TRANSGENIA E A EXPROPRIAÇÃO DE TERRAS NO POLO JUAZEIRO/PETROLINA

The expansion of irrigated agriculture in Petrolina centered on agribusiness policy has contributed to the increase of production and productivity through appropriation / expropriation in order to transform the cultivation, especially of corn, into commodity - exchange value. In this sense, the objective of the present research is to understand how land is appropriated by agribusiness, especially for the expansion of transgenics whose purpose is exchange - commodity value, contradictorily, has caused the expropriation of the peasants of the natural good (land) and the agroecological cultivation of corn to satisfy human needs, use value.A expansão da agricultura irrigada em Petrolina centrada na política do agronegócio tem contribuído para efetivar o aumento da produção e produtividade via apropriação/expropriação com o intuito de transformar o cultivo, especialmente, do milho, em mercadoria – valor de troca. Nesse sentido, o objetivo da presente pesquisa é compreender como as terras são apropriadas pelo agronegócio, especialmente, para a expansão da transgenia cujo intuito é valor de troca - mercadoria, contraditoriamente, tem provocado a expropriação dos camponeses do bem natural (terra) e do cultivo agroecológico do milho para satisfação das necessidades humanas, valor de uso.La expansión de la agricultura de regadío en Petrolina centrada en la política de agronegocios ha contribuido al aumento de la producción y de la productividad a través de la apropiación / expropiación con el propósito para transformar el cultivo, especialmente del maíz, en valor de intercambio de productos - mercadería. En este sentido, el objetivo de la presente investigación es comprender cómo las tierras son apropiadas por los agronegocios, especialmente para la expansión de los transgénicos cuyo propósito es el intercambio comercial: el valor de los productos básicos, contradictoriamente, ha provocado la expropiación de los campesinos del bien natural (la tierra) y cultivo agroecológico del maíz para satisfacer las necesidades humanas, valor de uso

Utilização do Cadastro Territorial Multifinalitário na gestão de riscos

Use of the multipurpose territorial cadastre on risk management - at first, this work presents a brief bibliographical review about records and risk management. After that, the methodology used on the execution of thematic maps through the Internet showing the characteristics of susceptible buildings to some type of risks is presented. Finally, it demonstrates the potential and viability of using this information on cadastres in this important area, while at the same time using minor financial resources

Impact of contact lens materials on the mfERG response of the human retina

Purpose To investigate the effect of different hydrophilic and rigid gas-permeable contact lens (CL) materials on multifocal electroretinography (mfERG). Methods The mfERG was recorded in 18 healthy subjects with RETI-port/scan21 (TM): 11 subjects underwent mfERG recording wearing two different hydrophilic CLs with different water contents in a randomized order (1 silicone hydrogel-Comfilcon A, 48%EWC, and 1 hydrogel-Omafilcon A, 62% EWC) and 7 other subjects wore a hydrophobic rigid gas-permeable scleral lens (SL)-Hexafocon A. Control measures were recorded without CL in both groups. mfERG recordings were performed with a stimulus array pattern of 103-scaled hexagons displayed on a 19-inch RGB monitor at 28 cm distance at a frame rate of 60 Hz. The amplitude (nV), implicit time and response density (nV/deg(2)) of the first-order kernel components N1, P1 and N2 were evaluated for the total mfERG response and for the response averages of 4 quadrants and of 6 successive concentric rings. Subjects were optically corrected for the working distance of ERG display. Results Hydrophobic material significantly decreased the P1 amplitude of the total mfERG response, at Rings 3, 4 and 6 and Quadrant 4 (> 53.77 +/- 43.2 nV; P <= 0.050), as well as the total (- 71.59 +/- 50.68 nV) and Ring 6 (- 104.76 +/- 79.88 nV) N2 amplitude (P <= 0.043). N1, P1 and N2 peak times suffered significant changes with both hydrophilic CL (P <= 0.050). Omafilcon A significantly increased P1 amplitude of Ring 5 and N2 amplitude of Ring 4, when compared to baseline (52.40 +/- 71.87 nV; P = 0.036) and to Comfilcon A (39.51 +/- 48.63 nV; P = 0.023), respectively. Conclusions Hydrophobic CL slightly attenuated the strength of the mfERG signal, especially at the middle to peripheral retinal areas, while hydrophilic CL slightly changed the implicit time of the response. Different hydrophilic CL materials might affect the mfERG response differently. When considering the measurement of mfERG obtained with a CL in place, researchers should bear in mind thThis project was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014 and the FCT Strategic Funding UID/FIS/04650/2013, FCT- SFRH/BPD/92365/2013 and SFRH/BD/136684/2018

Assessment of the human retinal neural selectivity to square gratings’ orientation with the multifocal and pattern electroretinograms

The retinal response to particular orientations might start a signaling cascade of events that help to modulate eye growth and respond to myopia control treatments. The purpose of this study was to investigate the retinal electrical activity in response to grids of different spatial orientations. The multifocal (mfERG) and pattern (PERG) ERG responses of nine eyes (spherical equivalent of −0.45 ± 1.15 D; mean age of 32.9 ± 7.7 years) were recorded with four grids (1.2 cpd) oriented at 60◦, 90◦ , 120◦ and 180◦ under pupils’ dilation. The mfERG was analyzed by retinal eccentricity, quadrants and meridians with the same orientation of the grids. The response density of mfERG, the amplitudes of PERG and the implicit times of each peak from both tests were analyzed. The grid’s orientation did not evoke different implicit times in both tests. All retinal meridians showed higher response density with grids of parallel orientation to the meridian and lower response density with perpendicularly oriented grids. These differences were statistically significant in the horizontal and 60◦ meridians (p < 0.050). PERG response did not change with the grids’ orientations. The mfERG was sensitive to detect changes in the outer retinal activity with variations in stimulus orientation. The paradigm of meridional analysis of mfERG results might be more sensitive to orientation changes than the traditional analysis by rings, quadrants or hemifields.This research was funded by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014, the FCT Strategic Funding UID/FIS/04650/2013, FCT-SFRH/BPD/92365/2013 and SFRH/BD/136684/2018

Retinal response of low myopes during orthokeratology treatment

The aim of this study was to evaluate the changes in retinal activity during orthokeratology (OK) treatment in 20 myopic eyes. Pattern electroretinography (PERG) and visual evoked potential (VEP) were assessed with the RETI-port/scan21 (Roland Consult, Wiesbaden, Germany). Measurements were taken at baseline (BL) and 1 night (1N), 15 nights (15N), 30 nights (30N), and 60 nights (60N) of OK lens wear. Repeated measures analysis of variance (ANOVA) and the Friedman test were used. Twenty eyes (23.20 ± 3.46 years, 70% female) with visual acuity ≤ 0.00 logMAR in post-treatment showed that despite a slight increase in retinal and cortical response amplitude, observed with both PERG and VEP, respectively, immediately after the initial treatment, these differences found were not statistically significant during the 60 days of OK treatment, despite a statistically significant increase in N95 response with PERG. This shows that retinal and cortical visual-related electrical activity is maintained or slightly increased during OK treatment.This research was supported by the Portuguese Foundation for Science and Technology (FCT) PTDC/FIS-OPT/0677/2014, the Strategic Funding UID/FIS/04650/2013 at Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to A.A.