The premise that mature visual function depends upon the nature of visual experience during development is based primarily on experiments showing that visual deprivation during a 'critical' period early in life causes abnormalities in visual cortex and an enduring loss of spatial vision (amplyopia). There is, however, little evidence that early visual experience atually enables mature vision. Experments in this thesis provide such evidence. The measurement of optomotor responses daily from eye opening permanently enhances optomotor sensitivity and the perception of visual motion. The plasticity allowing this enhancement is transient and peaks in efficacy before the start of the classical 'critical ' period for ocular dominance plasticity. The enhancement is dependent upon optomotor responses generated by the movement of high spatial frequency visual stimuli, and is mediated by the visual cortex. These studies show that a form of experience-dependent plasticity, distinct from that of the critical period, enables mature motion vision. / viii, 107 leaves : ill. (some col.) ; 28 cm.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 7 uppsatser.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 148-156).

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 74-84).

This research focuses on the grief and emotional reactions, especially frustration, of adventitiously visually impaired adults following loss of sight. The traditional grief-following loss theory with the assumption of a time-limited linear grief process, accompanied by diminishing emotions and culminating with acceptance and adjustment has been challenged. Chronic grief assumes a recurrent and continuous grief process, accompanied by increased emotions associated with continual losses related to a chronic loss, such as visual impairment. The question of whether there is a relation between length of time of adventitious visual impairment and the healing affect of time on grief and frustrations has been examined by quantitative and qualitative investigations. The answer to the question of whether time changes and heals everything is not necessarily the case. As always there are more questions than answers, and this research provides further insight into the real world of adventitious visual impairment. / Psychology / M.A. (Psychology)

A Distrofia Muscular de Duchenne (DMD) é uma doença recessiva ligada ao cromossomo X, causada por deleção ou mutação na proteína distrofina, e afeta 1 para cada 3.500 nascidos vivos do sexo masculino. O gene da distrofina é o maior gene do genoma humano e, além das proteínas de tamanho total, ao menos outras 5 isoformas foram identificadas até o momento. A isoforma total da distrofina e outras menores como a Dp260 (transcrita pelo promotor localizado no exon 30; encontrada na camada plexiforme externa da retina) e Dp71 (transcrita pelo promotor localizado no exon 63; encontrada nas células de Muller e membrana limitante interna da retina) são expressas na retina, dentre vários tecidos do corpo. Alterações nos eletrorretinogramas (ERG) de sujeitos com DMD já foram descritas na literatura. Redução da amplitude da onda-b e ERG negativo (razão das.amplitudes entre as ondas b e a menor que 1) são os achados mais comuns principalmente em sujeitos com deleção posterior ao exon 30. Embora estas alterações sejam conhecidas, poucos estudos avaliaram funcionalmente a visão destes sujeitos e, estes concluíram que os sujeitos com DMD apresentam visão de cores, acuidade visual e motilidade ocular normais. Como estas conclusões não refletem os achados eletrofisiológicos, o presente trabalho teve por objetivo aprofundar a avaliação de funções visuais em sujeitos com DMD, utilizando testes psicofisicos mais precisos e sensíveis que os métodos anteriormente empregados. Aplicamos uma bateria de testes que avaliou: a visão de cores (Cambridge Colour Test, Anomaloscópio de Neitz tipo I, lshihara e AO H-R-R) e a sensibilidade ao contraste de luminância (espacial e temporal), em 54 meninos (idade média =14,2 ± 4,1) com DMD, bem como o ERG em um subgrupo de 11 sujeitos. De acordo com a região da deleção no gene foram constituídos 3 grupos: grupo 1 (n=20) - sem deleção, grupo 2 (n=7) - com deleção anterior ao exon 30, grupo 3 (n=27) com deleção posterior ao exon 30. O grupo controle foi composto por 35 meninos com idade equiparada (médias = 15,4 ± 3,9). Os resultados mostraram que 52% dos sujeitos do grupo 3 apresentam defeitos de visão de cores. Surpreendentemente, a maioria destes sujeitos apresentou um defeito no eixo protan-deutan. Os três grupos apresentaram redução na sensibilidade ao contraste espacial e ao contraste temporal para todas as freqüências espaciais e temporais testadas. Houve uma tendência do grupo 3 de ter os piores resultados de contraste espacial. Para os resultados de contraste temporal, diferiram estatisticamente do grupo controle apenas os sujeitos do grupo 3 que tinham defeito de visão de cores. Os parâmetros do ERG de campo total replicaram os dados da literatura mostrando uma diminuição da amplitude e um aumento da latência da onda-b, além de uma razão b/a menor que l. A análise individual dos potenciais oscilatórios mostrou redução significante no 3° e no 4° potenciais, indicando que tanto a via dos cones quanto a dos bastonetes estão afetadas nos sujeitos com.DMD e deleção posterior ao exon 30. A constatação das maiores alterações de função visual nos sujeitos com deleção posterior ao exon 30 leva a sugerir que a distrofina Dp260 tem papel importante na fisiologia retiniana. Em conclusão, o presente trabalho demonstrou que a DMD é acompanhada por perdas visuais em várias funções e que estas perdas podem ser causadas principalmente por modificações na isoforma Dp260 da distrofina / Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder, caused by deletion or mutation in the protein dystrophyn, which affects 1:3500 live male births. The dystrophyn gene is the largest gene in the human genome. The full-length dystrophyn and at least other 5 isoforms have been identified. They are expressed in several tissues of the body including the retina, where the shorter isoforms Dp260 (transcribed by a promoter at the exon 30; founded in the outer plexiform layer of the retina) and Dp71 (transcribed by a promoter at the exon 63; founded in the Muller cells and inner limiting membrane of the retina) have been shown. Alterations in the electroretinograms (ERG) of these subjects have been described in the literature. 13-wave amplitude reduction and -a negative ERG (b/a wave amplitude ratio < 1) are the most common alterations found in subjects with gene deletion downstream exon 30, transcribes Dp260 isoform. Although these alterations are known, the only study that performed 1 evaluations of visual functions in these subjects concluded that they showed normal color vision, visual acuity and ocular motility results. Since these conclusions do not reflect the electrophysiological findings the objective of the present study was to further evaluate the visual function of DMD subjects using more sensitive and precise psychophysical tests than the methods used before. A battery of visual tests was used to evaluate color vision (Cambridge Colour Test, Neitz-1 Anomaloscope, Ishihara and AO H-R-R), luminance contrast sensitivity (spatial and temporal) in 54 boys (mean age = 14,2 ± 4,1) with DMD, and the ERG was also measured in a subgroup (n = 11) of these boys. According with the region of gene deletion, the subjects were divided in 3 groups: group 1 (n = 20) - without gene deletion, group 2 (n = 7) - with gene deletion upstream exon 30, group 3 (n = 27) - with gene deletion downstream exon 30. The control group was composed of 35 age-matched boys (mean-- 15,4 ± 3,9). Our results showed that 52% of the group 3 subjects had color vision defects. Surprisingly, almost all of these boys had a defect in the proten-deutan axis. In all three groups, spatial and temporal contrast sensitivities were lower than those of controls, for all spatial and temporal frequencies tested. Group 3 subjects had a tendency not statistically significant to present the worst results of spatial contrast sensitivities. Temporal contrast sensitivities were significantly different from controls' only for group 3 subjects with color vision defects. The full-field ERG results showed a b-wave amplitude reduction, a longer implicit time and a b/a ratio less than 1. Oscillatory potentials were significantly lower in the 3° and 4° potentials suggesting that that both cone and rod pathways were affected in the DMD subjects with deletion downstream exon 30. To our knowledge there are no descriptions of visual function defects in DMD subjects. The finding that the largest alterationslosses of visual function oceur in the subjects with deletion downstream exon 30 leads us to suggest that the dystrophyn Dp260 has an important role in the physiology of the retina physiology. In conclusion, the present study showed that DMD is accompanied losses in several visual functions and that these losses may be caused mainly by impairment in the Dp260 dystrophyn isoform

Orientador: Fausto Orsi Medola / Banca: Sergio Tosi Rodrigues / Banca: Milton José Cinelli / Resumo: A ausência da visão altera o padrão da marcha e a velocidade de caminhada, aumentando a dependência social e as chances de quedas e acidentes, comprometendo assim a mobilidade independente e a participação social. Dessa forma, é necessário o uso de dispositivos de Tecnologia Assistiva (TA), dentre os quais destaca-se a bengala: um bastão manual com ponteira que auxilia o usuário na orientação da trajetória e detecção de obstáculos. Embora a bengala contribua para a segurança e independência na mobilidade, nota-se ainda resistência na sua utilização, que pode ser explicada pela sua limitação no alcance de obstáculos, podendo ocasionar acidentes e riscos à saúde dos usuários. A bengala eletrônica surge como uma solução para este problema. Através do sensor ultrassom, ela detecta obstáculos acima da linha da cintura emitindo sinais sonoros e táteis. Para avaliar se a nova tecnologia é de fato mais eficiente para mobilidade dos usuários, este projeto de pesquisa propôs a comparação da eficiência de dois tipos de bengala - a tradicional e a eletrônica - através da execução de um trajeto com obstáculos artificiais, analisando o desempenho através das variáveis velocidade de caminhada e porcentagem de detecção de obstáculos. O estudo foi dividido em dois grupos amostrais: participantes vendados sem deficiência visual (N = 31) e participantes com deficiência visual (N = 10). O estudo também avaliou a usabilidade dos dispositivos segundo a perspectiva dos participantes, a satisfação d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The absence of vision changes the gait pattern and the walking speed, increasing social dependence and the chances of falls and accidents, thus compromising the independent mobility and social participation. Therefore, the use of Assistive Technology (AT) devices is necessary, among which stands out the white cane: a hand stick with a tip that helps the user in the path orientation and obstacles detection. Although the white cane contributes for safety and independence in the mobility, it is noted the resistance in its use, which can be explained by its limitation in the range of obstacles, which may cause accidents and risks to the user's health. The electronic cane arises as a solution to this problem. By the means of an ultrasonic sensor, it detects obstacles above the waistline sending sound and tactile feedback. To evaluate if the new technology is indeed more efficient for the users' mobility, this research project proposed the comparison of efficiency between two types of canes - the traditional white cane and the electronic cane - by the means of a performance of a path with artificial obstacles, analyzing the performance through the variables walking speed and obstacles detection percentage. The study was split into two sample groups: blindfolded participants without visual impairment (N = 31) and participants with visual impairments (N = 10). The study also evaluated the usability of the devices according to the participants' perspective, the AT users' satisfaction ... (Complete abstract click electronic access below) / Mestre

No / PURPOSE. Previous studies suggest that optimal reading speed is unaffected by cataract, yet is significantly reduced in age-related macular degeneration (ARMD ). This raises the question of whether a reading speed test could be developed to assess potential vision after cataract surgery. METHODS. Nineteen subjects with cataract, 15 with ARMD, and 13 control subjects with normal, healthy eyes read Bailey-Lovie word charts aloud, and subsequently, critical print size and optimal reading speed were calculated. Measurements were also taken with the charts in reversed-contrast polarity and after pupillary dilation. RESULTS. Although the subjects with cataract had reduced word acuity and increased critical print size, optimal reading speed was similar to that of the control group at a mean of approximately 100 wpm. Optimal reading speed in the subjects with ARMD was substantially worse (mean of 39 wpm). Reversing the contrast polarity of the charts slightly increased the word acuity and optimal reading speed of the subjects with cataract. CONCLUSIONS. The results suggest that optimal reading speed would be useful as a potential-vision test. The proposed test would use text size of at least 1.32 degrees (1.2 log minimum angle of resolution [logMAR]), and pupil dilation would be unnecessary. A reading test with black letters on a white background would be adequate, because charts with reversed-contrast polarity made minimal difference in reading speed.

Text in Afrikaans / Summaries in Afrikaans and English / Die doel met hierdie studie is om 'n kurrikulum vir die onderwys van swaksiende kinders vanui t 'n makroperspektief te ontwerp. Van die belangrikste gevolgtrekkings waartoe in hierdie studie gekom word, dui daarop dat die kurrikula, leerplanne en -opleidingsprogramme wat in die Republiek van Suid-Afrika vir kinders met spesiale onderwysbehoeftes (wat die onderwys van swaksiende kinders insluit) voorsien word * dikwels nie toereikend is om leerlinge vir suksesvolle indiensplasing voor te berei nie; * oorwegend akademies georienteerd is; * en nie altyd tred hou met die veranderende behoeftes, eise en tendense in die arbeidsmark nie. Swaksiende kinders is as groep hoogs heterogeen en het besondere en uiteenlopende onderwys- en opleidingsbehoeftes. Ten einde 'n relevante kurrikulum vir swaksiende kinders te on twerp wat genoemde leemtes ondervang, moes hulle uni eke behoef tes sowel as die eise van die moderne arbeidsmark in aanmerking geneem word. Die voorgestelde kurrikulum is op die onderwys van swaksiende kinders in af sonderlike skole vir gesiggestremde kinders en in skole in die hoof stroom van die onderwys van toepassing en maak * enersyds voorsiening vir die effektiewe implementering van die kurrikulum wat deur die Suid-Afrikaanse onderwysowerheid op nasionale (en moontlik ook op provinsiale) vlak vir die onderwys van normaalsiende kinders voorgeskryf word, en * andersyds vir die ontsluiting en bemeestering van die noodsaaklike kompensatoriese persoonlikheids- en karaktereienskappe en algemene vaardighede, waaroor swaksiende kinders behoort te beskik ten einde hulleself na skoolverlating in die volwasse sosiale en beroepslewe te kan handhaaf. Die kurrikulummodel wat die basis vorm vir die ontwerp van hierdie kurrikulum, is sodanig aangepas dat dit uitdrukking gee aan die essensies van 'n Christelik-wysgerige perspektief op opvoeding en onderrig. / The aim of this study is to design a curriculum for the education of partially sighted children from a macro perspective. some of the most important conclusions arrived at in this study indicate that the present curricula, syllabi and training programmes which are being offered to children with special education needs (including the education of partially sighted children) in the Republic of South Africa * are often not adequate to prepare learners for successful placement; * are predominantly academically orientated; * and do not always keep track with changing needs, demands and tendencies in the labour market. Partially sighted children as a group are highly heterogeneous and have particular and diverse education and training needs. In order to design a relevant curriculum for partially sighted children which intends to eradicate the mentioned deficiencies in the present provision of education to them, their unique needs as well as the demands of the modern labour market have to be considered. The proposed curriculum is directed at the education of partially sighted children who are accommodated in separate schools for the visually impaired as well as in schools in the mainstream of education and provides * on the one hand for the effective implementation of the curriculum which is prescribed normally sighted children by for the education of the South African education authorities on national (and perhaps also on provincial) level and * on the other hand for the unlocking and mastering of the essential compensatory personality and character qualities and general skills which partially sighted children should possess in order to maintain themselves in the adult social and vocational life after leaving school. The curriculum model which formed the basis for the design of this curriculum was adadapted in such a way that it expresses the essence of a Christian philosophic perspective on education and teaching. / Teacher Education / D.Ed.

Blindness is one of the most debilitating health disorders and avoidable blindness is a major international health problem. The World Health Organization has estimated that globally, there are 45 million persons who are blind - a figure that is expected to increase to approximately 76 million by the year 2020. Approximately 80% of blindness is avoidable and can be prevented or cured with appropriate service delivery efforts. Research suggests that the combined annual global GDP loss from blindness in 2000 was more than $40 billion. Yet blindness has received relatively little attention in worldwide efforts to promote health and it is not at present a high health priority in many countries. Consequently, unless there are alternative and more efficient and extended endeavours to address this situation and model an approach that will provide a long-term solution, avoidable blindness will continue. In recent years, eye care service delivery organisations have assumed a greater level of responsibility for addressing the problem of avoidable blindness. A number of successful approaches have been designed and implemented to expand the delivery of eye care services. The approaches have focused on the development of organisational capacity and on sustainability, and they have effectuated a reduction in avoidable blindness in particular target populations. However, despite their importance, contemporary eye care service delivery models have largely been neglected in the literature and few formal organisational approaches to eye care have been developed and documented. There are few definitive independent studies available that outline the bases of these approaches and no explicit and standardised methodologies that can assist service delivery organisations to replicate the approaches. Objective and comprehensive research is accordingly required to promote current and new approaches to eye care and to develop ways of facilitating their adoption. The thesis attempts to address this problem by developing a theory&ndash;based, case study&ndash;supported practical methodology to identify, support the progression of, and measure the strategic and operational objectives of eye care service delivery organisations. The research seeks to identify the issues relevant to the management of eye care service delivery organisations and subsequently evaluate whether they can be incorporated into a distinct and explicit management framework. It seeks to present the value of the process and the possibility that it can be accomplished elsewhere and in dissimilar organisations. By developing a widely applicable management framework, the research's primary contribution is that it extends eye care organisational management theory to assist in the facilitation of blindness reduction. A conceptual management framework is developed in the thesis which unifies contemporary eye care organisational approaches with the Balanced Scorecard management framework. The framework was devised for and evaluated by undertaking two case studies &ndash; one in India and one in South Africa. The significance of developing such a framework is demonstrated at various points throughout the thesis. The research process reveals the potential applicability of the framework &ndash; the Strategic Management Framework (SMF). The research concludes that the SMF is able to support and enhance organisational development, performance management, and scenario analyses in eye care service delivery organisations operating in developing countries. Although the framework developed in the thesis is specific to eye care organisations it is flexible enough to be transferable to other healthcare organisations in developed countries. The final conclusion of the thesis is that, while the SMF is not in itself a solution to the problem of avoidable blindness, it is an appropriate and practical management tool which will improve existing, and assist in the establishment of new, eye care service delivery organisations. In this context, the research makes a number of significant and original contributions to prevention of blindness literature and theory. / Thesis (Ph.D.)--School of History and Politics, 2004.