The name retinitis pigmentosa defines a group of commonly inherited visual disorders, characterised by a progressive loss of vision. The disorder may be inherited in an autosomal dominant, recessive or X-linked recessive manner. Recently, three genes responsible for the autosomal dominant form have been identified: rhodopsin, RDS and ROM-1 on chromosomes 3,6 and 8 respectively. In this project, a panel of Scottish patients with a range of retinal degenerations including typical retinitis pigmentosa, Bardet-Biedl syndrome, Stagardts disease and cone rod dystrophy were screened for the presence of mutations in the rhodopsin and RDS genes using SSCP analysis, followed by direct sequencing to characterise the mutation. Four mutations within the rhodopsin gene and one in the RDS gene were detected and are likely to account for the phenotype in these individuals. Two polymorphisms, unrelated to the disease were also detected. Two of the four rhodopsin mutations and the RDS mutation change an amino acid residue in the corresponding proteins, whilst the third rhodopsin mutation alters the conserved splice site sequence in an intron. The effect of these mutations on the proteins is yet to be realised, but it is possible that they lead to the formation of a protein with impaired function, which in turn alters the biochemical or structural integrity of the rod cell and results in cell death. The fourth rhodopsin mutation occurs in the 3' untranslated region of the gene, but it is unknown whether this has any effect on the transcript or the protein. From the results of this study it is clear that mutations in the rhodopsin and RDS genes are a cause of retinitis pigmentosa, and also that SSCP analysis is an efficient mutation detection method.

No description available.

A Thesis presented to the Faculty of Science of the University of the Witwatersrand fo r the Degree of Doctor uf Philosophy. January 1979 / Clinical workers in binocular vision , known as o rth o p tis ts , have noticed variations in the binocular performance of patients which appear to have no relation to the ir visual state. Similarly there are some binocular tests, in p a rticu la r stereoscopic tests, which cannot be performed by normal students of the Optometry School. An in it ia l reading of the literature on binocular vision indicated that i t can be divided in to two parts, that concerning the mechanism which produces one visual percept from two visual inputs to the two separate eyes, and the mechanism which produces stereopsis, by evaluating the angular differences between the two re tin a l images and interpreting them as a sense of depth. I t was decided to concentrate on the haploscopic aspect of binocular vision , and to search fo r non-visual variables which determined the operation of th is function. A detailed reading of the lite ra tu re brought to lig h t several sets of experimental results showing marked v a ria b ility between normal subjects on the same te s t. Some of the operators commented on these, but did not look fo r th e ir o rig in . The neurological and neuro-anatomical lite ra tu re indicated that the production of the single visual percept was an on-going process which became more complex as i t was passed to higher neurological levels u n til the fin a l process was controlled by the cortex of the parietal lobe. This suggestion was confirmed by an E.F.G. programme carried out by the w rite r. The existence of neurological a c tiv ity in the parietal cortex involving the in h ib itio n processes which remove an unwanted diplopic image from visual perception suggested very strongly that psychological variables would be found here. This survey of the lite ra tu re also indicated that no previous work had been done in this fie ld and new tests had to be devised to isolate and measure the non-visual variables. This programme was undertaken by the w rite r who had done previous research in orthoptics and in optometry. These tests produced 20 scores, some of which suggested the psychological variable with which the optometric scores might correlate s ig n ific a n tly . The nature of these scores was described to a cross-discipline project team whose members designed a battery of tests, one psychological and the other neuro-psychological. The psychological battery was based on the assumption that the variable appeared to re late to some sort of psychological r ig id ity , but that as th is was not certain, certain other tests such as motivation, fru s tra tio n and suggestion must be adequately covered. The neuro-psychological battery assumed that the binocular variables must be measurable in the a c tiv ity of the central nervous system, and might appear as the muscular control of movement, or in the speeu of perception. A battery of te sts, including the E.E.G., was designed to measure these functions. The to ta l testing programme was now very large, and was given to two p ilo t samples. The battery was reduced in size by a study of the correlations, and by the use of cluster analysis. A study of the selected co rre la tio n between the binocular and the psychological scores indicated a relationship between the psychological results and some of the binocular tests. A reduced battery of both tests was given to a larger sample and a fa cto r analysis of the re su lt selected perseveration as the major psychological variable in binocular performance. During the course of the research work some very valuable discoveries were made fo r c lin ic a l optometry. The possible value of the results to psychology and the avenues of future research opened up by the programme of research are discussed.

MMed, Ophthalmology, Faculty of Health Sciences, University of the Witwatersrand / Aim To determine and document the demographic profile, clinical features, associations and clinical and visual outcomes in black African patients with idiopathic intracranial hypertension (IIH) attending St John Eye Hospital during 2006 and 2007. Method A retrospective descriptive study was conducted on black African IIH patients. Patient files and data of 21 of 32 IIH patients, seen in the Neuro-ophthalmology clinic at St John Eye Hospital over a two year period (2006 and 2007), were available and this study is based on these 21 patients. All 21 patients fulfilled the modified Dandy criteria for the diagnosis of IIH. Information obtained from files of the 21 patients were recorded on a data capture sheet. The demographics, initial (presenting) and final visual acuities and visual fields, initial and final clinical symptoms and signs, associations and treatment modalities were recorded on the data capture sheet. Visual and clinical outcomes were determined by comparing the final with the initial (presenting) symptoms and signs. The minimum follow-up period between the initial and the final visit was two months. Patients were regarded as legally blind if they had severe to profound visual acuity and/or visual field loss. Results All 21 patients were female and black African. Mean age was 31.2 ± 8.9 years (range 16 – 50 years). Mean period of follow up was 19.9 ± 20.1 months (range 2 – 77 months). 71.4% were obese. All patients presented with symptoms. The commonest presenting symptom was headache (90%) followed by visual loss (67%), transient visual obscurations (38%) and diplopia (29%). The results of the presenting signs were as follows: Seven eyes (17%) had visual acuity loss (most of which were mild [9.5%]), seven patients (33%) had abduction deficits, four patients (9.5%) had unilateral abnormal pupil reactions and all patients had papilloedema. Of the recorded associations seven patients (33%) were hypertensive, six (29%) were on contraception (two [9.5%] were on oral contraception) and two (9.5%) were taking prednisone prior to presentation. After the initial visit, all 21 vi IIH patients were treated with acetazolamide (Diamox) and weight loss was recorded in three patients (14%). Two patients (9.5%) had optic nerve sheath fenestrations (ONSF), two (9.5%) had lumbar-peritoneal shunts (LPS) and six (28.6%) had multiple lumbar punctures (LP’s). The outcome analysis was as follows: Symptoms in 19 patients (90%) improved but 16 patients (76%) still had papilloedema. Two patients (9.5%) had abduction deficits at the final visit. Visual acuity loss occurred in five eyes (12%) at the final visit compared to seven eyes (17%) at the initial visit (presentation). From the initial visit (presentation) to the final visit, visual acuity in seven eyes (16%) improved, 31 eyes (74%) remained stable and four eyes (10%) worsened. Although visual fields in 33 eyes (79%) improved from the initial to the final visit, 36 eyes (86%) still had visual field loss at the final visit. 26% of eyes had severe to profound visual impairment i.e. were legally blind, at the final visit. Conclusion The results of 21 black African IIH patients reported in this study were similar to some other studies with regards to demographics, clinical features and clinical and visual outcomes. An association between IIH and oral contraceptives, steroids and hypertension could not be established. Although symptoms resolved in most patients, a significant number of patients still had papilloedema and visual field loss following treatment. Despite treatment, a quarter of the patients were legally blind at the final visit, indicating that this condition is not benign.

Uma câmera pan-tilt é capaz de se movimentar em torno de dois eixos de rotação (pan e tilt), permitindo que sua lente possa ser apontada para um ponto qualquer no espaço. Uma aplicação possível dessa câmera é mantê-la apontada para um determinado alvo em movimento, através de posicionamentos angulares pan e tilt adequados. Este trabalho apresenta uma técnica de controle servo visual, em que, inicialmente, as imagens capturadas pela câmera são utilizadas para determinar a posição do alvo. Em seguida, calculam-se as rotações necessárias para manter a projeção do alvo no centro da imagem, em um sistema em tempo real e malha fechada. A técnica de rastreamento visual desenvolvida se baseia em comparação de uma região de referência, utilizando a soma dos quadrados das diferenças (SSD) como critério de correspondência. Sobre essa técnica, é adicionada uma extensão baseada no princípio de estimação incremental e, em seguida, o algoritmo é mais uma vez modificado através do princípio de estimação em multiresolução. Para cada uma das três configurações, são realizados testes para comparar suas performances. O sistema é modelado através do princípio de fluxo óptico e dois controladores são apresentados para realimentar o sistema: um proporcional integral (PI) e um proporcional com estimação de perturbações externas através de um filtro de Kalman (LQG). Ambos são calculados utilizando um critério linear quadrático e os desempenhos deles também são analisados comparativamente. / A pan-tilt camera can move around two rotational axes (pan and tilt), allowing its lens to be pointed to any point in space. A possible application of the camera is to keep it pointed to a certain moving target, through appropriate angular pan-tilt positioning. This work presents a visual servoing technique, which uses first the images captured by the camera to determinate the target position. Then the method calculates the proper rotations to keep the target position in image center, establishing a real-time and closed-loop system. The developed visual tracking technique is based on template region matching, and makes use of the sum of squared differences (SSD) as similarity criterion. An extension based on incremental estimation principle is added to the technique, and then the algorithm is modified again by multiresolution estimation method. Experimental results allow a performance comparison between the three configurations. The system is modeled through optical flow principle and this work presents two controllers to accomplish the system feedback: a proportional integral (PI) and a proportional with external disturbances estimation by a Kalman filter (LQG). Both are determined using a linear quadratic method and their performances are also analyzed comparatively.

O potencial visual evocado (PVE) é um sinal elétrico de baixa intensidade originado no córtex visual em resposta a uma estimulação visual periódica. O potencial visual evocado de varredura é um procedimento de PVE modificado para medir acuidade visual de grades em pacientes pré-verbais e não-verbais. Este biopotencial está imerso em uma grande quantidade de ruído eletroencefalográfico e artefato relacionado ao movimento. A relação sinal-ruído tem um papel dominante na determinação de erros sistemáticos e estatísticos. O propósito deste estudo é apresentar um método baseado na transformada wavelet para filtrar e extrair o potencial evocado visual de varredura. Grades de luminância de onda senoidal moduladas em 6 Hertz foram usadas como estímulo para se determinar os limiares de acuidade. A amplitude e a fase da 2ª. harmônica (12 Hertz) do padrão de resposta foram analisadas usando-se a transformada rápida de Fourier após a filtragem por wavelet. O método da transformada wavelet discreta foi usado para decompor o PVE em coeficientes wavelet, determinando-se quais destes representavam uma atividade significativa. Em um passo seguinte somente os coeficientes relevantes foram considerados, zerando-se os demais e reconstruindo-se, assim, o sinal PVE. Isto resultou na filtragem das demais freqüências que foram consideradas ruído. Simulações numéricas e análises com dados de PVE humanos mostraram que este método forneceu maior relação sinal-ruído quando comparado com o método clássico dos mínimos quadrados recursivo (RLS) e ainda uma análise de fase mais apropriada / Visually evoked potential (VEP) is a very small electrical signal originated in the visual cortex in response to periodic visual stimulation. Sweep-VEP is a modified VEP procedure used to measure grating visual acuity in non-verbal and preverbal patients. This biopotential is buried in a large amount of electroencephalographic noise and movement related artifact. The signal-to-noise ratio (SNR) plays a dominant role in determining both systematic and statistic errors. The purpose of this study is to present a method based on wavelet transform technique for filtering and extracting steady-state sweep-VEP. Counter-phase sine-wave luminance gratings modulated at 6 Hertz were used as stimuli to determine sweep-VEP grating acuity thresholds. The amplitude and phase of the second-harmonic (12 Hertz) pattern reversal response were analyzed using the fast Fourier transform after the wavelet filtering. The wavelet transform method was used to decompose the VEP signal into wavelet coefficients by a discrete wavelet analysis to determine which coefficients yield significant activity at the corresponding frequency. In a subsequent step only significant coefficients were considered and the remaining was set to zero allowing a reconstruction of the VEP signal. This procedure resulted in filtering out other frequencies that were considered noise. Numerical simulations and analyses of human VEP data showed that this method has provided higher SNR when compared with the classical recursive least squares (RLS) method. An additional advantage was a more appropriate phase analysis showing more realistic second-harmonic amplitude value during phase brake

I denna text försöker jag beskriva vad jag tänker kring mitt måleri och hur jag använder mig av mina synintryck. I bearbetningen av intrycken upplever jag att det inte finns några barriärer mellan det ena och det andra, så när det fungerar bra är en målning en uppvisare av vad perceptionen håller på med. Den spelar fritt. Den far runt hur den vill. Målningen kan hamna nära min visuella uppmärksamhet.

Thesis (MTech (Design))--Cape Peninsula University of Technology, 2018. / The youth faces unique challenges due to constant movement within the global economic and technological contexts. A digitally oversaturated world with constant access to globalised, mass information makes it challenging for communication designers to reach this audience on important matters. The South African context further complicates matters as youth unemployment is at an all-time high, a lack of quality schooling continues to feed poverty and inequality, exposure to gangs, violence, trauma and sexual abuse contribute to antisocial behaviour and drug and alcohol abuse increase risky sexual behaviour. It is therefore important to connect with the youth on these matters. The need to explore the mechanisms and content which will successfully connect with a South African youth audience was identified. In response to this, this study explored what the youth considers to be meaningful communication. The main objective of this research was to explore what types of visual communication have meaning for the youth to enable communication designers to connect with the South African youth market. The study used case study methodology and data was collected qualitatively through a questionnaire and participatory methods, including two co-design workshops (with 20 participants, aged 20-27) and a small group discussion (with 5 participants). The study featured a co-design approach, which focused on collaborative meaning-making through the visualisation of communication pieces. The study identified several interconnected themes which relate to a bigger category of association. Three major categories of understanding were identified: perception (how the youth see their world); engagement (how the youth experience their world); and relevance (how the youth relate to their world). These themes provide visual communication designers with valuable insights relating to the youth audience.

O Questionário de Função Visual Infantil (QFVI) é um instrumento para medir o impacto da deficiência visual na criança e em seus familiares. Pode ser utilizado como ferramenta para pesquisas, verificação da eficácia de tratamentos e de diferentes terapêuticas aplicadas, além de auxiliar métodos que intervenham com melhor eficiência, como habilitação e reabilitação visual. O objetivo deste trabalho é estudar a relação entre os domínios Saúde Geral, Saúde Geral da Visão, Competência, Personalidade, Impacto familiar e Tratamento, que compõem o QFVI, e as medidas psicofísicas de acuidade visual (AV) e discriminação de cromaticidade (VC). Este estudo prospectivo, transversal foi realizado no Laboratório de Psicofisiologia Sensorial da Universidade de São Paulo em parceria com o Ambulatório de Estimulação Visual Precoce Setor de Baixa Visão e Reabilitação Visual da Universidade Federal de São Paulo. As crianças convidadas a participarem deste estudo foram alocadas em 2 grupos: Grupo estudo (GE) composto por 32 crianças, com o diagnóstico de deficiência visual, com idade média de 30 meses (dp= 22,3); Grupo controle (GC) composto por 21 crianças, com visão normal e idade média de 34 meses (dp= 26,8). Esses grupos foram submetidos a aplicação do QFVI, e em seguida as avaliações de medida de AV através do teste de Cartões de Acuidade de Teller (CAT), e VC pelo programa Cambridge Colour Test para crianças (CCT Kids). O resultado da aplicação do QFVI, para os grupos de crianças menores de 3 anos, comparados entre os GE e GC, mostrou diferenças significantes entre os seguintes domínios: Saúde Geral da visão (F=24,07 e p<0,001); Competência (F=73,00 e p<0,001); Personalidade (F=10,21 e p=0,010); Impacto Familiar (F=35,30 e p<0,001); Total da qualidade de vida (F=64,06 e p<0,001). No teste de AV pelo CAT, nos grupos de crianças menores de 3 anos, comparados entre os GE e GC, foram observadas diferenças entre: AV de olho direito (OD) (F=12,86 e p<0,001); AV de olho esquerdo (OE) (F=11,09 e p<0,001); AV de ambos os olhos (AO) (F=16,27 e p<0,001). Estas diferenças mostram uma pior pontuação para o GE. Na VC medidos pelo CCT kids, os dados coletados nos grupos de crianças menores de 3 anos, comparados entre os GE e GC, não foram observadas diferenças estatisticamente significativas para os grupos Protan, Tritan, e Deutan para AO. Na aplicação do QFVI, os dados coletados nos grupos de crianças maiores de 3 anos, comparados entre os GE e GC, foram observadas diferenças entre os seguintes domínios: Saúde Geral da visão (F=10,00 e p<0,001); Competência (F=7,03 e p=0,030); Personalidade (F=6,48 e p=0,010); Total da qualidade de vida (F=11,39 e p=0,010). Estas diferenças mostram uma pior pontuação para o GE. No teste de AV pelo CAT, os dados coletados nos grupos de crianças maiores de 3 anos, comparados entre os GE e GC, foram observadas diferenças entre: AV de OD (F=19,25 e p<0,001); AV de OE (F=25,99 e p<0,001); AV de AO (F=15,45 e p<0,001). Estas diferenças mostram uma pior pontuação para o GE. No teste de VC pelo CCT kids, os dados coletados nos grupos de crianças maiores de 3 anos, comparados entre os GE e GC, não foram observadas diferenças estatisticamente significativas para os grupos Protan, Tritan, e ou Deutan. Para o GE, de crianças menores de 3 anos, a correlação negativa entre as funções visuais e o QFVI, está presente entre as seguintes variáveis: Saúde geral da visão e competência. Já para as crianças maiores de 3 anos: Saúde geral da visão, competência, impacto familiar e total da qualidade de vida. Nós concluímos que existem diferenças estatisticamente significativas quando comparados os GE e GC para as funções de acuidade visual e discriminação de cromaticidade, evidenciando a correlação no uso do QFVI e as funções de AV e VC / The Children\'s Visual Function Questionnaire (CVFQ) is an instrument to measure the impact of visual impairment in children and their families. It can be used as a research tool to verify the effectiveness of treatment, therapy and different methods for the visual stimulation and rehabilitation. The aim of this study is to describe the relationship between General Health, General Vision Health, Personality, Family Impact and Treatment subscales of the CVFQ, and psychophysical measures of visual acuity (VA) and chromaticity discrimination (CV). This prospective, cross-sectional study was conducted at the Sensory Psychophysiology Laboratory - University of São Paulo in partnership with the Ambulatory of Visual Stimulation in Sector of Low Vision and Visual Rehabilitation - Federal University of São Paulo. The children who participated in this study were divided into two groups: study group (SG) composed of 32 children with a diagnosis of visual impairment, mean age of 30 months (sd = 22.3); Control group (CG) consisted of 21 children with normal vision and mean age of 34 months (sd = 26.8). Both groups underwent the application of CVFQ, were tested for VA using the Teller Acuity Cards (TAC) test, and CV by the Cambridge Colour Test program for children (Kids CCT). The result of applying the CVFQ to groups of children under three years, when comparing SG and CG, showed significant differences in the following subscales: General Vision Health (F = 24.07, p <0.001); Competence (F = 73.00, p <0.001); Personality (F = 10.21, p = 0.010); Family Impact (F = 35.30, p <0.001); Total quality of life (F = 64.06, p <0.001). In the VA test by the TAC in groups of children under three years, comparing SG with CG, differences were observed in VA right eye (RE) (F = 12.86, p <0.001); VA left eye (LE) (F = 11.09, p <0.001); VA both eyes (BE) (F = 16.27, p <0.001). These differences show a worse score for the SG. In the CV measured by Kids CCT, the data collected in groups of children under three years, comparing SG and CG, no statistically significant differences for protan, tritan and deutan groups were observed for BE. In applying the CVFQ, the data collected from groups of children over three years, comparing SG and CG, differences were observed in the following subscales: General Vision Health (F = 10.00, p <0.001); Competence (F = 7.03, p = 0.030); Personality (F = 6.48, p = 0.010); Total quality of life (F = 11.39, p = 0.010). These differences show a worse score for the SG. In the VA test by the TAC, the data collected in groups of children over three years, comparing SG and CG, differences were observed in: VA RE (F = 19.25, p <0.001); VA LE (F = 25.99, p <0.001); VA BE (F = 15.45, p <0.001). These differences show worse score for the SG. In the CV by Kids CCT, the data collected in groups of children over three years, comparing SG and CG, no statistically significant differences for protan, tritan and deutan groups were observed. For the SG, children under three years, a negative correlation between the visual functions and the CVFQ was present for the following variables: General Vision Health and Competence, while for children over three years, correlations were found for General Vision Health, Competence, Family Impact and General Quality of Life. We conclude that there are statistically significant differences when comparing the SG with the CG for the visual function of VA and CV, and we also demonstrated the sensitivity in the use of CVFQ in reflect VA and CV impairments

Prior research has explored the counterchange model of motion detection in terms of counterchanging information that originates in the stimulus foreground (or objects). These experiments explore counterchange apparent motion with regard to a new apparent motion stimulus where the necessary counterchanging information required for apparent motion is provided by altering the luminance of the background. It was found that apparent motion produced by background-counterchange requires longer frame durations and lower levels of average stimulus contrast compared to foreground-counterchange. Furthermore, inter-object distance does not influence apparent motion produced by background-counterchange to the degree it influences apparent motion produced by foreground-counterchange. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection