Dissertations / Theses on the topic 'Ametropía'

Introducción: En nuestro país los estudios relacionados a los defectos de refracción ocular son poco estudiados, a pesar del incremento de las investigaciones a nivel mundial por determinar los factores causales de estas, entre los que se ha planteado múltiples factores como los genéticos y ambientales, y dentro de estos últimos, se hallan algunos factores sociodemográficos como el lugar de residencia, el nivel de educación y el nivel socioeconómico. Objetivo: El objetivo del presente estudio es determinar si existe alguna asociación entre el desarrollo de un defecto de refracción y algunos factores sociodemográficos en población de entre 6 a 11 años de edad. Diseño: Estudio de casos y controles. Población de estudio: Personas de 6 a 11 años que forman parte de la ENDES 2014. Metodología: Se obtuvo la base de datos del ENDES 2014 de la página web del INEI, la cual se procesará en el software SPSS versión 23 para seleccionar los casos a estudiar y hacer el análisis. Para determinar si existe asociación entre los factores sociodemográficos y los errores de refracción, se hará uso del odds ratio y la prueba de chi cuadrado. Resultados: Se obtuvo 2220 casos acorde a los criterios de selección y exclusión. El 21.6% de presentaba un diagnóstico de error refractivo. La miopía fue el error refractivo con mayor prevalencia (14.46%), seguido del astigmatismo (6.31%) y la hipermetropía (0.86%). Se encontró asociación de riesgo, a nivel general, conforme aumenta el nivel de riqueza (Pobre [p=0.001]: OR=2.72; IC-95%:1.53-4.85. Medio [p<0.001]: OR=6.53; IC-95%:3.59-11.87. Rico [p<0.001]: OR=10.26; IC-95%:5.49-19.17. Muy rico [p<0.001]: OR=17.62; IC-95%: 9.42-32.98) y en población urbana (p=0.036; OR=1.56; IC-95%:1.03-2.37). No se encontró asociación con el sexo, edad, nivel de educación y región de procedencia. En el análisis por separado de las ametropías estudiadas, la miopía presenta el mismo tipo de asociación con el nivel de riqueza y el tipo de lugar de procedencia, mas no la hipermetropía ni el astigmatismo, cuadros en los que no se encontró asociación con ni una las variables sociodemográficas estudiadas. Conclusiones: A partir de lo encontrado en este estudio, se puede señalar que existen determinadas características socioeconómicas que pueden considerarse como factores que pueden influir en el desarrollo de las ametropías, en especial de la miopía (cuadro en el que se encontraron las mismas asociaciones que a nivel general), como son el nivel de riqueza y el tipo de lugar de residencia. Palabras clave: Errores de refracción, ametropías, factores sociodemográficos, escolares.
--- Introduction: In our country, studies related to ocular refractive defects are little studied, despite the increase in global research to determine the causal factors of these, of which has been raised many factors such as genetic and environmental, and within the latter, sociodemographic factors such as place of residence, education level and socioeconomic status are. Objective: The objective of this study is to determine whether there is any association between the development of a refractive defect and sociodemographic factors in population aged 6-11 years old. Design: Case-control study. Study population: People from 6 to 11 years as part of the ENDES 2014. Methodology: The database ENDES 2014 was obtained from INEI website, which will be processed in SPSS version 23 software; to determine the association between sociodemographic factors and refractive errors will be obtained using the odds ratio and chi-square test. Results: 2220 cases was obtained according to the selection criteria and exclusion. 21.6% had a diagnosis of refractive error. Myopia refractive error was the most prevalent (14.46%), followed by astigmatism (6.31%) and hyperopia (0.86%). Risk association was found, in general, as the level of wealth (Poor [p=0.001]: OR=2.72; 95%-CI:1.53-4.85. Medium [p<0.001]: OR=6.53; 95%-IC:3.59- 11.87. Rich [p<0.001]: OR=10.26; 95%-CI:5.49-19.17. Very rich [p <0.001]: OR=17.62; 95%-CI:9.42-32.98) and urban population (p=0.036; OR=1.56; 95%-CI:1.03-2.37). No association with gender, age, education level and region of origin was found. In the separate analysis of the ametropies studied, myopia has the same type of association with the level of wealth and the kind of place of origin, but not farsightedness or astigmatism, diseases in which no association was found with nary a sociodemographic variables. Conclusions: From the findings in this study, we can say that there are certain socioeconomic characteristics that can be considered as factors that may influence the development of ametropia, particularly myopia (table showing the same associations they found that a general level), such as the level of wealth and the kind of place of residence. Key words: refractive errors, ametropies, sociodemographic factors, schoolchildren.
Tesis

Introducción: Al ser la agudeza visual inherente al ser humano y la educación escolar necesaria para el desarrollo del niño y del fortalecimiento social, sumando la escaza información sobre dicha relación en nuestra realidad, entra en contexto el desarrollo de la presente investigación. Objetivo General: Determinar la asociación entre la Agudeza Visual y el Rendimiento Escolar en Comunicación en la I.E N° 7215 “Naciones Unidas” UGEL 01 SJM, Lima, 2016. Materiales Y Métodos: Se realizó un estudio cuantitativo, de tipo observacional, analítico, caso y control; la muestra la conformaron 60 casos y 55 controles, se tomó registro de la agudeza visual de los escolares, con la Cartilla de Snellen y Agujero Estenopeico, además de sus calificaciones en el curso de comunicación. Resultados: El 44.3% de escolares presentaron agudeza visual alterada, el Impedimento Visual Leve se presentó en un 41.2% y 43.1% para el ojo derecho e izquierdo respectivamente, siendo la alteración más frecuente. El 31.3% presentó anomalías refractivas y un 13% no refractivas. Al asociar las anomalías no refractivas con el rendimiento se obtuvo un OR 4.828 (IC 95% 1.242 - 18.762, p = 0.016). Conclusión: La anomalía visual no refractiva constituye un factor de riesgo para tener bajo rendimiento escolar en el curso de Comunicación.

Refraction simulators used for undergraduate training at Aston University did not realistically reflect variations in the relationship between vision and ametropia. This was because they used an algorithm, taken from the research literature, that strictly only applied to myopes or older hyperopes and did not factor in age and pupil diameter. The aim of this study was to generate new algorithms that overcame these limitations. Clinical data were collected from the healthy right eyes of 873 white subjects aged between 20 and 70 years. Vision and refractive error were recorded along with age and pupil diameter. Re-examination of 34 subjects enabled the calculation of coefficients of repeatability. The study population was slightly biased towards females and included many contact lens wearers. Sex and contact lens wear were, therefore, recorded in order to determine whether these might influence the findings. In addition, iris colour and cylinder axis orientation were recorded as these might also be influential. A novel Blur Sensitivity Ratio (BSR) was derived by dividing vision (expressed as minimum angle of resolution) by refractive error (expressed as a scalar vector, U). Alteration of the scalar vector, to account for additional vision reduction due to oblique cylinder axes, was not found to be useful. Decision tree analysis showed that sex, contact lens wear, iris colour and cylinder axis orientation did not influence the BSR. The following algorithms arose from two stepwise multiple linear regressions: BSR (myopes) = 1.13 + (0.24 x pupil diameter) + (0.14 x U) BSR (hyperopes) = (0.11 x pupil diameter) + (0.03 x age) - 0.22 These algorithms together accounted for 84% of the observed variance. They showed that pupil diameter influenced vision in both forms of ametropia. They also showed the age-related decline in the ability to accommodate in order to overcome reduced vision in hyperopia.

Na prática clínica na área de Optometria utiliza-se o rácio C/D linear, entre outros parâmetros, para caracterizar a normalidade da zona papilar. Nos estudos já efectuados constatou-se que não se recorria à análise da totalidade da área da papila. A experiência clínica permitiu a verificaçao de inúmeros casos em que o rácio C/D linear era distinta do rácio C/D área. Neste estudo analisámos a totalidade da área papilar para obter uma caracterização mais completa e determinar as novas relações deste parâmetro com outros dados fisiológicos como a idade, PIO e ametropia. Foram analizados 300 indivíduos saudáveis com idades compreendidas entre os 40 e 65 anos, PIO entre 10 e 21 mmHG, miopias até 6.00D, hipermetropias até 5.00D e astigmatismos iguais ou inferiores a 1.00D. Verificou-se que não existe nenhuma correlação entre o C/D área, idade, PIO e ametropia. O valor médio do racio C/D área para a amostra estudada é de 0,29.

In this thesis the laser ray tracing (LRT) technique for measurement of ocular aberrations has been implemented, validated and applied, in conjunction with complementary techniques, to the study of ocular aberrations in human eyes. In particular, we studied optical aberrations in myopic and hyperopic eyes and the optical changes induced by refractive surgery for myopia and hyperopia. We have studied the impact of the optimisation of some experimental parameters on the estimation of the wave aberration. We demonstrated that although the polarisation state and wavelength of the illumination light affected the intensity patterns of the images obtained using reflectometric aberrometry (LRT and Hartmann Shack sensor), these changes did not affect the estimation of aberrations. We also showed that the difference in the defocus term (focus shift) due to the use of different wavelengths is in agreement with the Longitudinal Chromatic Aberration of the Indiana Chromatic Eye Model for average normal eyes, although intersubject variability is not negligible. In addition, we studied experimentally the influence of the geometrical distribution and density of the pupil sampling on the estimation of aberrations using artificial and normal human eyes, and performed numerical simulations to extend our results to "abnormal"eyes. We found that the spatial distribution of the samples can be more important than the number of samples, for both our measured as well as our simulated "abnormal" eyes. Experimentally, we did not find large differences across patterns except, as expected, for undersampled patterns. We found that hyperopic eyes tended to have more positive asphericity and greater total and corneal spherical aberrati on than myopic eyes, as well as greater 3rd and higher order aberrations. Although we found no significant differences between groups in terms of internal aberrations, internal spherical aberration showed a significant age-related shift toward less negative values in the hyperopic group. We also assessed the impact of the LASIK corneal surgery, a popular surgical technique for correction of refractive errors, on the optical quality for both myopic and hyperopic standard techniques. Third and higher order ocular and an terior corneal aberrations increased with the surgery. Ocular and corneal spherical aberration changed towards more positive values with myopic LASIK, and towards more negative values with hyperopic LASIK. Changes in internal spherical aberration were of opposite sign than those induced in corneal spherical aberration. Changes induced by hyperopic LASIK were larger than those induced by myopic LASIK for a similar attempted correction.

Syfte: Att undersöka förekomst av hyperopi i förhållande till läskunnighet hos hjälpsökande hos VFA i Bolivia, samt jämföra med studier från andra delar av världen.

Metod: Studien utfördes i april 2010 på tre olika orter i centrala Bolivia. Patienterna sökte själva upp platsen för att få en undersökning. Subjektiv refraktion utfördes binokulärt, utan dimning, med hjälp av provbåge, provlåda och syntavla med Snellen E, uppsatt på 5 meters avstånd. Hyperopi räknades som sfärisk ekvivalent ≥ +1,00 D, myopi som ≤ –0,25 DS.

Resultat: 1 313 personer undersöktes, varav 1 271, mellan 6 och 92 år gamla, ingick i studien. Förekomsten av hyperopi var totalt 23,8% (som mest 39,8% hos kvinnor 66-92 år gamla, och som minst 10,7% hos kvinnor 6-19 år gamla), läskunnighet totalt var 81,7% (kvinnor 74,7%, män 90,7%). Det var något lägre läskunnighet bland hyperoper (78,1%) än bland myoper (83,2%) och emmetroper (82,7%).

Slutsats: Bolivia verkar ha större förekomst av hyperopi än Asien och Europa. Hyperopi ökar med åldern, främst efter 50-årsåldern. Miljöfaktorn ser ut att ha viss betydelse.

A elaboração deste relatório, afigura-se como o culminar do período de estágio que foi desenvolvido entre o mês de Novembro de 2011 e o mês de Maio de 2012 na Clínica Oftalmológica Professor Doutor Manuel Monteiro Pereira, no Porto. O estágio consistiu no acompanhamento de consultas, cirurgias, realização e análise de exames complementares de diagnóstico, com o intuito de consolidar conhecimentos de correção e tratamento das diversas ametropias, com principal destaque para a miopia. Promovendo assim, uma maior sensibilização para este tema, uma vez que se trata da ametropia com maior grau de prevalência a nível mundial.
In this report, appears as the culmination of the probationary period that was developed between November 2011 and May of 2012 at the Clínica Oftalmológica Professor Doutor Manuel Monteiro Pereira, Oporto. The stage consisted of follow-up consultations, surgeries, conduct and analysis of diagnostic exams, in order to consolidate knowledge of correction and treatment of various refractive errors, with main focus on Myopia. Thus promoting a greater awareness of this issue, since it comes with a higher degree of ametropia prevalence worldwide.

Syfte: Syftet med studien var att, med hjälp av Optical Coherence Tomography (OCT), undersöka om det finns någon skillnad i central och perifer retinal tjocklek mellan olika ametropier. Metod: Studien omfattade 36 försökspersoner, som grupperades beroende på ametropi i en myop, emmetrop och hyperop grupp. Av de 36 försökspersonerna var det 15 myoper, 15 emmetroper och 6 hyperoper. En inledande mätning gjordes där försökspersonernas objektiva refraktion uppmättes med autorefraktor och därefter gjordes en avstämning i provbåge för att säkerställa refraktionen. Med OPKO Spectral OCT/SLO mättes retinas tjocklek både centralt och perifert på höger öga. För att analysera resultatet delades retina in i 15 olika zoner som jämfördes mellan de olika ametropierna. Resultat: Resultatet av studien visade en signifikant skillnad i foveal tjocklek mellan de olika ametropierna (p=0,03). Det var en siginifikant skillnad i retinal tjocklek mellan retinas zoner i alla tre ametropier (p<0,01), dock var det ingen signifikant skillnad i perifer retinal tjocklek mellan de tre olika ametropierna (p=0.07). Slutsats: Ingen skillnad i central och perifer retinal tjocklek kunde redovisas mellan de olika ametropierna. Då en tidigare studie har visat att den retinala tjockleken skiljer sig mellan olika ametropier kan resultatet av vår studie diskuteras då det i vår studie fanns brister som få antal personer, olika antal personer inom grupperna och en låg utbredning av synfel.

The increasing prevalence of myopia over the past few decades and its association with potential ocular complications make myopia an important research topic. The present work is concerned with the structural and functional characteristics of a group of myopic and emmetropic individuals. The technical experiments in this work investigated firstly the effect of instrument alignment on peripheral refraction measurements and revealed that the corneal vertex was an acceptable alignment position of the Shin-Nippon NVision-K 5001 autorefractor, allowing consistent alignment with other instruments used in this research. Secondly, spectacles could be used to provide comparable vision to contact lenses in the visual performance studies. In the main experimental parts of this work, visual performance and multiple aspects of ocular structure were assessed across a wide range of eccentricities along the horizontal and vertical meridians within the same eyes. The structural properties of the myopic eye were measured through central and peripheral autorefraction, and through cornea to retina dimensions using non-contact biometry. In addition, the central and peripheral resolution acuities of myopic and emmetropic eyes for high and low contrast levels were investigated. Our structural and functional measurements revealed relatively prolate myopic eyes with reduced high contrast resolution acuity, compared to emmetropic eyes. Moreover, multiple regression analyses were performed at the fovea and outermost retinal eccentricities common to all core experiments but revealed no strong relationship between the structure and function of the myopic eye. Finally, regarding asymmetry, the nasal and superior retinae were found to be longer and to perform better in comparison to the temporal and superior retinae respectively.

RESUMO: Na parte inicial incluem-se algumas notas sucintas com base no panorama científico,histórico e cultural da visão considerada segundo três abordagens - o olho (o olho humano na especificidade da sua posição filogenética, elemento anátomo-funcional básico do sistema visual ao qual o cérebro pertence), os olhos (unidades gémeas essenciais do rosto na sua actividade consensual e conjugada da binocularidade), o olhar (carregado de expressão psicológica e o seu efeito sobre o observador, sinal para o comportamento e criador de sentimentos, sedimentado em obras de arte e em formas de superstição dos povos). Segue-se a apresentação de um estudo descritivo transversal, como contribuição para o conhecimento do estado de saúde visual da população infantil da região de Lisboa e determinar factores que o influenciam. Entre Outubro de 2005 e Agosto de 2006 examinaram-se 649 crianças com idade inferior a 10 anos da Consulta de Oftalmologia Pediátrica dos Serviços de Assistência Médico-Social do Sindicato dos Bancários do Sul e Ilhas (SAMS). Colheram-se dados respeitantes a mais de 250 variáveis primárias que cobriram a maior parte dos itens do exame oftalmológico habitual. Na análise dos dados teve-se especialmente em conta a idade, com um papel decisivo nas principais fases de desenvolvimento do sistema visual. No caso das crianças de 6 a 7 anos de idade põem-se lado a lado resultados dos SAMS e das Escolas. A profusão de dados numéricos ditou a necessidade da determinação frequente da significância estatística dos resultados de subgrupos. Alguns resultados do estudo, na sua maioria do grupo SAMS: Crianças de 6-7 anos, 71,1% (SAMS) e 91,5% (Escolas) não tinham sido examinadas com menos de 4 anos. Frequência global de alterações miópicas 9,4%, de alterações hipermetrópicas 25,3%, umas e outras com variações acentuadas com a idade. Estrabismo convergente 3,9%. Ambliopia 2,6% (13/491 crianças >=4 anos de idade), mais frequente no sexo feminino, naquelas que tiveram a sua 1ª observação depois dos 4 anos e em que os pais não aderiam à terapêutica prescrita. Objectivos específicos ocuparam-se da acuidade visual e da refracção ocular. O estudo comparativo da refractometria automática sem e com cicloplegia permitiu evidenciar que o teste da acuidade visual é insuficiente, por si só, para fazer o diagnóstico correcto. A análise dos antecedentes familiares oftalmológicos demonstrou a importância do seu conhecimento e pôs em evidência, entre outras, as seguintes relações: 10 pag1.qxp 27-11-2001 18:28 Page 10 Índice Geral 11 Crianças com antecedentes de alterações miópicas têm maior frequência de diagnóstico de alterações miópicas e de refracção negativa, uma taxa mais elevada de correspondência quantitativa diagnóstico/refracção nas alterações miópicas. Estas crianças também têm, em geral, características inversas no que diz respeito a alterações hipermetrópicas. Crianças com antecedentes de alterações hipermetrópicas têm maior frequência de diagnóstico de alterações hipermetrópicas. Crianças com antecedentes de estrabismo têm maior frequência de diagnóstico de estrabismo convergente manifesto e de esodesvios no seu todo. Crianças com antecedentes familiares de astigmatismo têm maior frequência de diagnóstico de astigmatismo. Traçam-se alguns perfis oftalmológicos infantis que permitem apreciar de forma sinóptica um conjunto de parâmetros da saúde da visão. Os dados colhidos sobre a aderência dos pais à terapêutica prescrita e sobre a atitude em relação ao uso de óculos assim como os dados sobre o comportamento da criança na sala de aula e dificuldades de aprendizagem foram em geral escassos para permitirem tirar conclusões, embora mostrem indícios a investigar futuramente. Paralelamente ortoptistas e enfermeiras efectuaram um rastreio escolar da acuidade visual <0,8 e de alterações da motilidade ocular extrínseca que abrangeu 520 alunos do 1º ano do 1º ciclo do ensino básico (2005/2006) das escolas públicas da cidade de Lisboa. 101 destas crianças foram observadas no consultório da autora, umas referidas a partir do rastreio, outras como controlo deste. Quanto à acuidade visual o valor preditivo do teste negativo foi de 91% mas o do teste positivo de apenas 67% (33% de falsos positivos, consequentemente uma alta taxa de sobrerreferenciação). A qualidade do rastreio efectuado por ortoptistas foi inferior à do efectuado por enfermeiras. O rastreio não teve qualidade aceitável. Foi feito um inquérito a médicos e enfermeiros de centros de saúde sobre conhecimentos, atitudes e práticas em relação com os cuidados de oftalmologia pediátrica. Discutem-se os resultados, tiram-se conclusões e fazem-se recomendações susceptíveis de contribuir para uma melhor saúde visual das crianças. ABSTRACT: Firstly some brief remarks are made based on the scientific, historical and cultural panorama of the human vision with regard to three approaches: the eye (the human eye in its specific filogenetic place, fundamental anatomofunctional element of the visual system in interaction with the brain), the eyes (essential twin units of the face with their consensual and conjugated binocular activity), the gaze (psychologicaly overloaded, a means to express oneself and to influence the observer, a guide to other persons' behaviour, consolidated in works of art and in people's traditional superstitious believes and ways of thinking). A report is made on a cross-sectional descriptive study whose goal is to contribute to the knowledge of the level of visual health of children in the Lisbon Region and to identify factors which determine it. Between October 2005 and August 2006 649 children under 10 years were observed at the pediatric ophthalmologic consultation in the SAMS (Serviços de Assistência Médico-Social do Sindicato dos Bancários do Sul e Ilhas). Data were collected concerning more than 250 primary variables covering most itens of the usual ophthalmological examination. Special attention was paid to children's age since it plays a crucial role in main stages of visual system development. In the case of children age 6 to 7 SAMS and school results are often put side by side. On account of the great number of numerical data it was often necessary to look at the degree of statistical significancy of differencies between subgroups. Some of the study's results (mostly SAMS): Children age 6 to 7 - 71,1% (SAMS) and 91,5% (Schools) had not an ophthalmologic examination before 4 years old. Total frequency of myopic disorders 9,4%, of hypermetropic disorders 25,3%, both showing great differences between age groups; convergent strabismus 3,9%; amblyopia 2,6% (13/491 children over 3 years old), more frequent among little girls, in those with 1st examination after 4 years old and in those whose parents didn´t complied to the therapy ordered for the child. Specific objectives dealt with visual acuity and ocular refraction. The comparison of automatic refractometry without and with cycloplegy showed that visual acuity testing is often not enough for a correct diagnosis. Eye disorders in the family history proved to be a very important information. Analysis of corresponding data disclosed a lot of relationships among others: 12 pag1.qxp 27-11-2001 18:28 Page 12 Índice Geral 13 Children with a family history of myopic disorders have more frequently a diagnosis of myopic disorders and a negative refraction, a higher rate of quantitative diagnosis/refraction matching concerning myopic disorders. Those children have in general inverse characteristics regarding hypermetropic disorders. Children with a family history of hypermetropic disorders have more frequently a diagnosis of hypermetropic disorders. Children with a family history of strabismus have more frequently a diagnosis of manifest convergent strabismus and all forms of esodeviations. Children with a family history of astigmatism have more frequently a diagnosis of astigmatism. Ophthalmologic profiles are drawn allowing to take into account in a synoptic way a set of visual health parameters. Data on parents' compliance with therapy ordered for the child, and attitudes regarding child's glass wearing, as well as data on child's behaviour in the classroom and learning difficulties were as a rule too few to allow conclusions but still need more studies in the future. Orthoptists and nurses performed in the same study period a screening of visual acuity <0,8 and of ocular motility disorders addressed to children of 1srt degree of public schools (term 2005/2006) in the town of Lisbon. 520 of such children were screened. 101 of them were examined by the author in her medical office; some were refered, the others taken as a control. Regarding visual acuity the predictive value of a negative test was 91% but the predictive value of a positive test was only 67% (33% of false positive results, consequently a too high rate of overreferal). Performed by orthoptists screening quality was inferior in comparison with screening done by nurses. On the whole this screening had not the required quality. A survey on physicians' and nurses' knowledge, attitudes and practices related to pediatric ophthalmologic care was carried out in health centers. Results are discussed, conclusions drawn. Some suggestions are made aiming at a better children's visual health.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2005.
Title from title page screen (viewed on July 5, 2005). Thesis advisor: Ying-Ling Chen. Document formatted into pages ( vi, 86 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 75-82).

When examining the dimensions of the crystalline lens, it is found that some may vary with different types of refractive error. The effects of several of these variations on refractive error are investigated in this thesis. To examine whether lens thickness was significantly different in youth-onset myopes compared with emmetropes, a structural model was developed and tested. No substantial difference was found between the two groups. In both groups of eyes, increased lens thickness was found to contribute significantly to the refractive state of the eye; a thicker lens effectively being a stronger lens. The crystalline lens may play a different role in early adult-onset myopia which develops after normal growth has ceased compared to its role in youth-onset myopia. Cross-sectional data from early adult-onset myopes, youth-onset myopes and emmetropes were evaluated to determine whether lens thickness differed among the refractive error groups. No significant differences were found. However, some early adult-onset myopes and youth-onset myopes were re-evaluated three years after the initial data were collected and a significant increase in mean lens thickness was, found in the group of early adult-onset, myopes. No significant mean lens thickness increase occurred in the group of youth-onset myopes. To evaluate further the contribution of the crystalline lens dimensions to the refractive state of the eye, radii of curvature and. lens thicknesses of a group of anisometropes were examined. Radii were found not to be consistently flatter or steeper in the relatively, more myropic eye compared with the relatively less myopic eye and there was also no significant difference between mean lens thickness of the relatively more myopic eye compared to mean lens thickness of the relatively less, myopic eye. Crystalline lens thickness and radii of curvature were therefore found to play only a minor role in refractive error development, Deeper vitreous chambers and steeper corneal curvatures were found to be the major contributors to myopia.

Age, sex, race, heredity, environment and nutrition have been found to influence ametropia. In this study, the distribution of refractive errors has been investigated in relation to age, sex, race, education and near work, and lighting conditions. Visual awareness and vision screening in pre-school and schoolchildren were also investigated. Data were collected using the Nikon auto-refractor, retinoscope, Snellen V.A chart, and subjective techniques. 777 people were refracted, whose ages ranged between four and eighty years. Measurements were made in different sections of Umlazi township, therefore people of different socio-economic sectors were refracted. Four year-old children were found to be hyperopic. Hyperopia decreased and refraction shifted towards emmetropia. Myopia started to appear at the age of ten. Myopia increased until the age of twenty, and thereafter decreased slowly until the age of thirty three, where the average refraction was emmetropia. From age forty onwards, hyperopia was predominant. The incidence of high astigmatism, high hyperopia and high myopia is low in this community. Most people fall in the spherical refractive error region of between -1.000 and +1.000. The curve is leptokurtotic with highest peak around +0.250. The cylindrical error is between -0.500 and -1.000. No significant difference between sexes was found except at the fourth age group (40-51), where females are more hyperopic than males. The other sex difference is at ages ten to twelve, where females develop myopia earlier than males. Illumination plays no important role in the development of refractive errors in this community. Education and near work seem to account very little to the development of myopia. The influence of heredity on the development of ametropia was not investigated in depth. However, there is no evidence of heredity influencing the development of ametropia. There is a lack of vision screening and visual awareness.
Thesis (M.Optom.)-University of Durban-Westville, 1988.

Dissertação de mestrado em Optometria Avançada
Em Portugal estima-se que 4 milhões de pessoas sofram de problemas visuais (cerca de 40% da população). Este número mostra que se trata de uma questão importante de saúde pública. A inexistência de dados epidemiológicos sobre a prevalência das ametropias é uma lacuna grave na caraterização do problema, torna urgente a realização deste tipo de estudos. O objetivo deste trabalho foi o cálculo da prevalência das ametropias em Portugal Continental e Regiões Autónomas. Através de dois inquéritos recolheu-se a informação sobre a correção refrativa usada. No primeiro inquérito foram analisadas 1035 prescrições optométricas respeitantes a indivíduos com idades entre os 4 e 96 anos. No segundo inquérito foram obtidos, via telefone, os dados do erro refrativo de 652 indivíduos. A partir da primeira amostra obteve-se a prevalências das ametropias nas prescrições optométricas (a presbicia não foi considerada) e da segunda amostra a prevalência do uso da refração para longe na população Portuguesa. A partir destas duas prevalências obteve-se a prevalência das ametropias na população Portuguesa. Estima-se que 1 464 000 portugueses tenham astigmatismo ≥+1,00 D, 220 000 tenham hipermetropia ≥+3,00 D, 1 917 000 tenham miopia ≤-1,00 D e 285 tenham miopia ≤-5,00 D. Este trabalho fornece valores de referência úteis para conhecer a distribuição das ametropias em Portugal. Os erros refrativos afetam aproximadamente um terço da população nacional. A miopia foi a ametropia com maior prevalência, em concordância com estudos anteriores.
It was estimated that 4 million people suffer from visual problems in Portugal (about 40% of the population), this figure shows that is an important matter of public health. The nonexistence of epidemiological data on the prevalence of refractive errors is an important lack of information in public health which leads to the urgent realization of this type of studies. From two surveys there were estimated (1) the prevalence of ametropies in the refractive prescription made by optometrists and (2) the prevalence of subjects wearing glass and contact lens for refractive errors compensation. In the first survey it was enrolled, retrospectively, 1035 subjects, aging from 4 to 96 years. In the second survey 652 subjects, aging from x to y were recruited by sortition from the general population and the survey was conducted by phone calls. The prevalence of refractive errors in the Portuguese population was estimated from the two previously prevalences. It is estimated that astigmatism ≥+1,00 D, hyperopia ≥+3,00 D, myopia ≤-1,00 D and myopia ≤- 5,00 D affect 1464000, 220000, 1917000, 285000 Portuguese people, respectively. This study provides reference values useful to know the distribution of refractive errors in Portugal. Refractive errors affect approximately one third of the national population. Myopia was the most prevalent refractive errors, in agreement with previous studies.

Summary: Evaluation of visual functions after laser correction of ammetropia 1. We evaluated the quality of vision of 55 pacients (110 eyes) with myopia from - 0,5 dpt to -6,00 dpt after laser correction with PRK and LASIK. We compaired the results between group A after laser correction with the excimer laser Esiris (Schwind, Germany) and group B after correction with Amaris (Schwind, Germany). We investigated subjective visual perception, standardized visual acuity and contrast sensitivity under photopic and mesopic conditions as well as glare sensitivity at 1, 3, 12 and 24 months postoperatively. 2. Subjective perception: One month after the procedure, there were significant differences in questions concerning the overall visual quality, while watching TV and driving during the day and at night, with group B patients significantly more satisfied. Twelve months after the procedure, 100% of the patients of both groups were satisfied with their quality of vision. 3. Visual acuity: In group A, photopic and mesopic visual acuity significantly decreased 1 month after the procedure and then increased and differed only insignificantly from the preoperative values. In group B, photopic and mesopic visual acuity was changing insignificantly upto 3 months after the procedure and then increased significantly to...

碩士
國立交通大學
經營管理研究所
92
With the advancement of technology, scientists have a further understanding of laser and know how to control it better. Many medical instruments applying laser technology have been made to diagnose cure diseases. For example, the oculists tried to cure many kinds of eye’s diseases by laser in ophthalmology application. Nowadays, the laser surgery has been one of most popular ophthalmology surgeries. Laser has been the most widely used to permanently correct refractive errors. LASIK is approved to treat ametropia safely and precisely by the strictly clinical tests of FDA in July 1998. LASIK has some advantages over accuracy, safety, stability, timeless and comfort. Furthermore, over 40% of Taiwanese are nearsighted. Many of them are eager to have a better eyesight. Thus, “The laser surgery- LASIK” becomes the new focus by everybody. We used Innovation Adoption Theory and revised it as the study’s frame used to identify the acceptance of the LASIK operation based on ameprotia patients' preference and their demand. In addition, we try to find out whether the ameprotia patients can be segregated by their life style so as to identify target consumer groups and to describe their characteristics. We provide our research results to the industry to formulate their marketing strategies. This research is to use structured questionnaires, and we got 432 effective copies of the samples we used for this study are the ameprotia patients who attended to the 7 medical centers of Taipei. All data were analyzed with the following methods: Frequency Distribution Analysis, Factor Analysis, Reliability Analysis, Cluster Analysis, Discriminant Analysis, MANOVA Analysis, Scheffe’s Test and Chi-square Test. From the samples we discovered that potential consumers could be effectively segregated by life style. In addition, we found the demographic variables shows difference do exist in terms of the gender, age, education, occupation, personal monthly average income and the habit to take the medical treatment. We found the consumers’ adoption behavior variables shows difference do exist in terms of source of information, opinion of the function, interested, reason to adopt, the price of the operation and the place to adopt. In order to target these potential customers, different marketing strategies are required. Primary sources of the LASIK information come from TV and radio programs, the next is from samples’ relatives and friends. About 60% of the samples who has heard of LASIK can provide multifunctional services when compared to RK, ALK/MLK and PRK. 90% of the samples showed interests in LASIK. About 83% of the samples who want to adopt LASIK because they can exempt from wearing glasses or contact lenses. Most of the samples can accept the price of LASIK about 20 to 40 thousands. The majority are willing to take LASIK in medical centers and the next are in ophthalmology clinics. It also shows differences do exist between different lifestyle groups in evaluating factors on attach importance to medical treatment mechanisms, reputation, time, convenience to see a doctor and price. In the whole potential users, they emphasize to the convenience to see a doctor and the additional value of the operation.

A troca do cristalino com finalidade refractiva consiste na realização da cirurgia, pela técnica de facoemulsificação por uma pequena incisão, e implante de lente intra-ocular (LIO) com a finalidade de correção de ametropias. A correcção de grandes ametropias esféricas através do implante de LIO mudou nos últimos anos. A técnica cirúrgica da facoemulsificação, tem como vantagem a redução do tempo cirúrgico e da frequência de complicações, aumento da previsibilidade refractiva, desenvolvimento de novas tecnologias de biometria e fórmulas de cálculo e incremento da qualidade e versatilidade das lentes intraoculares. Nas últimas duas décadas ocorreu um grande desenvolvimento das tecnologias na área da cirurgia refractiva, com aprimoramento dos aparelhos e softwares de ablação pelo Excimer laser, otimizando os resultados quanto à acuidade e qualidade visual nas cirurgias ablativas corneanas. A cirurgia refractiva pelo Excimer laser tornou-se procedimento corrente no meio oftalmológico na correcção de miopias leves a moderadas, astigmatismos e hipermetropias leves, com resultados confiáveis e reprodutiveis. Porém, a correcção de altas ametropias esféricas e da presbiopia é ainda um desafio para o Excimer, pois nestas condições a cirurgia ablativa corneana não oferece bons resultados, no que diz respeito à estabilidade refracional e segurança (risco de ectasias, alteração da biomecânica da córnea, indução de aberrações). Tais limitações do Excimer vieram de encontro com a evolução das técnicas de facoemulsificação e das LIO, portanto, pacientes com altas miopias, hipermetropias moderadas a altas e presbiopia seriam melhores candidatos às técnicas intra-oculares de correção refractiva: implante de lentes fáquicas ou substituição do cristalino por Lio com finalidade refractiva. O objetivo deste relatório clínico foi estudar um caso de hipermetropia elevada com a técnica cirúrgica de facoemulsificação e posterior LASIK considerando as suas vantagens, tendo em conta o alto valor refractivo.

Yes
Background: The importance of optimal and/or superior vision for participation in high-level sport remains the subject of considerable clinical research interest. Here we examine the vision and visual history of elite/near-elite cricketers and rugby-league players. Methods: Stereoacuity (TNO), colour vision, and distance (with/without pinhole) and near visual acuity (VA) were measured in two cricket squads (elite/international-level, female, n=16; near-elite, male, n=23) and one professional rugby-league squad (male, n=20). Refractive error was determined, and details of any correction worn and visual history were recorded. Results: Overall, 63% had their last eye-examination within 2 years. However, some had not had an eye examination for 5 years, or had never had one (near-elite-cricketers: 30%; rugby-league players: 15%; elite-cricketers: 6%). Comparing our results for all participants to published data for young, optimally-corrected, non-sporting adults, distance VA was ~1 line of letters worse than expected. Adopting α=0.01, the deficit in distance-VA deficit was significant, but only for elite-cricketers (p<0.001) (near-elite cricketers, p=0.02; rugby-league players, p=0.03). Near-VA did not differ between subgroups or relative to published norms for young adults (p>0.02 for all comparisons). On average, stereoacuity was better than in young adults, but only in elite-cricketers (p<0.001; p=0.03, near-elite-cricketers; p=0.47, rugby-league -players). On-field visual issues were present in 27% of participants, and mostly (in 75% of cases) comprised uncorrected ametropia. Some cricketers (near-elite: 17.4%; elite: 38%) wore refractive correction during play but no rugby-league player did. Some individuals with prescribed correction choose not to wear it when playing. Conclusion: Aside from near stereoacuity in elite-cricketers, these basic visual abilities were not better than equivalent, published data for optimally-corrected adults. 20-25% exhibited sub-optimal vision, suggesting that the clearest possible vision might not be critical for participation at the highest levels in the sports of cricket or rugby-league. Although vision could be improved in a sizeable proportion of our sample, the impact of correcting these, mostly subtle, refractive anomalies on playing performance is unknown.
Funded by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC) grants BB/J018163/1, BB/J016365/1 and BB/J018872/1.