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Although experiential prescribing maxims are quoted in some optometric textbooks their content varies significantly and no direct research evidence was available to support their use. Accordingly in chapters 2 and 3, the uses of several potential prescribing rules were investigated in the UK optometric profession. Our results indicated that the subjective refraction result exerted a strong hold on the prescribing outcome with 40-85% of optometrists prescribing the subjective result in a variety of scenarios. The finding that after 40 years qualified, experienced optometrists were three times more likely to suggest a partial prescription was an important discovery that provides significant support for the prescribing rules suggested by various authors. It would also appear from the results of the retrospective evaluation of the 'if it ain't broke, don't fix it' clinical maxim in Chapter 4 that spectacle dissatisfaction rates could be reduced by between 22 to 42% depending on how strictly the maxim is interpreted by the practitioner. Certainly an 'if it ain't broke, don't fix it much' maxim was suggested as being particularly appropriate. Chapter 5 included a reanalysis of previously published data that found no change in falls rate after cataract surgery to investigate any influence of refractive correction change and /or visual acuity change on falls rate. Unfortunately these data were not sufficiently powered to provide significant results. In chapter 6, a spectacle adaptation questionnaire (SAQ) was developed and validated using Rasch analysis. Initial studies found no differences in SAQ with gender or age.

Although experiential prescribing maxims are quoted in some optometric textbooks their content varies significantly and no direct research evidence was available to support their use. Accordingly in chapters 2 and 3, the uses of several potential prescribing rules were investigated in the UK optometric profession. Our results indicated that the subjective refraction result exerted a strong hold on the prescribing outcome with 40-85% of optometrists prescribing the subjective result in a variety of scenarios. The finding that after 40 years qualified, experienced optometrists were three times more likely to suggest a partial prescription was an important discovery that provides significant support for the prescribing rules suggested by various authors. It would also appear from the results of the retrospective evaluation of the ¿if it ain¿t broke, don¿t fix it¿ clinical maxim in Chapter 4 that spectacle dissatisfaction rates could be reduced by between 22 to 42% depending on how strictly the maxim is interpreted by the practitioner. Certainly an ¿if it ain¿t broke, don¿t fix it much¿ maxim was suggested as being particularly appropriate. Chapter 5 included a reanalysis of previously published data that found no change in falls rate after cataract surgery to investigate any influence of refractive correction change and /or visual acuity change on falls rate. Unfortunately these data were not sufficiently powered to provide significant results. In chapter 6, a spectacle adaptation questionnaire (SAQ) was developed and validated using Rasch analysis. Initial studies found no differences in SAQ with gender or age. / College of Optometrists

No / Purpose:¿ A follow up study to investigate whether UK optometrists partially prescribe significant changes in refractive correction to assist patient adaption and whether various aspects of practitioner profiles are linked to the nature of these prescribing decisions. Method:¿ A case scenario type questionnaire was distributed by post and via the internet to UK optometrists. Five case scenarios were described that included information on patient age, symptoms, habitual refractive correction (if any), subjective refraction and any other relevant clinical information. In each case respondents were asked to indicate and justify what refractive correction they would prescribe. Results:¿ A total of 592 questionnaires were completed. Between 41% and 84% prescribed the subjective refraction result depending on the scenario. The likelihood of partial prescribing increased by 34% for every 10 years following qualification and thus after a typical 40 year career, respondents were now over three times more likely to partially prescribe. There were no other links with the propensity to partially prescribe. Conclusion:¿ The subjective refraction result exerted a strong hold on the reported prescribing outcome, particularly for newly qualified optometrists. Partial prescribing was increasingly proposed the greater the number of years the respondent had been qualified. This suggests that with increasing exposure to patients who return dissatisfied with their spectacles, a greater appreciation of partial prescribing is gained. This link seems to be an important finding that provides significant support for the prescribing rules suggested by textbooks, which are not yet supported by research evidence.

Esta tese descreve métodos interativos para estimar e compensar erros de refração (NETRA) e opacidades ópticas (CATRA) em sistemas de imageamento usando telas de campos de luz programáveis, de alta resolução e alto contraste. Os novos métodos para oftalmologia computacional descritos aqui podem avaliar câmeras e olhos se o usuário do sistema estiver consciente do modelo de interação. A solução combina elementos ópticos baratos, interfaces interativas e reconstrução computacional. Uma tela de campos de luz, posicionada perto do olho, cria objetos virtuais em profundidades pré-definidas através de várias seções do olho. Via esta plataforma, cria-se uma nova gama de aplicações interativas que é extremamente sensível a aberrações ópticas. A capacidade de focar em um objeto virtual, alinhar padrões exibidos na tela e detectar suas variações de forma e brilho permite ao sistema estimar a função de propagação de ponto de luz para o olho e a acomodação da lente. Enquanto os sistemas convencionais requerem formação especializada, dispositivos caros, procedimentos de segurança sensíveis e normalmente não são móveis, esta tese simplifica o mecanismo, colocando o paciente no centro do teste. Ao final, a resposta do usuário calcula a condição de refração em termos de poderes esférico e cilíndrico, o eixo de astigmatismo, o poder de acomodação da lente e mapas para a opacidade, atenuação, contraste e função de espalhamento de um ponto de luz. O objetivo é permitir que o público em geral opere um sistema de iluminação portátil e obtenha uma compreensão de suas próprias condições visuais. Esta tese apresenta projetos ópticos para software e hardware para oftalmologia computacional. Avaliações com usuários e com câmeras com lentes modificadas são realizadas. Os dados compilados são usados para reconstruir visão afetada do indivíduo, oferecendo uma nova abordagem para capturar informações para o rastreio, diagnóstico e análises clínicas de anomalias visuais. / This thesis proposes light-field pre-warping methods for measuring and compensating for optical aberrations in focal imaging systems. Interactive methods estimate refractive conditions (NETRA) and model lens opacities (CATRA) of interaction-aware eyes and cameras using cost-efficient hardware apps for high-resolution screens. Tailored displays use stereo-viewing hardware to compensate for the measured visual aberrations and display in-focus information that avoids the need of corrective eyeglasses. A light-field display, positioned very close to the eye, creates virtual objects in a wide range of predefined depths through different sectors of the eye’s aperture. This platform creates a new range of interactivity that is extremely sensitive to spatially-distributed optical aberrations. The ability to focus on virtual objects, interactively align displayed patterns, and detect variations in shape and brightness allows the estimation of the eye’s point spread function and its lens’ accommodation range. While conventional systems require specialized training, costly devices, strict security procedures, and are usually not mobile, this thesis simplifies the mechanism by putting the human subject in the loop. Captured data is transformed into refractive conditions in terms of spherical and cylindrical powers, axis of astigmatism, focal range and aperture maps for opacity, attenuation, contrast and sub-aperture point-spread functions. These optical widgets carefully designed to interactive interfaces plus computational analysis and reconstruction establish the field of computational ophthalmology. The overall goal is to allow a general audience to operate portable light-field displays to gain a meaningful understanding of their own visual conditions. Ubiquitous, updated, and accurate diagnostic records can make private and public displays show information in a resolution that goes beyond the viewer’s visual acuity. The new display technology is able to compensate for refractive errors and avoid light-scattering paths. Tailored Displays free the viewer from needing wearable optical corrections when looking at it, expanding the notion of glasses-free multi-focus displays to add individual variabilities. This thesis includes proof-of-concept designs for ophthalmatic devices and tailored displays. User evaluations and validations with modified camera optics are performed. Capturing the daily variabilities of an individual’s sensory system is expected to unleash a new era of high-quality tailored consumer devices.

Esta tese descreve métodos interativos para estimar e compensar erros de refração (NETRA) e opacidades ópticas (CATRA) em sistemas de imageamento usando telas de campos de luz programáveis, de alta resolução e alto contraste. Os novos métodos para oftalmologia computacional descritos aqui podem avaliar câmeras e olhos se o usuário do sistema estiver consciente do modelo de interação. A solução combina elementos ópticos baratos, interfaces interativas e reconstrução computacional. Uma tela de campos de luz, posicionada perto do olho, cria objetos virtuais em profundidades pré-definidas através de várias seções do olho. Via esta plataforma, cria-se uma nova gama de aplicações interativas que é extremamente sensível a aberrações ópticas. A capacidade de focar em um objeto virtual, alinhar padrões exibidos na tela e detectar suas variações de forma e brilho permite ao sistema estimar a função de propagação de ponto de luz para o olho e a acomodação da lente. Enquanto os sistemas convencionais requerem formação especializada, dispositivos caros, procedimentos de segurança sensíveis e normalmente não são móveis, esta tese simplifica o mecanismo, colocando o paciente no centro do teste. Ao final, a resposta do usuário calcula a condição de refração em termos de poderes esférico e cilíndrico, o eixo de astigmatismo, o poder de acomodação da lente e mapas para a opacidade, atenuação, contraste e função de espalhamento de um ponto de luz. O objetivo é permitir que o público em geral opere um sistema de iluminação portátil e obtenha uma compreensão de suas próprias condições visuais. Esta tese apresenta projetos ópticos para software e hardware para oftalmologia computacional. Avaliações com usuários e com câmeras com lentes modificadas são realizadas. Os dados compilados são usados para reconstruir visão afetada do indivíduo, oferecendo uma nova abordagem para capturar informações para o rastreio, diagnóstico e análises clínicas de anomalias visuais. / This thesis proposes light-field pre-warping methods for measuring and compensating for optical aberrations in focal imaging systems. Interactive methods estimate refractive conditions (NETRA) and model lens opacities (CATRA) of interaction-aware eyes and cameras using cost-efficient hardware apps for high-resolution screens. Tailored displays use stereo-viewing hardware to compensate for the measured visual aberrations and display in-focus information that avoids the need of corrective eyeglasses. A light-field display, positioned very close to the eye, creates virtual objects in a wide range of predefined depths through different sectors of the eye’s aperture. This platform creates a new range of interactivity that is extremely sensitive to spatially-distributed optical aberrations. The ability to focus on virtual objects, interactively align displayed patterns, and detect variations in shape and brightness allows the estimation of the eye’s point spread function and its lens’ accommodation range. While conventional systems require specialized training, costly devices, strict security procedures, and are usually not mobile, this thesis simplifies the mechanism by putting the human subject in the loop. Captured data is transformed into refractive conditions in terms of spherical and cylindrical powers, axis of astigmatism, focal range and aperture maps for opacity, attenuation, contrast and sub-aperture point-spread functions. These optical widgets carefully designed to interactive interfaces plus computational analysis and reconstruction establish the field of computational ophthalmology. The overall goal is to allow a general audience to operate portable light-field displays to gain a meaningful understanding of their own visual conditions. Ubiquitous, updated, and accurate diagnostic records can make private and public displays show information in a resolution that goes beyond the viewer’s visual acuity. The new display technology is able to compensate for refractive errors and avoid light-scattering paths. Tailored Displays free the viewer from needing wearable optical corrections when looking at it, expanding the notion of glasses-free multi-focus displays to add individual variabilities. This thesis includes proof-of-concept designs for ophthalmatic devices and tailored displays. User evaluations and validations with modified camera optics are performed. Capturing the daily variabilities of an individual’s sensory system is expected to unleash a new era of high-quality tailored consumer devices.

Esta tese descreve métodos interativos para estimar e compensar erros de refração (NETRA) e opacidades ópticas (CATRA) em sistemas de imageamento usando telas de campos de luz programáveis, de alta resolução e alto contraste. Os novos métodos para oftalmologia computacional descritos aqui podem avaliar câmeras e olhos se o usuário do sistema estiver consciente do modelo de interação. A solução combina elementos ópticos baratos, interfaces interativas e reconstrução computacional. Uma tela de campos de luz, posicionada perto do olho, cria objetos virtuais em profundidades pré-definidas através de várias seções do olho. Via esta plataforma, cria-se uma nova gama de aplicações interativas que é extremamente sensível a aberrações ópticas. A capacidade de focar em um objeto virtual, alinhar padrões exibidos na tela e detectar suas variações de forma e brilho permite ao sistema estimar a função de propagação de ponto de luz para o olho e a acomodação da lente. Enquanto os sistemas convencionais requerem formação especializada, dispositivos caros, procedimentos de segurança sensíveis e normalmente não são móveis, esta tese simplifica o mecanismo, colocando o paciente no centro do teste. Ao final, a resposta do usuário calcula a condição de refração em termos de poderes esférico e cilíndrico, o eixo de astigmatismo, o poder de acomodação da lente e mapas para a opacidade, atenuação, contraste e função de espalhamento de um ponto de luz. O objetivo é permitir que o público em geral opere um sistema de iluminação portátil e obtenha uma compreensão de suas próprias condições visuais. Esta tese apresenta projetos ópticos para software e hardware para oftalmologia computacional. Avaliações com usuários e com câmeras com lentes modificadas são realizadas. Os dados compilados são usados para reconstruir visão afetada do indivíduo, oferecendo uma nova abordagem para capturar informações para o rastreio, diagnóstico e análises clínicas de anomalias visuais. / This thesis proposes light-field pre-warping methods for measuring and compensating for optical aberrations in focal imaging systems. Interactive methods estimate refractive conditions (NETRA) and model lens opacities (CATRA) of interaction-aware eyes and cameras using cost-efficient hardware apps for high-resolution screens. Tailored displays use stereo-viewing hardware to compensate for the measured visual aberrations and display in-focus information that avoids the need of corrective eyeglasses. A light-field display, positioned very close to the eye, creates virtual objects in a wide range of predefined depths through different sectors of the eye’s aperture. This platform creates a new range of interactivity that is extremely sensitive to spatially-distributed optical aberrations. The ability to focus on virtual objects, interactively align displayed patterns, and detect variations in shape and brightness allows the estimation of the eye’s point spread function and its lens’ accommodation range. While conventional systems require specialized training, costly devices, strict security procedures, and are usually not mobile, this thesis simplifies the mechanism by putting the human subject in the loop. Captured data is transformed into refractive conditions in terms of spherical and cylindrical powers, axis of astigmatism, focal range and aperture maps for opacity, attenuation, contrast and sub-aperture point-spread functions. These optical widgets carefully designed to interactive interfaces plus computational analysis and reconstruction establish the field of computational ophthalmology. The overall goal is to allow a general audience to operate portable light-field displays to gain a meaningful understanding of their own visual conditions. Ubiquitous, updated, and accurate diagnostic records can make private and public displays show information in a resolution that goes beyond the viewer’s visual acuity. The new display technology is able to compensate for refractive errors and avoid light-scattering paths. Tailored Displays free the viewer from needing wearable optical corrections when looking at it, expanding the notion of glasses-free multi-focus displays to add individual variabilities. This thesis includes proof-of-concept designs for ophthalmatic devices and tailored displays. User evaluations and validations with modified camera optics are performed. Capturing the daily variabilities of an individual’s sensory system is expected to unleash a new era of high-quality tailored consumer devices.