Thesis (M. Med. Sc.)--University of Hong Kong, 2004. / Also available in print.

Thesis (doctoral)--University of Lund.

Thesis (doctoral)--Freie Universität Berlin, 1980.

Thesis (doctoral)--University of Lund.

Silicone oil (SO) is widely used as the long-term intraocular tamponade in treating various eye diseases such as complicated retinal detachment, proliferative vitreoretinopathy, proliferative diabetic retinopathy, giant retinal tear and ocular trauma. However, its propensity to emulsify is an inherent problem of its long-term use in-vivo. Dispersal of SO into many tiny oil droplets causes numerous complications such as inflammation, glaucoma and reproliferation. It may also be responsible for possible toxicity to both retina and optic nerve. Emulsification is one of the problems associated to the use of SO as a long-term intraocular tamponade. This study focused on the understanding on the physical nature and formation of in-vivo SO emulsion and the development of methods to reduce the complications associated with emulsification of SO by engineering approaches. A stepper motor driven mechanical platform was built to study the fluid flow of SO within an eye model chamber during eye-like movements and a quantitative method was established to study SO emulsification, both in-vivo and in-vitro. This method was used to compare the relative resistance of different SO against emulsification. In the last part of the thesis a novel rinse was proposed which aimed at removing the emulsified SO droplets in-vivo in an effective way. In the dynamic eye model experiment, both the increase in shear viscosity of SO and the extent of SO fill had an effect in reducing the shear. These effects were small compared to the effect of indents at reducing shear rate during eye-like movements. When SO emulsions from patients were analyzed it was found that over 90% of the emulsified droplets were outside the observable range under slit-lamp biomicroscopy. When the emulsification resistance of SO was tested using the quantitative method the result confirmed that SO with high-molecular-weight component (HMWC) was more emulsification resistant than SO with the same shear viscosity. The addition of HMWC increases the elasticity and thus increasing its resistance against emulsification. A novel rinse was also proposed to remove the emulsified droplets using physical phenomenon of double emulsification. To conclude, this study improved the understanding of the formation of SO emulsification. The clinical observable emulsified droplets are probably in all cases that was just the tip of the iceberg. Three practical suggestions were made: Firstly, the use of SO and encircling scleral buckling procedure in combination might reduce the shear rate. Secondly, the use of HMWC can reduce emulsification. Lastly, there may be a role in rinsing out the emulsified droplets using the proposed novel solution. The novel solution is going to fully developed and commercialized in the near future. / published_or_final_version / Ophthalmology / Doctoral / Doctor of Philosophy

However, this is by no means the limit. More knowledge on macular hole is needed. Continuous research in Hong Kong and other scientific communities are indispensable. A multicentre, multi-surgeon study should be contemplated and carried out prior to the generalization or application of this technique to all patients. / Over the last few years, we have collected essential clinical and laboratory data on indocyanine green (ICG) assisted internal limiting membrane (ILM) peeling in macular hole surgery in Hong Kong. With the intraoperative use of a small volume and low concentration of ICG, we have shown the usefulness and safety of this technique in improving the surgical outcomes, both antomically and functionally, in patients with macular hole of idiopathic type or in severely myopic eyes. Our randomized controlled trial demonstrated higher anatomical closure rate and better visual outcome with ICG assisted ILM peeling compared with no ILM peeling in primary idiopathic macular hole surgery. Our case-control study also demonstrated that ICG assisted ILM removal in macular hole surgery of severely myopic eyes gives promising anatomical closure rate and visual outcome comparable to emmetropic ones. / Kwok Kwan-ho. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 201-214). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Orientadores: Nelci Fenalti Höehr, Marcos Nogueira Eberlin / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T10:40:41Z (GMT). No. of bitstreams: 1 SantosJunior_JulioCesar_M.pdf: 4092105 bytes, checksum: 8809a688f7411f1a87fd956c6674fe41 (MD5) Previous issue date: 2014 / Resumo: Embora as anfetaminas estejam proibidas no Brasil, elas continuam sendo adquiridas ilegalmente assim como os canabinóides e cocaína, que representam um dos principais problemas de saúde pública a serem enfrentados no nosso país. Um dos grandes desafios desta área é a dificuldade de obtenção de material para exames periciais. O humor vítreo por encontrar-se isolado em um compartimento relativamente protegido de contaminação externa, invasão de microorganismos e traumatismos em geral, bem como por sua simplicidade/estabilidade analítica e esterilidade durante um longo período após a morte constitui-se como uma excelente amostra para a determinação de xenobióticos em corpos politraumatizados, carbonizados ou em decomposição, auxiliando na delegação da causa mortis. O uso da espectrometria de massas e o advento de novas metodologias de ionização são ferramentas essenciais à toxicologia forense, a V-EASI (venture easy ambient sonic-spray), é uma fonte de ionização de fácil aplicação e instalação, que não requer fluxo de eluente e os demais fatores utilizados nas fontes comerciais. Além disso, o uso da espectrometria de massas de ressonância ciclotrônica de íons por transformada de Fourier (FT-ICR-MS) de ultra-alta resolução e exatidão (valores de m/z exatos) leva a exata composição molecular, alcançando erros abaixo de 1 ppm (partes-por-milhão). Perante isso a avaliação da fórmula molecular normalmente é inequívoca. Quando acoplada a ionização por eletrospray (ESI) espécies moleculares suaves são formadas reduzindo a complexidade do espectro e produzindo informação composicional livre de fragmentos em misturas complexas facilitando sua compreensão. Portanto este trabalho visa o desenvolvimento de metodologias analíticas para análise de drogas de abuso presentes em humor vítreo, empregando o uso de técnicas modernas de espectrometria de massas (FT-ICR-MS e V-EASI-MS) / Abstract: Although amphetamines are banned in Brazil, they remain illegally acquired as cannabinoids and cocaine, which account for a public health task to be faced in this country. The major challenge is to obtain material for investigation exams. The vitreous humor constitutes a good alternative for these exams, since it occurs isolated in a protected space, free of external contamination and of microorganisms and traumatisms, and also due to its analytical stability and sterility preserving it for a long period after death. Moreover, the vitreous humor constitutes an excellent sample for the determination of xenobiotics even in polytraumatized bodies, carbonized or in decomposition, involved in the causa mortis. The use of mass spectrometry and the advent of new ionization methods are essential tools for forensic toxicology, the V-EASI (venture easy ambient sonic-spray), is a source of ionization easy to use and install, not requiring nitrogen flow, eluent flow and other factors used in commercial sources. Furthermore, the use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) provides ultra high resolution and accuracy in mass analysis and its accurate m/z values lead to the exact molecular composition, reaching errors below 1 ppm (parts-per-million) on normal operational conditions, the assigned molecular formula are normally unequivocal. When electrospray ionization (ESI) is used, soft molecular species are formed reducing spectra complexity and providing fragment-free compositional information about complex mixtures facilitating comprehension. Therefore, this work aims at the development of analytical methodologies for the analysis of drugs of abuse present in the vitreous humor, employing the use of modern techniques of mass spectrometry (FT-ICR-MS and V-EASI-MS / Mestrado / Ciencias Biomedicas / Mestre em Ciências Médicas

Orientador: Keila Miriam Monteiro de Carvalho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T15:10:56Z (GMT). No. of bitstreams: 1 Carvalho_FelipedoCarmo_M.pdf: 1885635 bytes, checksum: 587e00582d2fc8592a6675ab20a7e71c (MD5) Previous issue date: 2008 / Resumo: Introdução: O tratamento cirúrgico das doenças retinianas sofreu grandes mudanças nas últimas décadas. Na vitrectomia posterior via pars plana (VVPP) realizada com o sistema 20 gauge são utilizados instrumentos com 0.9 mm de diâmetro. Em 2002 foi proposto um novo sistema de vitrectomia posterior composto por instrumentos de 0.5 mm de diâmetro denominado sistema 25 gauge. Objetivo: O objetivo desse estudo é comparar os aspectos per e pós-operatórios das VVPP realizadas com os sistemas 20 e 25 gauge. Metodologia: Foram selecionados prospectivamente pacientes com indicação de vitrectomia apresentando as seguintes doenças retinianas: Buraco Macular idiopático (26 casos), Membrana Epiretiniana Idiopática (28 casos) e Hemorragia Vítrea secundária à Retinopatia Diabética (26 casos), totalizando 80 olhos de 79 pacientes. Após o exame pré-operatório inicial, os pacientes foram distribuídos aleatoriamente e igualitariamente em 2 grupos de acordo com a doença retiniana. O primeiro grupo foi submetido a VVPP com o sistema 20 gauge, enquanto o segundo grupo foi submetido a VVPP com o sistema 25 gauge . Os parâmetros analisados nos dois grupos foram: pressão intra-ocular, tempo cirúrgico, queixa do paciente no pós-operatório através de questionário objetivo sobre dor ocular, desconforto ocular, lacrimejamento, fotofobia e hiperemia ocular, e complicações per e pós-operatórias. O seguimento dos pacientes foi de 6 meses. Resultados: Em relação à presença de queixas pós-operatórias houve diferença entre as seguintes variáveis: dor (p= 0,008), hiperemia ocular (p = 0,014) e lacrimejamento (p= 0,034), com maior queixa para os pacientes submetidos à cirurgia com o sistema 20 gauge. A cirurgia com o sistema 20 gauge ocorreu em um tempo médio de procedimento igual a 39,3 (± 5,4) min enquanto a cirurgia com o sistema 25 gauge ocorreu em um tempo médio de procedimento igual a 23,7 (±7,9) min (p<0,001). Não houve diferença significativa da média da PIO em relação ao tipo de cirurgia realizada e o período de observação. Foram observados 3 casos de formação de bolha conjuntival no per operatório e um caso de endoftalmite no pós-operatório em pacientes submetidos ao sistema 25 gauge. Conclusão: Não foram observadas diferenças estatísticas entre as médias da PIO e o índice de complicações per e pós-operatório sendo o procedimento com o sistema 25 gauge realizado em menor tempo cirúrgico e oferecido maior conforto aos pacientes no pós-operatório / Abstract: Introduction: In the last decades, great improvement has been achieved on the surgical treatment of retinal disease using smaller diameter instruments. Nowadays, pars plana vitrectomy (PPV) is usually executed using the 20 gauge system, in which the instrument's diameter is 0,9mm. In 2002, a new posterior victrectomy system was proposed, using 25 gauge (0,5mm) diameter instruments. Purpose: To compare intra and post operative parameters of the PPV technique with 20 and 25 gauge. Methods: Patients presenting retinal disease, including idiopathic macular hole (26 cases), idiopathic epiretinal membrane (28 cases), and vitreous hemorrhage due to diabetic retinopathy (26 cases) with PPV indication were selected, with a total of 80 patients. After the initial evaluation, patients were randomly assigned to one of the two groups, according to the retinal disease. The first group was submitted to the 20 gauge system surgery and the second group, to the 25 gauge technique. Parameters observed were: intraocular pressure (IOP), surgery time, patients¿ complains on post surgical days through an objective questionnaire about ocular pain, ocular discomfort, tearing, photophobia, ocular redness and intra and post-operative complications. The follow-up of these patients was 6 months. Results: On post operative complains, difference was observed on the following parameters: ocular pain (p= 0,008), ocular redness (p= 0,014) and tearing (p= 0,034), with greatest complains between patients of the 20 gauge group. Median surgery time of the 20 gauge surgery was 39,3 (± 5,4) min; the 25 gauge system was executed in about 23,7 (± 7,9) min (p < 0,001). No significant differences were observed on median post-operative IOP measurements. Bubble conjuntival formation was observed in 3 cases in 25 gauge system. Endophthalmitis was observed in one case in the the group of 25 gauge system. Conclusion: The surgical procedures are equivalent when comparing the median intraocular pressure and the intra and post operative complications, but the 25 gauge system has the advantage of being less time consuming and offering the patient more comfort during the post operative period / Mestrado / Oftalmologia / Mestre em Ciências Médicas

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 4 uppsatser.