Nichtglaukomatöse Optikusatrophien führen nicht nur zu einer Verminderung der Dicke der retinalen Nervenfaserschicht (RNFL) sondern auch zu einer Reduktion des Makulavolumens. In dieser Arbeit wurde mit Hilfe der optischen Kohärenztomographie (OCT) untersucht, welche Schichten der Makula von Dickenveränderungen als Folge einer Optikusatrophie betroffen sind. Es wurden 27 Patienten mit nichtglaukomatösen Optikusatrophien unterschiedlicher Ätiologie (postneuritische, hereditäre und traumatische Atrophien) und 21 augengesunde Kontrollpersonen untersucht. OCT-Scans der RNFL und der Makula wurden mit Hilfe des Stratus OCT 3000 (Carl Zeiss Meditec) durchgeführt. Die axialen Reflektivitätsprofile der radialen Scans wurden aus den exportierten JPEG-Bildern an zwölf Punkten in je 1,5mm Entfernung von der Foveola vermessen und gemittelt. Das charakteristische Reflektivitätsprofil mit fünf Intensitätsmaxima und vier Intensitätsminima wurde der Lokalisation der einzelnen Makulaschichten zugeordnet. Die von nichtglaukomatöser Optikusatrophie betroffenen Augen wiesen im Vergleich zu den Augen der augengesunden Normalpersonen signifikant (p<0,05) reduzierte RNFL-Dicken (um 35,5% reduziert) und Makulavolumen-Werte (um 11,8% reduziert) auf. Bei allen untersuchten Formen der Optikusatrophie waren nicht nur die makuläre Nervenfaserschicht (MNFL) sondern alle inneren Schichten der Makula verdünnt. Die mittlere Reduktion betrug 21,2% für die MNFL, 39,7% für die Ganglienzellschicht, 33,2% für die innere plexiforme Schicht und 9,4% für die innere Körnerzellschicht im Vergleich zu den Werten der Normalpersonen. Veränderungen der äußeren Netzhautschichten traten nur bei den posttraumatischen Atrophien auf. Eine Beurteilung der Dicke aller einzelnen Netzhautschichten aus OCT-Scans ist mit Hilfe geräteintegrierter Software bisher noch nicht möglich. Die quantitative Analyse der axialen Reflektivitätsprofile aus exportierten OCT-Bildern stellt eine geeignete Methode zur Beschreibung des Verlaufs und der Lokalisation von Makulaveränderungen bei Optikusatrophien verschiedener Genese dar.

The early non-invasive diagnosis of epithelial tissue alterations in daily clinical routine is still challenging. Since optical coherence tomography (OCT) shows the potential to differentiate between benign and malignant tissue of primal endothelium, OCT could be beneficial for the early diagnosis of malignancies in routine health checks. In this research, a new handheld endoscopic scanning unit was designed and connected to a spectral domain OCT system of our workgroup for the in vivo imaging of the human oral mucosa.

[pt] Foram desenvolvidas fontes ópticas para obtenção de imagens por tomografia de coerência óptica com alta resolução. Dois tipos de abordagens foram realizados, uma com um laser contínuo sintonizável, que neste trabalho foi instrumentado com marcadores de frequência óptica, outra com uma fonte óptica pulsada de banda larga. Mediante um processo de calibricação desenvolvido neste trabalho, a fonte contínua forneceu resoluções de 8 μm e alcances até 0,5 mm, enquanto que a fonte pulsada forneceu resoluções de 3 μm e alcances de 300 μm. A fonte pulsada permitiu ainda a obtenção de imagens em tempo real com capacidade de captura de movimento do objeto. / [en] Optical sources to obtain images through high resolution optical coherence tomography were developed. Two approaches were taken, one with a continuously tunable external cavity laser which, in this work, was modified to produce optical frequency markers, the other with an ultra-wideband pulsed source. Using a calibration process we developed in this work the continuously tunable source continued to achieve resolutions 8 μm and ranges of 0.5 mm, while the pulsed source achieved resolutions of 3.3 μm and ranges of 300 μm. The pulsed source has the capacity to capture real time images.

Glaucoma is the second leading cause of blindness in the world. The disease is characterized by irreversible damage to retinal ganglion cells. Once glaucoma is detected, further vision loss can be prevented by pharmacological or surgical treatment. However, current diagnostic methods lack the necessary sensitivity and up to 40% of vision maybe irreversibly lost before detection occurs. A Swept Source Polarization-Sensitive Optical Coherence Tomography (SS-PSOCT) instrument for high sensitivity cross-sectional imaging of optical anisotropy in turbid media has been designed, constructed, and verified. A multiple-state nonlinear fitting algorithm was used to measure birefringence of the retinal nerve fiber layer with less than 1%± average uncertainty. To perform eye imaging efficiently a slit-lamp based interface for the SS-PSOCT instrument with a Line Scanning Laser Ophthalmoscope (LSLO) was used. This interface allowed for repeatable, stable, and registered measurements of the retina. A fixation target was used to stabilize the volunteer’s eye and image desired areas of the retina. The LSLO allowed for an optimization of the location of OCT scans on the retina and provided a fundus blood vessel signature for registration between different imaging sessions. The SS-PSOCT system was used to measure depth-resolved thickness, birefringence, phase retardation and optic axis orientation of the retinal nerve fiber layer in normal volunteers. The peripapillary area around the optic nerve head (ONH) is most sensitive to glaucoma changes and hence data was acquired as concentric ring scans about the ONH with increasing diameters from 2mm to 5mm. Imaging of normal patients showed that higher values of phase retardation occurred superior and inferior to the optic nerve head especially next to blood vessels and thicker parts of the retinal nerve fiber layer. / text

Accommodation is the change in the dioptric power of the eye altering the focus from distance to near. Presbyopia is the loss of accommodative function that occurs with age. There are many techniques used to measure accommodation, however, there is little consensus as to how clinical data should be collected and analysed. The overarching theme of this thesis is the in vivo examination of accommodation and how lifestyle can affect the onset of presbyopia. An open-field autorefractor with badal adaption was used to examine accommodative dynamic profiles under varying demands of vergence. From this data a new metric for assessing the time for accommodative change was derived. Furthermore this thesis describes a bespoke automated accommodative facility instrument that was developed to provide further assessment of accommodative speeds. Defocus curves are used for assessing accommodation and depth-of-focus; the work presented explores the use of non-linear regression models to define the most appropriate method of assessing defocus curves in phakic subjects, and pseudophakic subjects implanted with an extended depth-of-focus intraocular lens. Using an absolute cut-off criteria of +0.30logMAR improved the repeatability and reliability of the depth-of-focus metrics over a cut-off criteria relative to the best corrected visual acuity. A swept-source anterior segment optical coherence tomographer (AS-OCT) was used to image the morphology of the ciliary muscle during accommodation. The accuracy of ciliary muscle measurements was improved when using reference points on the sclera to align the AS-OCT scan. The use of a ciliary muscle area metric demonstrated poor repeatability and reliability when compared to the traditional assessment of muscle morphology via thickness measurements. Physiological ageing in the crystalline lens occurs in line with ageing in other structures in the body. The methods for assessing accommodative function examined in previous chapters, were used to examine whether lifestyle factors which affect the rate of systemic ageing, such as smoking, also affect accommodative function. Although being a current smoker and having greater central adiposity was associated with a slower time for accommodative change, further research is required before these findings can be applied to the target population.

Os materiais restauradores estão evoluindo rapidamente e novas técnicas de inserção do compósito na cavidade restauradora estão sendo propostos. Dependendo da técnica, poderá ocorrer maior ou menor formação de bolhas na restauração final. A incorporação de bolhas entre as camadas do material restaurador pode gerar uma maior degradação da restauração em virtude da menor obtenção de propriedades físico-mecânicas do material. Assim, a necessidade de estudos sobre a prevalência de bolhas em restaurações confeccionadas com diferentes técnicas de inserção se faz necessária para a melhor compreensão do uso e do manuseio dos materiais. O objetivo desse trabalho foi analisar a ocorrência de bolhas e o volume de espaços presentes no interior de restaurações com resina composta, inserida na cavidade dental através das técnicas restauradoras: incremental e bulk fill. Quarenta e oito dentes molares humanos (n=24, duas restaurações por dente) foram selecionados e, nestes, foram confeccionados dois preparos por dente, um em cada região proximal, com profundidade de 4mm, largura de 4mm e distância axio-proximal de 2mm. Posteriormente, foram restaurados de acordo com os grupos: FiltekTM One Bulk Fill Restorative (FOB; 3M Oral Care); FiltekTM Z350 XT (FXT; 3M Oral care); FiltekTM Bulk Fill Flowable Restorative (FBF+FXT; 3M Oral care) e FiltekTM Z350 XT Flow (FF+FXT; 3M Oral care) . As resinas fluidas foram cobertas com a resina FiltekTM Z350 XT (3M Oral Care). Após 24 horas, os dentes restaurados foram submetidos à ciclagem térmica (5.000 ciclos) e posteriormente foi realizada a Tomografia de Coerência Ótica (OCT). Através da análise das imagens obtidas pelo OCT foram medidos os valores de quantidade de bolhas e porcentagem de espaços presentes nas restaurações. Os dados da presença de bolhas foram analisados estatisticamente com o teste Qui-Quadrado, os dados de número de bolhas e porcentagem de espaços obtidos foram analisados com o teste de Kruskall Wallis e a comparação entre os grupos foi feita pelo método de Dunn , com nível de significância de 5%. FF+FXT, apresentou bolhas em todas as restaurações e foi significativamente maior quando comparado a FXT (p=0,015). FF+FXT apresentou quantidade significativamente maior de bolhas (p<0,05) quando comparada com os outros três grupos. FBF+FXT apresentou a maior porcentagem de porosidade, devido ao maior tamanho de bolhas, porém esta porcentagem foi significantemente maior apenas quando comparada com FXT (p<0,05). Todos os grupos apresentaram bolhas. As técnicas restauradoras que apresentaram o pior desempenho, considerando o número de bolhas e a porcentagem de porosidade, foram aquelas realizadas com resina composta fluída. Não houve diferença estatisticamente significante quanto ao número de bolhas e à porcentagem de espaços entre as restaurações confeccionadas somente com resinas de alta viscosidade para as diferentes técnicas utilizadas neste estudo. / Dental restorative materials are quickly evolving, and new techniques are being proposed to change the way of filling dental cavities. Depending on the technique, a different number of voids could be generated inside the restauration. The appearance of these voids between layers of resin composite can significate a greater degradation of the material determined by low mechanical and physical properties. Therefore, to investigate voids prevalence at different restorative techniques is needed, in order to get a better understanding of the resin composites and their best handling. The objective of this project was to analyze the voids frequency inside and between the layers of the resin composite, filling class II cavities using incremental technique and bulk fill technique. Forty eight human teeth (n=24, two restorations per tooth) were selected and two cavities per tooth were made, one per each proximal area, 4mm of depth, 4mm height and 2mm of axio-proximal distance. After, they were divided in four groups and restored using FiltekTM One Bulk Fill Restorative (FOB; 3M Oral Care); FiltekTM Z350 XT (FXT; 3M Oral care); FiltekTM Bulk Fill Flowable Restorative (FBF+FXT; 3M Oral care) e FiltekTM Z350 XT Flow (FF+F; 3M Oral care), handled according to manufacturer instructions. Flowable resin composite was covered with FiltekTM Z350 (3M Oral Care). 24 hours later, thermocycling was conducted (5,000 cycles) and later Optical Coherence Tomography was performed. By analyzing the OCT images, number of voids and percentage of void volume were calculated. Presence of voids were analyzed by Chi-squared test, number of voids and percentage of void volume were analyzed by Kruskall Wallis test, and comparisons were performed by Dunn Method, at significance level of 5%.. FF+FXT had voids in all the restorations of the group, and it was significantly greater when compared with FXT (p=0.015). FF+FXT had statistically significant more number of voids (p<0.05) when compared with the others 3 groups. FBF+FXT had the highest percentage of voids volume, because the size of its voids, but this percentage was significantly different only when compared with FXT (p<0,05). All groups had voids. Restorative techniques that presented worst performance, considering number of voids and percentage of voids volume, were the ones made with flowable resin composite. Non statistical differences referred to a number of voids, neither percentage of voids volume among restorations made using only high viscosity resin.

Nous présentons d'abord un système de tomographie optique fonctionnant en lumière blanche, avec un interféromètre de Linnik. La résolution tomographique obtenue est de l'ordre de 1,2 m dans l'air. Les capacités de l'instrument sont illustrées par des images tomographiques d'intérêt biomédical. D'autre part, nous présentons un polarimètre de Mueller à cristaux liquides nématiques optimisé pour la propagation des erreurs de mesures brutes aux images finales. Les mesures sont rapides (de l'ordre de la seconde) et précises (erreurs de l'ordre de 1%). Les images polarimétriques de coupes histologiques montrent l'intérêt de ce dispositif pour l'étude microscopique d'échantillons contenant des macromolécules fibreuses (collagène). Enfin, des images en degré de polarisation (DOP) de cols de l'utérus humains ex vivo viennent confirmer les possibilités de l'imagerie polarimétrique pour la détection de dysplasies (DOP plus élevé que dans les zones saines).

Une peinture est un matériau complexe composé de plusieurs couches picturales. Ce travail de recherche poursuit un double but : comprendre et modéliser l'aspect visuel d'un tel milieu stratifié et développer des méthodes non destructives permettant d'identifier les différents constituants présents dans une œuvre d'art. L'équation de transfert radiatif, résolue par la méthode de la fonction auxiliaire, permet de modéliser l'aspect visuel des couches picturales stratifiées. Cette modélisation est validée par comparaison avec des spectres expérimentaux de réflexion diffuse. Expérimentalement, la reconnaissance des pigments et des colorants à partir d'un appareil déjà opérationnel au laboratoire a été étendue à celle des constituants d'un mélange de pigments. De plus, la tomographie optique cohérente (OCT), développée au cours de cette thèse, permet d'imager les pigments et d'obtenir une information spectrale permettant d'envisager une identification non destructive des composants de couches picturales stratifiées.

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La capacité de la tomographie par cohérence optique (OCT) à délivrer des images tomographiques de tissus biologiques in vivo, de manière non invasive et en temps réel, a suscité un intérêt croissant pour de nombreuses applications biomédicales, principalement en ophtalmologie pour l'imagerie de la rétine et du segment antérieur de l'œil. Toutefois, pour l'imagerie à haute résolution de tissus biologiques fortement diffusants, comme la sclérotique et la cornée œdémateuse, la technique nécessitait des améliorations technologiques. Dans cette thèse, un système d'OCT " Fourier-domain " (FD-OCT) à très haute résolution spatiale (< 4 µm), à la longueur d'onde de 1,3 µm, a été développé dans la Laboratoire Charles Fabry - Institute d'Optique Graduate School. Avec ce système original, nous avons réussi, pour la première fois, à visualiser correctement le canal de Schlemm de l'œil humain qui se trouve à une profondeur d'environ 0,8 mm dans le limbe de la cornée, milieu fortement diffusant. L'imagerie du canal de Schlemm est capitale afin d'envisager la chirurgie par laser du glaucome, qui consiste à inciser cette partie de l'œil afin d'améliorer l'écoulement de l'humeur aqueuse. Par ailleurs, en collaboration avec le Laboratoire d'Optique Appliquée de l'ENSTA ParisTech, nous avons démontré la possibilité de contrôler en temps réel par OCT des découpes par laser femtoseconde pratiquées dans la cornée humaine in vitro. Ces travaux ont montré que l'opération du Glaucome par laser femtoseconde, contrôlée par OCT, devrait être possible.