The main aim of this thesis is to evaluate the effect of meridional blur, using refractive induced astigmatism, on visual performance at far and close distances. Visual performance was evaluated using letter discrimination tasks at distance and near (visual acuity, VA) and a reading task at near on subjects with pharmacologically blocked (young) or absent accommodation (presbyopic and pseudophakic). The effect of astigmatism was tested using positive cylindrical lenses oriented at 180 and 90 degrees, these simulating with- (WTR) and against-the-rule (ATR) astigmatism. Other refractive status were also evaluated, namely, in-focus and spherical defocus. The visual performance data were correlated with biometric measurements (pupil size, anterior chamber depth (ACD), corneal and ocular aberrations, corneal multifocality, patient age, axial length). Further, the functionality of meridional blur was evaluated for alphabets in addition to the standard Roman alphabet using a VA task. The results confirm that myopic astigmatism contributes to a better visual performance at closer distances, with ATR astigmatism providing higher performance for reading tasks compared to other forms of astigmatism. Anatomical factors such as pupil size, corneal multifocality and ACD were significantly correlated visual performance, while other ocular characteristics were not. Ray tracing modelling using wavefront data was a moderate predictor of VA and reading acuity. The results of the effect of meridional blur orientation on alphabets other than the Roman alphabet, suggest that visual performance is dependent on the interaction between blur orientation and letter¿s spatial characteristics. In conclusion, pseudoaccommodation is a multifactorial phenomenon with pupil size being the major contributor for the improvement in visual performance. Against-the-rule shows advantages over WTR astigmatism, by providing higher reading performance, however extending the present and previous findings for clinical application will require further investigation on the effect of meridional blur in common and socio-culturally adapted tasks. / Bradford School of Optometry and Vision Sciences

Purpose: To determine whether symptoms of dizziness and fall rates change due to routine cataract surgery and to determine the influence of visual and refractive factors on these common problems in older adults. Methods: Self-reported dizziness and falls were determined in 287 subjects (mean age of 76.5±6.3 years, 55% females) before and after routine cataract surgery for the first (81, 28%), second (109, 38%) and both eyes (97, 34%). Six-month falls rates were determined using self-reported retrospective data. Dizziness was determined using the short-form of the Dizziness Handicap Inventory. Results: The number of patients with dizziness reduced significantly after cataract surgery (52% vs. 38%; χ2 = 19.14 , p<0.001), but the reduction in number of patients who fell in the 6-months post surgery was not significant (23% vs. 20%; χ2= 0.87, p=0.35). Multivariate logistic regression analyses found significant links between post-operative falls and change in spectacle type (increased risk if switched into multifocal spectacles). Post-operative dizziness was associated with changes in best eye visual acuity and changes in oblique astigmatic correction. Conclusions: Dizziness is significantly reduced by cataract surgery and this is linked with improvements in best eye visual acuity, although changes in oblique astigmatic correction increased dizziness. The lack of improvement in falls rate may be associated with switching into multifocal spectacle wear after surgery. / The Dunhill Medical Trust

Cryo-electron microscopy (cryo-EM) has been established as the leading imaging technique for structural studies from small proteins to whole cells at a molecular level. The great advances in cryo-EM have led to the ability to provide unique insights into a wide variety of biological processes in a close to native, hydrated state at near-atomic resolutions. The developments of computational approaches have significantly contributed to the exciting achievements of cryo-EM. This dissertation emphasizes new approaches to address image processing problems in cryo-EM, including tilt series alignment evaluation, simultaneous determination of sample thickness, tilt, and electron mean free path based on Beer-Lambert law, Model-Based Iterative Reconstruction (MBIR) on tomographic data, minimization of objective lens astigmatism in instrument alignment and defocus and magnification dependent astigmatism of TEM images. The final goal of these methodological developments is to improve the 3D reconstruction of cryo-EM and visualize more detailed characterization.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-11-20T11:50:42Z No. of bitstreams: 2 Dissertação - Kariza Aiko Frantz - 2013.pdf: 1304781 bytes, checksum: 46fccae953bdf84df478afc21a321d58 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-11-20T14:18:24Z (GMT) No. of bitstreams: 2 Dissertação - Kariza Aiko Frantz - 2013.pdf: 1304781 bytes, checksum: 46fccae953bdf84df478afc21a321d58 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-20T14:18:24Z (GMT). No. of bitstreams: 2 Dissertação - Kariza Aiko Frantz - 2013.pdf: 1304781 bytes, checksum: 46fccae953bdf84df478afc21a321d58 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-09-24 / The purpose was to determine, using Orbscan examination, if dermatochalasis can lead to changes in corneal topography and to correlate any changes in corneal topography after blepharoplasty with the intensity of dermatochalasis. We analyzed 46 eyes from 23 patients without eyelid or corneal pathologies. We obtained measurements of the distance between the upper eyelid margin and upper eyelid crease (margin-crease distance) through digital images. Orbscan examinations were performed before and after upper blepharoplasty. The patients' age ranged from 41 to 64 years, with 01 (4.3%) male and 22 (96.7%) females. There was no statistically significant difference between the topographic parameters analyzed before and after upper blepharoplasty. Also there was no correlation between the margin-crease distance in millimeters and the difference of astigmatism after blepharoplasty. We conclude that dermatochalasis, in this study, did not lead to changes in corneal topography. The corneal astigmatism did not change significantly after upper blepharoplasty. / O objetivo do estudo foi determinar, por meio do exame de Orbscan, se a dermatocálase pode levar a alterações na topografia corneana e correlacionar as eventuais mudanças na topografia corneana, após a blefaroplastia, com a intensidade da dermatocálase. Foram analisados 46 olhos de 23 indivíduos sem doenças palpebrais ou corneanas. Foram obtidas medidas da distância entre a margem palpebral superior e o sulco palpebral superior através de imagens digitais. Exames de Orbscan foram realizados antes e 60 dias após a blefaroplastia superior. A faixa etária variou entre 41 e 64 anos, sendo 1 (4,3%) do sexo masculino e 22 (96,7%) do sexo feminino. Não houve diferença estatisticamente significativa entre os parâmetros topográficos analisados antes e após a blefaroplastia superior. Também não se observou correlação entre a distância margem-sulco em milímetros e a diferença de astigmatismo após a blefaroplastia. Concluiu-se que o exame de Orbscan não detectou alterações significativas na topografia corneana em olhos com dermatocálase após cirurgia de blefaroplastia superior. Este estudo evidenciou correlação fraca entre a intensidade da dermatocálase e as mudanças nos parâmetros avaliados pelo orbscan antes e após a blefaroplastia superior.

The aim of this master's thesis is to explore and study dynamic aberration correction options in electron-beam lithography systems. For the calculations, the thesis uses the optical column of the BS600 electron-beam writer. The thesis focuses on corrections of the third order field curvature, astigmatism, and distortion aberrations of the currently used magnetic deflection system and a newly designed electrostatic deflection system. The parameters of the two deflection and correction systems were compared.

In space exploration optical imaging is one of the key measurements conducted, with a vast majority of missions heavily relying on optical data acquisition to examine alien worlds. One such endeavor is ESA’s F-class mission Comet Interceptor, a multi-element spacecraft expected to be launched in 2028. It consists of a primary platform and two sub-spacecraft, one of which carrying the Optical Periscopic Imager for Comets (OPIC). An accurate prediction of the generated imagery is of undeniable importance as mission planning and instrument design strongly depend on the real-world output quality of the camera system. In the case of OPIC, the collected image data will be used to reconstruct three dimensional models of targeted celestial bodies. Furthermore, the sub-spacecraft faces a risk of high velocity dust impacts, leading to a limited number of data samples to be broadcasted back to the primary spacecraft before collision. Testing image prioritization algorithms and reconstruction methods prior to mission start requires accurate computer-generated images. Camera sensors and lens systems are subjected to various optical distortions and aberrations that degrade the final image. Popular render engines model those effects to a certain degree only and as a result produce content that is looking too perfect. While more sophisticated software products exist, they often come with compatibility limitations and other drawbacks. This report discusses the most important optical aberrations, as well as their relevance for optical instruments in space applications with a particular focus on the Comet Interceptor mission. The main part of this work is however the implementation of a dedicated software tool that simulates a variety of optical aberrations complementing the basic camera model of the Blender render engine. While its functionality is mostly demonstrated for OPIC, the software is designed with a broad range of usage scenarios in mind.

OBJETIVO: Avaliar comparativamente os resultados de duas técnicas de cirurgia refrativa de superfície com excimer laser, ceratectomia fotorrefrativa (PRK) e ceratectomia subepitelial borboleta assistida à laser (LASEKb). LOCAL: Hospital de Olhos Sadalla Amin Ghanem, Joinville, Santa Catarina, Brasil. MÉTODOS: Realizou-se um estudo prospectivo, randomizado e duplo-cego envolvendo 102 olhos de 51 pacientes. Cada paciente teve aleatoriamente um dos olhos operado com a técnica do PRK e o outro com LASEKb. Os pacientes foram acompanhados por 1 ano. RESULTADOS: Não houveram diferenças significativas entre os dois grupos na acuidade visual (AV) para longe, sem correção, (P = 0,5593). No 12o mês pós-operatório (PO), 98,04% dos olhos no grupo do PRK e 96,08% no grupo do LASEKb atingiram AV sem correção de 20/20. A previsibilidade, eficácia, segurança e estabilidade não apresentaram diferença estatisticamente significativa entre os grupos. O índice de segurança foi de 1 no PRK e 0,996 no LASEKb. Um olho do grupo do LASEKb perdeu uma linha de visão. A porcentagem de olhos que apresentou EE aos 12 meses na faixa de ±0,50 D foi de 94,1% no grupo do PRK e de 86,3% no grupo do LASEKb (P = 0,1883). Enquanto que na faixa de ±1,0 D foi de 100% no grupo do PRK e 98% no grupo do LASEKb (P = 0,3125). Não houve necessidade de reoperações. O tempo médio de cirurgia na técnica PRK foi de 304,86 + 58,77 segundos (aproximadamente 5 minutos) e na técnica LASEKb de 608,35 + 76,88 segundos (aproximadamente 10 minutos) (P < 0,001). O tempo médio de reepitelização no grupo do PRK foi de 4,35 ± 0,48 dias (variação, 4 a 5 dias) e no grupo do BLASEK foi de 4,75 ± 0,72 dias (variação, 4 a 6 dias) (P < 0,002). Os níveis de dor e o desconforto ocular PO não foram estatisticamente diferentes entre os grupos, entretanto houve uma tendência para menor dor no PRK (3,31 ± 4,09 vs 4,43 ± 4,27; P = 0,18). Houve uma redução estatisticamente significativa nos valores do teste de Schirmer em todas as avaliação PO, tanto no PRK (23,6 ± 8,1 vs 19,4 ± 10,1; P < 0,002) quanto no LASEKb (22,4 ± 8,7 vs 18,9 ± 9,7; P = 0,01), entretanto não houve diferença entre os grupos. A opacificação corneana (OC) PO foi pequena nos dois grupos. Somente no 1o mês foi observado diferença estatística entre os grupos, com maior intensidade da OC no grupo do LASEKb (0,18 ± 0,3881) quando comparado ao PRK (0,08 ± 0,2109) (P = 0,039936). A maior intensidade foi observada no 3o mês, com redução gradativa até o 12o mês. CONCLUSÃO: Dentro das condições deste estudo, conclui-se que o PRK e o LASEKb mostraram resultados semelhantes, exceto que o PRK apresentou menor tempo cirúrgico, reepitelização corneana mais rápida e menor OC no 30o PO. / PURPOSE: Comparatively evaluate the results of two techniques of surface excimer laser refractive surgery, photorefractive keratectomy (PRK) and butterfly laser-assisted subepithelial keratectomy (BLASEK). SETTING: Sadalla Amin Ghanem Eye Hospital, Joinville, Santa Catarina, Brazil. METHODS: This is a prospective, randomized and double-masked study including 102 eyes from 51 patients. Each patient was randomized to have one eye operated on with PRK and the other with BLASEK. Patients were followed for 1 year. RESULTS: There were no significant differences between the groups regarding uncorrected distant visual acuity (VA) (p= 0.5593). On the 12th post-operative (PO) month, 98.04% of the eyes in the PRK group and 96.08% in the BLASEK group reached uncorrected VA of 20/20. The predictability, efficacy, safety and stability did not present statically significant difference between groups. The safety index was of 1 for PRK and 0.996 for BLASEK. One eye of the BLASEK group lost one line on the 12th PO month. The percentage of the eyes that presented spherical equivalent at 12 months in the range of ±0.50 D was 94.1% in the PRK group and 86.3% in the BLASEK group (p = 0.1883). While in the range of ±1.0 D it was 100% in the PRK group and 98% in the BLASEK group (p = 0.3125). There were no retreatments. The mean surgical time was 304.86 + 58.77 seconds (approximately 5 minutes) in PRK and 608.35 + 76.88 seconds in BLASEK (approximately 10 minutes) (P < 0,001). The mean reepithelization time in the PRK group was 4.35 ± 0.48 days (range, 4 to 5 days), and in the BLASEK group was 4.75 ± 0.72 days (range, 4 to 6 days) (P < 0.002). Pain scores and ocular discomfort were not statistically different between groups, although there was a trend towards a lower pain level with PRK (3.31 ± 4.09 vs. 4.43 ± 4.27; P = 0.18). Schirmer test values were significantly reduced from preoperative levels through 12 months with both PRK (23.6 ± 8.1 vs. 19.4 ± 10.1; P < 0.002) and BLASEK (22.4 ± 8.7 vs. 18.9 ± 9.7; P = 0.01), however there was no difference between groups in any time point. Haze incidence was slight in both groups. Only in the 1st PO month statistical difference between the groups was observed, with higher intensity in the BLASEK group (0.18 ± 0.3881) when compared to the PRK (0.08 ± 0.2109) (p = 0.039936). The highest intensity was observed on the 3rd month, with gradual reduction until the 12th month. CONCLUSION: In the conditions of this study, it can be concluded that PRK and BLASEK showed similar results, except that PRK presented shorter surgical time, faster corneal reepithelization and less haze at 30th PO days.

OBJETIVO: Avaliar comparativamente os resultados de duas técnicas de cirurgia refrativa de superfície com excimer laser, ceratectomia fotorrefrativa (PRK) e ceratectomia subepitelial borboleta assistida à laser (LASEKb). LOCAL: Hospital de Olhos Sadalla Amin Ghanem, Joinville, Santa Catarina, Brasil. MÉTODOS: Realizou-se um estudo prospectivo, randomizado e duplo-cego envolvendo 102 olhos de 51 pacientes. Cada paciente teve aleatoriamente um dos olhos operado com a técnica do PRK e o outro com LASEKb. Os pacientes foram acompanhados por 1 ano. RESULTADOS: Não houveram diferenças significativas entre os dois grupos na acuidade visual (AV) para longe, sem correção, (P = 0,5593). No 12o mês pós-operatório (PO), 98,04% dos olhos no grupo do PRK e 96,08% no grupo do LASEKb atingiram AV sem correção de 20/20. A previsibilidade, eficácia, segurança e estabilidade não apresentaram diferença estatisticamente significativa entre os grupos. O índice de segurança foi de 1 no PRK e 0,996 no LASEKb. Um olho do grupo do LASEKb perdeu uma linha de visão. A porcentagem de olhos que apresentou EE aos 12 meses na faixa de ±0,50 D foi de 94,1% no grupo do PRK e de 86,3% no grupo do LASEKb (P = 0,1883). Enquanto que na faixa de ±1,0 D foi de 100% no grupo do PRK e 98% no grupo do LASEKb (P = 0,3125). Não houve necessidade de reoperações. O tempo médio de cirurgia na técnica PRK foi de 304,86 + 58,77 segundos (aproximadamente 5 minutos) e na técnica LASEKb de 608,35 + 76,88 segundos (aproximadamente 10 minutos) (P < 0,001). O tempo médio de reepitelização no grupo do PRK foi de 4,35 ± 0,48 dias (variação, 4 a 5 dias) e no grupo do BLASEK foi de 4,75 ± 0,72 dias (variação, 4 a 6 dias) (P < 0,002). Os níveis de dor e o desconforto ocular PO não foram estatisticamente diferentes entre os grupos, entretanto houve uma tendência para menor dor no PRK (3,31 ± 4,09 vs 4,43 ± 4,27; P = 0,18). Houve uma redução estatisticamente significativa nos valores do teste de Schirmer em todas as avaliação PO, tanto no PRK (23,6 ± 8,1 vs 19,4 ± 10,1; P < 0,002) quanto no LASEKb (22,4 ± 8,7 vs 18,9 ± 9,7; P = 0,01), entretanto não houve diferença entre os grupos. A opacificação corneana (OC) PO foi pequena nos dois grupos. Somente no 1o mês foi observado diferença estatística entre os grupos, com maior intensidade da OC no grupo do LASEKb (0,18 ± 0,3881) quando comparado ao PRK (0,08 ± 0,2109) (P = 0,039936). A maior intensidade foi observada no 3o mês, com redução gradativa até o 12o mês. CONCLUSÃO: Dentro das condições deste estudo, conclui-se que o PRK e o LASEKb mostraram resultados semelhantes, exceto que o PRK apresentou menor tempo cirúrgico, reepitelização corneana mais rápida e menor OC no 30o PO. / PURPOSE: Comparatively evaluate the results of two techniques of surface excimer laser refractive surgery, photorefractive keratectomy (PRK) and butterfly laser-assisted subepithelial keratectomy (BLASEK). SETTING: Sadalla Amin Ghanem Eye Hospital, Joinville, Santa Catarina, Brazil. METHODS: This is a prospective, randomized and double-masked study including 102 eyes from 51 patients. Each patient was randomized to have one eye operated on with PRK and the other with BLASEK. Patients were followed for 1 year. RESULTS: There were no significant differences between the groups regarding uncorrected distant visual acuity (VA) (p= 0.5593). On the 12th post-operative (PO) month, 98.04% of the eyes in the PRK group and 96.08% in the BLASEK group reached uncorrected VA of 20/20. The predictability, efficacy, safety and stability did not present statically significant difference between groups. The safety index was of 1 for PRK and 0.996 for BLASEK. One eye of the BLASEK group lost one line on the 12th PO month. The percentage of the eyes that presented spherical equivalent at 12 months in the range of ±0.50 D was 94.1% in the PRK group and 86.3% in the BLASEK group (p = 0.1883). While in the range of ±1.0 D it was 100% in the PRK group and 98% in the BLASEK group (p = 0.3125). There were no retreatments. The mean surgical time was 304.86 + 58.77 seconds (approximately 5 minutes) in PRK and 608.35 + 76.88 seconds in BLASEK (approximately 10 minutes) (P < 0,001). The mean reepithelization time in the PRK group was 4.35 ± 0.48 days (range, 4 to 5 days), and in the BLASEK group was 4.75 ± 0.72 days (range, 4 to 6 days) (P < 0.002). Pain scores and ocular discomfort were not statistically different between groups, although there was a trend towards a lower pain level with PRK (3.31 ± 4.09 vs. 4.43 ± 4.27; P = 0.18). Schirmer test values were significantly reduced from preoperative levels through 12 months with both PRK (23.6 ± 8.1 vs. 19.4 ± 10.1; P < 0.002) and BLASEK (22.4 ± 8.7 vs. 18.9 ± 9.7; P = 0.01), however there was no difference between groups in any time point. Haze incidence was slight in both groups. Only in the 1st PO month statistical difference between the groups was observed, with higher intensity in the BLASEK group (0.18 ± 0.3881) when compared to the PRK (0.08 ± 0.2109) (p = 0.039936). The highest intensity was observed on the 3rd month, with gradual reduction until the 12th month. CONCLUSION: In the conditions of this study, it can be concluded that PRK and BLASEK showed similar results, except that PRK presented shorter surgical time, faster corneal reepithelization and less haze at 30th PO days.

MPH / Department of Public Health / See the attached abstract below

This thesis describes the physical nature of corrections of an electron microscope and mathematical methods of image processing required for their complete automation. The corrections include different types of focusing, astigmatism correction, electron beam centring, and image stabilisation. The mathematical methods described in this thesis include various methods of measuring focus and astigmatism, with and without using the Fourier transform, edge detection, histogram operations, and image registration, i.e. detection of spatial transformations in images. This thesis includes detailed descriptions of the mathematical methods, their evaluation using an “offline” application, descriptions of the algorithms of their implementation into an actual electron microscope and results of their testing on the actual electron microscope, in the form of a video footage grabbed from its control computer’s screen.