BACKGROUND: Intraocular scatter is an important factor when considering the performance of the human eye as it can negatively affect visual performances (e.g. glare). However, and in contrast to other optical factors that also affect vision such as high order aberrations, there is currently no efficient method to measure accurately and objectively the amount and the angular distribution of forward light scatter in the eye. Various methods and instruments exist to assess forward light scatter (FLS) but the relation between these methods has rarely been quantified. In addition, FLS measurements obtained with existing instruments cannot be related to any physiological factors due to the absence of a valid model. PURPOSE: To investigate the relations between some of the main methods to measure forward light scatter, and to develop an experimental set -up for the objective measurement of forward light scatter that could be ideally related to physiological parameters. METHODS: After a short review of intraocular light scatter, the three main methods used to assess forward light scattering are compared. In this sense, the C-quant (CQ) straylight meter is compared to the van den Berg (VDB) straylight meter and the Hartmann-Shack spot pattern analysis obtained from the Hartmann-Shack aberrometer. The potential of the new Oculus Pentacam functionalities for providing information on backward light scatter (BLS) are also investigated. Finally, an innovative prototype for objective assessment of intraocular light scattering together with a scatter model of the eye is presented. RESULTS and DISCUSSION: Although no significant relationship was found between the different instruments considered (VDB straylight meter, CQ, Pentacam), our results allowed us to clarify some possible confusion introduced by previously published results and to illustrate the fact that existing commercial instruments such as aberrometers and the Pentacam cannot be used to measure FLS without at least some major modifications (hardware or software). Preliminary results with the prototype built in this study suggest that it could be used for the objective measurement of intraocular light scatter. Relating this measurement to physiological parameters stays however elusive, a fact that widens the future scope of this research.

PURPOSE. To evaluate light scatter and stray light in intraocular lenses (IOLs) explanted because of postoperative opacification (13 calcified hydrophilic acrylic, 1 calcified silicone, and 4 polymethylmethacrylate [PMMA] lenses with snowflake degeneration), as well as effect of opacification on other optical quality/performance indicators, in comparison with controls. METHODS. The Complete Angle Scatter Instrument (CASI) scatterometer was used to measure the forward light scattering (FLS) of the IOLs, and the stray light values at various angles were calculated from the measured FLS. Modulation transfer function (MTF) was obtained with an optical bench, and a Badal optometer was used to obtain letter chart images through the lenses. Back light scatter and light transmittance were also measured. RESULTS. Average stray light values (Log (s)) at a scattered angle of 100 were 1.79 +/- 0.37 for hydrophilic acrylic IOLs (controls 0.36 +/- 0.05), 1.53 for the silicone lens (control 0.41), and 1.62 +/- 0.46 for PMMA IOLs (control 0.25). Stray light was significantly higher for explanted opacified lenses (N = 18) in comparison with controls (N = 7; two-tail P < 0.001 at 100). Modulation transfer function and Badal image contrast were drastically reduced in lenses with calcification and snowflake degeneration. CONCLUSIONS. Different studies described the impact of stray light in human vision, with serious hindrance above 1.47 Log (s). Lenses explanted from patients because of clinically significant opacification are associated with a considerable increase in light scatter and stray light, as well as with a decline of other optical quality/performance indicators.

Avaliar a dispersão de luz intraocular em participantes com olhos saudáveis, moradores da Grande São Paulo e de San Miguel de Tucuman, Argentina, e pacientes que realizariam cirurgia refrativa (LASIK), utilizando o metodo psicofísico da Comparacão da Compensação presente no aparelho C-Quant (Oculus Optikgerate, Alemanha). Método: Foi utilizado o aparelho C-Quant, desenvolvido por Franssen, Coppens e van den Berg. (IOVS, 47:768,2006), disponivel comercialmente, para avaliar de maneira objetiva a dispersão de luz intraocular atraves de metodo psicofisico. Foram testados 261 voluntarios, de ambos os sexos, com idades variando entre 10 e 78 anos, divididos em tres grupos experimentais: grupo 1: n= 209, idade: 33,74 } 15,87 anos, moradores da Grande Sao Paulo; grupo 2: n=29, idade: 39,72}13,28 anos, moradores de San Miguel de Tucuman, Argentina; grupo 3: n=23, idade: 30,52}4,94 anos, moradores da Grande Sao Paulo e pacientes de cirurgia refrativa (LASIK). Cada voluntario realizou 6 testes, 3 em cada olho (olhos alternados), e os valores obtidos do parametro de dispersao foram comparados entre si e com as normas do equipamento. Os voluntarios do grupo 3 realizaram tres sessoes de testagem, antes da cirurgia, apos 60 dias da cirurgia e apos 120 dias da cirurgia. Resultados: Observou-se que, apesar da variacao entre respostas do mesmo participante e de diferentes participantes da mesma idade, nao houve significancia estatistica (ANOVA medidas pareadas, grupo 1: t=1,501, Wilcoxon, grupo 2: Z=-2,422, p-level 0,015) entre os dados, e em todos os grupos experimentais houve alta correlacao (grupo 1: Pearson: R=0,7101, grupo 2: Spearman = 0,942, grupo 3: Spearman = 0,958) entre olho direito e esquerdo. Comparando-se com as normas do aparelho atualizadas, nao foi encontrada diferenca estatistica para os tres grupos experimentais. No grupo 3, os resultados de dispersao pre-operatorio foram ligeiramente maiores que os obtidos com 60 e 120 dias de pos-operatorio, porem nao houve diferenca estatistica entre tais dados. Discussão: Os valores de dispersao de luz intraocular foram compativeis com as normas atualizadas do aparelho, o que se deve, principalmente, a grande variacao dos dados coletados, levando a um desvio padrao grande, que impossibilita qualquer diferenca estatistica. Observamos que entre os mais jovens (entre 10 e 20 anos), tais variacoes de valores de dispersao tambem ocorrem, levantando duvidas sobre a constancia da dispersao de luz nessa faixa etaria, fato predito na literatura. Observamos tambem uma diminuicao nos valores de dispersao no pos-operatorio a niveis normais, indicando recuperacao dos meios opticos apos a cirurgia. Nao foram observadas diferencas significativas entre a populacao brasileira e a argentina, nem entre participantes de olhos de cores diferentes, o que vai contra a literatura, que prediz valores maiores de dispersao para olhos claros / Purpose: Evaluate retinal straylight in healthy eyes of people living in Sao Paulo and San Miguel de Tucuman, Argentina, and in patients of refractive surgery (LASIK), using the psychophysical method Compensation Comparison as presented in the Oculus C-Quant (Oculus Optikgerate, Germany). Methods: Oculus C-Quant was used to access the retinal straylight, as developed by Franssen, Coppens and van den Berg (IOVS, 47:768,2006), using a psychophysical method to quantify retinal straylight. For this study 261 subjects were tested, both sexes, ages between 10 and 78 years old, arranged in three experimental groups: group 1, n=209, age: 33,74 } 15,87 years, all living in Sao Paulo; group 2: n=29, age: 39,72}13,28 years, living in San Miguel de Tucuman, Argentina; group 3: n=23, age: 30,52}4,94 years, living in Sao Paulo and all refractive surgery (LASIK) patients. Each subject performed the test 6 times, 3 times each eye (alternating eyes), and the straylight values were compared between measures on the same subject and with the updated standard norms of the C-Quant. Group 3 subjects were tested three times, one previously the refractive surgery, one 60 days after surgery and the last one 120 days after surgery. Results: As a result, there were no statistic differences between measures on the same subject and when comparing different subjects same age (Paired Measures ANOVA, group 1, t=1,501, Wilcoxon, group 2: Z=-2,422, p-level 0,015), and there were high correlation between right and left eyes for all three groups (group 1: Pearson: R=0,7101, group 2: Spearman = 0,942, group 3: Spearman = 0,958). The standard norms of the C-Quant were also compared with the straylight values for the subjects in all three groups, and also there was no statistical significance between them. At group 3, the pre-op results were slightly higher than the post-op (both 60 and 120 days), but no statistical difference was found. Discussion: The straylight values obtained were similar to those on the updated standard norms of the test, due mainly to data scatter and therefore high standard deviation values. Among the younger subjects (ages between 10 and 20 years) the straylight values also vary and didnt remain constant as predicted by literature. At group 3, straylight values on postop (60 and 120 days) were similar those from updated norms, indicating a recovery of the eye media after surgery. No statistical differences were found between Brazilian and Argentinean subjects, neither between dark and light eyes subjects, although the literature predicts higher straylight values for light eyes

Avaliar a dispersão de luz intraocular em participantes com olhos saudáveis, moradores da Grande São Paulo e de San Miguel de Tucuman, Argentina, e pacientes que realizariam cirurgia refrativa (LASIK), utilizando o metodo psicofísico da Comparacão da Compensação presente no aparelho C-Quant (Oculus Optikgerate, Alemanha). Método: Foi utilizado o aparelho C-Quant, desenvolvido por Franssen, Coppens e van den Berg. (IOVS, 47:768,2006), disponivel comercialmente, para avaliar de maneira objetiva a dispersão de luz intraocular atraves de metodo psicofisico. Foram testados 261 voluntarios, de ambos os sexos, com idades variando entre 10 e 78 anos, divididos em tres grupos experimentais: grupo 1: n= 209, idade: 33,74 } 15,87 anos, moradores da Grande Sao Paulo; grupo 2: n=29, idade: 39,72}13,28 anos, moradores de San Miguel de Tucuman, Argentina; grupo 3: n=23, idade: 30,52}4,94 anos, moradores da Grande Sao Paulo e pacientes de cirurgia refrativa (LASIK). Cada voluntario realizou 6 testes, 3 em cada olho (olhos alternados), e os valores obtidos do parametro de dispersao foram comparados entre si e com as normas do equipamento. Os voluntarios do grupo 3 realizaram tres sessoes de testagem, antes da cirurgia, apos 60 dias da cirurgia e apos 120 dias da cirurgia. Resultados: Observou-se que, apesar da variacao entre respostas do mesmo participante e de diferentes participantes da mesma idade, nao houve significancia estatistica (ANOVA medidas pareadas, grupo 1: t=1,501, Wilcoxon, grupo 2: Z=-2,422, p-level 0,015) entre os dados, e em todos os grupos experimentais houve alta correlacao (grupo 1: Pearson: R=0,7101, grupo 2: Spearman = 0,942, grupo 3: Spearman = 0,958) entre olho direito e esquerdo. Comparando-se com as normas do aparelho atualizadas, nao foi encontrada diferenca estatistica para os tres grupos experimentais. No grupo 3, os resultados de dispersao pre-operatorio foram ligeiramente maiores que os obtidos com 60 e 120 dias de pos-operatorio, porem nao houve diferenca estatistica entre tais dados. Discussão: Os valores de dispersao de luz intraocular foram compativeis com as normas atualizadas do aparelho, o que se deve, principalmente, a grande variacao dos dados coletados, levando a um desvio padrao grande, que impossibilita qualquer diferenca estatistica. Observamos que entre os mais jovens (entre 10 e 20 anos), tais variacoes de valores de dispersao tambem ocorrem, levantando duvidas sobre a constancia da dispersao de luz nessa faixa etaria, fato predito na literatura. Observamos tambem uma diminuicao nos valores de dispersao no pos-operatorio a niveis normais, indicando recuperacao dos meios opticos apos a cirurgia. Nao foram observadas diferencas significativas entre a populacao brasileira e a argentina, nem entre participantes de olhos de cores diferentes, o que vai contra a literatura, que prediz valores maiores de dispersao para olhos claros / Purpose: Evaluate retinal straylight in healthy eyes of people living in Sao Paulo and San Miguel de Tucuman, Argentina, and in patients of refractive surgery (LASIK), using the psychophysical method Compensation Comparison as presented in the Oculus C-Quant (Oculus Optikgerate, Germany). Methods: Oculus C-Quant was used to access the retinal straylight, as developed by Franssen, Coppens and van den Berg (IOVS, 47:768,2006), using a psychophysical method to quantify retinal straylight. For this study 261 subjects were tested, both sexes, ages between 10 and 78 years old, arranged in three experimental groups: group 1, n=209, age: 33,74 } 15,87 years, all living in Sao Paulo; group 2: n=29, age: 39,72}13,28 years, living in San Miguel de Tucuman, Argentina; group 3: n=23, age: 30,52}4,94 years, living in Sao Paulo and all refractive surgery (LASIK) patients. Each subject performed the test 6 times, 3 times each eye (alternating eyes), and the straylight values were compared between measures on the same subject and with the updated standard norms of the C-Quant. Group 3 subjects were tested three times, one previously the refractive surgery, one 60 days after surgery and the last one 120 days after surgery. Results: As a result, there were no statistic differences between measures on the same subject and when comparing different subjects same age (Paired Measures ANOVA, group 1, t=1,501, Wilcoxon, group 2: Z=-2,422, p-level 0,015), and there were high correlation between right and left eyes for all three groups (group 1: Pearson: R=0,7101, group 2: Spearman = 0,942, group 3: Spearman = 0,958). The standard norms of the C-Quant were also compared with the straylight values for the subjects in all three groups, and also there was no statistical significance between them. At group 3, the pre-op results were slightly higher than the post-op (both 60 and 120 days), but no statistical difference was found. Discussion: The straylight values obtained were similar to those on the updated standard norms of the test, due mainly to data scatter and therefore high standard deviation values. Among the younger subjects (ages between 10 and 20 years) the straylight values also vary and didnt remain constant as predicted by literature. At group 3, straylight values on postop (60 and 120 days) were similar those from updated norms, indicating a recovery of the eye media after surgery. No statistical differences were found between Brazilian and Argentinean subjects, neither between dark and light eyes subjects, although the literature predicts higher straylight values for light eyes

La mission BepiColombo est une des pierres angulaires du programme scientifique de l'ESA. Elle permettra l'étude de la planète Mercure grâce à deux sondes mises en orbite autour de la planète. Une des deux sondes, Mercury Planetary Orbiter (MPO) développée par l'ESA, sera dédiée à l'étude de la surface et de l'intérieur de la planète. La mission est prévue pour un lancement en 2016 et une arrivée sur Mercure en janvier 2024. L’IAS est responsable de l’étalonnage de l'ensemble d'imageurs SIMBIO-SYS (Spectrometer and Imagers for MPO BepiColombo-Integrated Observatory SYStem) composé d’une caméra haute résolution (HRIC), d’une caméra stéréoscopique (STC) et d’un imageur hyperspectral visible et proche-infrarouge (VIHI). Ces instruments devraient profondément modifier nos connaissances de la composition et de la géomorphologie de la surface de Mercure. Ma thèse a consisté à participer à la définition et à la mise en place des caractéristiques et des fonctionnalités du dispositif expérimental d'étalonnage qui se compose principalement d’une cuve à vide contenant les instruments, d’un banc optique rassemblant les sources d'étalonnage et les éléments optiques qui reconstituent les conditions d'observation de Mercure, des interfaces mécaniques permettant le positionnement de l'expérience à l'intérieur de la cuve, des interfaces thermiques visant à explorer les températures de fonctionnement des différentes parties des expériences, des interfaces informatiques assurant la communication avec l'expérience et le pilotage du dispositif d'étalonnage en fonction des tests à réaliser. J’ai modélisés et validé expérimentalement certaines performances du dispositif. Enfin, j’ai défini en étroite collaboration avec les équipes italiennes co-responsables des trois instruments les différentes séquences d’étalonnage qui seront utilisées lors de l’étalonnage. / BepiColombo is one of the cornerstones of the scientific program of ESA. It will study the planet Mercury with two spacecrafts in orbit around the planet. One of the two spacecrafts, the Mercury Planetary Orbiter (MPO), will be dedicated to the study of the surface and interior of the planet. The mission is scheduled for launch in 2016 and arrival at Mercury in January 2024. IAS is responsible for the calibration of the imaging system SIMBIO-SYS (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory-SYStem) which consists of a high-resolution camera (HRIC), a stereoscopic camera (STC) and a visible and near-infrared hyperspectral imager (VIHI). These instruments should deeply change our understanding of the composition and geomorphology of Mercury surface. My research subject allowed me to participate in all the activities concerning the definition, implementation and validation of the calibration facilities at the IAS. These facilities are divided into different sub-systems: a thermal vacuum chamber containing the instrument during all the calibration campaign that shall simulate the environmental conditions (temperature and pressure), an optical bench with optical components and radiometrically calibrated sources reproducing the observational conditions as it will be seen by the instrument once placed in Mercury’s orbit, mechanical interfaces allowing the positioning and guidance of the instrument when placed inside the vacuum chamber with the required precision and accuracy, thermal interfaces facilitating the thermal excursion of the detectors, software interfaces so as to automatize and control the entire system. I developed a radiometric model of the calibration system and instrument to refine the calibration sources. In parallel, I performed several measurements of some subsystems so as to validate the optical assembly and to improve its control. Finally as a result of a close collaboration with the three Italian scientific teams of the instrument, I elaborate the fully package of the calibration sequences and the detailed instrument configuration that will be used during the calibration campaign.