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778 results on '"Manns, Fabrice"'

101. In-vivo, real-time cross-sectional images of retina using a GPU enhanced master slave optical coherence tomography system

Author

Manns, Fabrice, Söderberg, Per G., Ho, Arthur, Bradu, Adrian, Kapinchev, Konstantin, Barnes, Frederick, Podoleanu, Adrian, Manns, Fabrice, Söderberg, Per G., Ho, Arthur, Bradu, Adrian, Kapinchev, Konstantin, Barnes, Frederick, and Podoleanu, Adrian

Abstract

In our previous reports we demonstrated a novel Fourier domain optical coherence tomography method, Master Slave optical coherence tomography (MS-OCT), that does not require resampling of data and can deliver en-face images from several depths simultaneously. While ideally suited for delivering information from a selected depth, the MS-OCT has been so far inferior to the conventional FFT based OCT in terms of time of producing cross section images. Here, we demonstrate that by taking advantage of the parallel processing capabilities offered by the MS-OCT method, cross-sectional OCT images of the human retina can be produced in real-time by assembling several T-scans from different depths. We analyze the conditions that ensure a real-time B-scan imaging operation, and demonstrate in-vivo real-time images from human fovea and the optic nerve, of comparable resolution and sensitivity to those produced using the traditional Fourier domain based method.

Published
2016

104. Quantification of the ciliary muscle and crystalline lens interaction during accommodation with synchronous OCT imaging

Author

Ruggeri, Marco, primary, de Freitas, Carolina, additional, Williams, Siobhan, additional, Hernandez, Victor M., additional, Cabot, Florence, additional, Yesilirmak, Nilufer, additional, Alawa, Karam, additional, Chang, Yu-Cherng, additional, Yoo, Sonia H., additional, Gregori, Giovanni, additional, Parel, Jean-Marie, additional, and Manns, Fabrice, additional

Published
2016
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107. Crystalline lens gradient refractive index and posterior surface shape from multiple orientations OCT imaging: towards a reconstruction in vivo?

Author

Alberto de Castro Arribas, Birkenfeld, Judith, Maceo, Bianca Maria, Ruggeri, Marco, Arrieta, Esdras A., Parel, Jean-Marie A., Manns, Fabrice, and Marcos, Susana

Subjects
sense organs, eye diseases
Abstract

Orlando, United States, 4–8 May 2014, The gradient index (GRIN) plays a key role in the crystalline lens optical properties, yet most current estimations are in vitro. We provide computational and experimental evidence to extend a method previously applied in vitro and reconstruct both the GRIN and posterior lens surface using optical coherence tomography (OCT) images obtained from multiple projections.

Published
2014

127. Distortion Correction of OCT Images of the Crystalline Lens: GRIN Approach

Author

Siedlecki, Damian, de Castro, Alberto, Gambra, Enrique, Ortiz, Sergio, Borja, David, Uhlhorn, Stephen, Manns, Fabrice, Marcos, Susana, and Parel, Jean-Marie

Subjects
Adult, Male, Adolescent, Accommodation, Ocular, Reproducibility of Results, Middle Aged, Refraction, Ocular, Article, Young Adult, Imaging, Three-Dimensional, Lens, Crystalline, Cadaver, Humans, Female, Child, Algorithms, Tomography, Optical Coherence, Aged
Abstract

To propose a method to correct optical coherence tomography (OCT) images of posterior surface of the crystalline lens incorporating its gradient index (GRIN) distribution and explore its possibilities for posterior surface shape reconstruction in comparison to existing methods of correction.Two-dimensional images of nine human lenses were obtained with a time-domain OCT system. The shape of the posterior lens surface was corrected using the proposed iterative correction method. The parameters defining the GRIN distribution used for the correction were taken from a previous publication. The results of correction were evaluated relative to the nominal surface shape (accessible in vitro) and compared with the performance of two other existing methods (simple division, refraction correction: assuming a homogeneous index). Comparisons were made in terms of posterior surface radius, conic constant, root mean square, peak to valley, and lens thickness shifts from the nominal data.Differences in the retrieved radius and conic constant were not statistically significant across methods. However, GRIN distortion correction with optimal shape GRIN parameters provided more accurate estimates of the posterior lens surface in terms of root mean square and peak values, with errors6 and 13 μm, respectively, on average. Thickness was also more accurately estimated with the new method, with a mean discrepancy of 8 μm.The posterior surface of the crystalline lens and lens thickness can be accurately reconstructed from OCT images, with the accuracy improving with an accurate model of the GRIN distribution. The algorithm can be used to improve quantitative knowledge of the crystalline lens from OCT imaging in vivo. Although the improvements over other methods are modest in two dimension, it is expected that three-dimensional imaging will fully exploit the potential of the technique. The method will also benefit from increasing experimental data of GRIN distribution in the lens of larger populations.

Published
2012

128. Changes in monkey crystalline lens spherical aberration during simulated accommodation in a lens stretcher

Author

Ministerio de Ciencia e Innovación (España), National Institutes of Health (US), Consejo Superior de Investigaciones Científicas (España), European Research Council, Australian Research Council, Maceo Heilman, B., Manns, Fabrice, Castro, Alberto de, Durkee, H., Arrieta, E., Marcos, Susana, Parel, Jean Marie, Ministerio de Ciencia e Innovación (España), National Institutes of Health (US), Consejo Superior de Investigaciones Científicas (España), European Research Council, Australian Research Council, Maceo Heilman, B., Manns, Fabrice, Castro, Alberto de, Durkee, H., Arrieta, E., Marcos, Susana, and Parel, Jean Marie

Abstract

© 2015 The Association for Research in Vision and Ophthalmology, Inc. PURPOSE. The purpose of this study was to quantify accommodation-induced changes in the spherical aberration of cynomolgus monkey lenses. METHODS. Twenty-four lenses from 20 cynomolgus monkeys (Macaca fascicularis; 4.4-16.0 years of age; postmortem time 13.5±13.0 hours) were mounted in a lens stretcher. Lens spherical aberration was measured in the unstretched (accommodated) and stretched (relaxed) states with a laser ray tracing system that delivered 51 equally spaced parallel rays along 1 meridian of the lens over the central 6-mm optical zone. A camera mounted below the lens was used to measure the ray height at multiple positions along the optical axis. For each entrance ray, the change in ray height with axial position was fitted with a third-order polynomial. The effective paraxial focal length and Zernike spherical aberration coefficients corresponding to a 6-mm pupil diameter were extracted from the fitted values. RESULTS. The unstretched lens power decreased with age from 59.3±6 4.0 diopters (D) for young lenses to 45.7±6 3.1 D for older lenses. The unstretched lens shifted toward less negative spherical aberration with age, from -6.3±0.7 lm for young lenses to-5.0±0.5 lm for older lenses. The power and spherical aberration of lenses in the stretched state were independent of age, with values of 33.5±6 3.4 D and-2.6±0.5 lm, respectively. CONCLUSIONS. Spherical aberration is negative in cynomolgus monkey lenses and becomes more negative with accommodation. These results are in good agreement with the predicted values using computational ray tracing in a lens model with a reconstructed gradient refractive index. The spherical aberration of the unstretched lens becomes less negative with age.

Published
2015

131. Co-focused ultrasound and optical coherence elastography system for the study of age-related changes of biomechanical properties of crystalline lens in rabbit eyes

Author

Wu, Chen, additional, Han, Zhaolong, additional, Wang, Shang, additional, Li, Jiasong, additional, Singh, Manmohan, additional, Liu, Chih-hao, additional, Aglyamov, Salavat, additional, Emelianov, Stanislav, additional, Manns, Fabrice, additional, and Larin, Kirill V., additional

Published
2015
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134. Structural and biochemical characterization of the rat retina with combined Raman spectroscopy-spectral domain optical coherence tomography (RS-SDOCT)

Author

Patil, Chetan A., Kalkman, Jeroen, Faber, Dirk, Penn, John S., van Leeuwen, Ton G., Mahadevan-Jansen, Anita, Manns, Fabrice, Söderberg, Per G., Ho, Arthur, Biomedical Engineering and Physics, Amsterdam Gastroenterology Endocrinology Metabolism, Cancer Center Amsterdam, and Amsterdam Cardiovascular Sciences

Subjects
Retina, Materials science, genetic structures, medicine.diagnostic_test, business.industry, Retinal, Spectral domain, Rat retina, eye diseases, Characterization (materials science), chemistry.chemical_compound, symbols.namesake, medicine.anatomical_structure, Optics, chemistry, Optical coherence tomography, medicine, symbols, sense organs, Spectroscopy, Raman spectroscopy, business, Biomedical engineering
Abstract

Raman spectroscopy (RS) and Optical Coherence Tomography (OCT) are powerful tools for optical analysis of tissues with complimentary strengths. OCT excels and visualizing tissue microstructure while RS can relay tissue biochemical composition. Both instruments have significant potential to serve as valuable tools in non-invasive characterization of the rodent models of retinal disease. In this abstract we present the design and application of a common detector combined RS-OCT instrument for evaluating the morphological and biochemical differences in a rat model for oxygen induced retinopathy. Rat pups that have undergone a variable oxygen treatment are compared to rats raised in room air. Images and spectra collected at an age of 26 days postnatal demonstrate differences in both the thickness of the inner and outer nuclear layers, but also in the biochemical composition.

Published
2010

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