112 results on '"Boris Hermann"'
Search Results
2. An Outbreak of Wild Poliovirus in the Republic of Congo, 2010–2011
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Patel, Minal K., Konde, Mandy Kader, Didi-Ngossaki, Boris Hermann, Ndinga, Edouard, Yogolelo, Riziki, Salla, Mbaye, Shaba, Keith, Everts, Johannes, Armstrong, Gregory L., Daniels, Danni, Burns, Cara, Wassilak, Steve, Pallansch, Mark, and Kretsinger, Katrina
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- 2012
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3. Mapping diurnal changes in choroidal, Haller’s and Sattler’s layer thickness using 3-dimensional 1060-nm optical coherence tomography
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Susanne Binder, Behrooz Zabihian, Maximilian Gabriel, Farnusch Shams-Mafi, Siamak Ansari-Shahrezaei, Marieh Esmaeelpour, Wolfgang Drexler, and Boris Hermann
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Adult ,Male ,0301 basic medicine ,Materials science ,Adolescent ,Retinal Pigment Epithelium ,Sattler's layer ,Young Adult ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Imaging, Three-Dimensional ,0302 clinical medicine ,Nuclear magnetic resonance ,Optics ,Optical coherence tomography ,Nadir ,medicine ,Humans ,medicine.diagnostic_test ,Choroid ,business.industry ,Diurnal temperature variation ,Healthy subjects ,Reproducibility of Results ,Middle Aged ,Layer thickness ,Healthy Volunteers ,Sensory Systems ,Circadian Rhythm ,Ophthalmology ,030104 developmental biology ,medicine.anatomical_structure ,030221 ophthalmology & optometry ,Female ,Late afternoon ,sense organs ,business ,Algorithms ,Tomography, Optical Coherence - Abstract
To test the significance of diurnal changes in choroidal, Haller's and Sattler's layer thickness in healthy subjects using spatial analysis of three-dimensional (3D) 1060-nm optical coherence tomography (OCT) scans.Automatically generated choroidal, Haller's and Sattler's layer thickness maps were statistically analyzed for 19 healthy subjects at two time points (8 a.m. and 6 p.m.) that represent the currently proposed ChT peak and nadir. All subjects were imaged by high-speed 1060-nm OCT over a 36° × 36° field of view. Spatial distribution of layer thickness was analyzed using the Early Treatment Diabetic Retinopathy Study (ETDRS) grid.The choroid was significantly thicker at 8 a.m. than at 6 p.m. (p0,0125, paired t-test, Bonferroni correction). Diurnal variation of mean choroidal thickness (ChT) for all ETDRS subfields was 12 μm. Haller's layer thickness showed no significant diurnal variation (P0.0125), but Sattler's layer was thicker in the morning than in late afternoon (P0.0125).Our measurements indicate that diurnal ChT variation may exist, but is less relevant than previously proposed by studies using single location imaging. Sattler's layer shows diurnal variation in line with ChT.
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- 2017
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4. Mapping Retinal and Choroidal Thickness in Unilateral Nongranulomatous Acute Anterior Uveitis Using Three-Dimensional 1060-nm Optical Coherence Tomography
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Behrooz Zabihian, Farnusch Shams-Mafi, Marieh Esmaeelpour, Boris Hermann, Leopold Schmetterer, Wolfgang Drexler, Susanne Binder, Robert Kruger, and Maximilian Gabriel
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Adult ,Male ,medicine.medical_specialty ,genetic structures ,Response to therapy ,Retina ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Imaging, Three-Dimensional ,Optical coherence tomography ,Ophthalmology ,medicine ,Humans ,In patient ,Aged ,medicine.diagnostic_test ,business.industry ,Choroid ,Retinal ,Diabetic retinopathy ,Middle Aged ,medicine.disease ,Uveitis, Anterior ,eye diseases ,ACUTE ANTERIOR UVEITIS ,medicine.anatomical_structure ,chemistry ,Case-Control Studies ,Acute Disease ,030221 ophthalmology & optometry ,Female ,sense organs ,business ,Uveitis ,Tomography, Optical Coherence ,030215 immunology - Abstract
Purpose To analyze retinal thickness (RT) and choroidal thickness (ChT) changes in patients with unilateral nongranulomatous acute anterior uveitis (AAU) using three-dimensional (3D) 1060-nm optical coherence tomography (OCT). Methods Retinal and choroidal thickness maps were statistically analyzed for 24 patients with newly diagnosed unilateral AAU before therapy. A total of 17 patients were followed until resolution of inflammatory activity (twice in the first week, then weekly). Resolution occurred in all subjects within 6 weeks after the initial diagnosis. After resolution, thickness maps were again generated. All patients were imaged by high-speed spectral-domain (SD) 3D 1060-nm OCT over a 10 × 10-mm field of view. The spatial distribution of retinal and choroidal thickness was mapped and analyzed using the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Results The choroid was significantly thicker in eyes affected by AAU than in fellow eyes before therapy with a mean thickness difference of 37 ± 11.44 μm (mean ± SD, Bonferroni correction, α = 0.0125). Following therapy, ChT significantly decreased with a mean change of 24 ± 6.9 μm (mean ± SD, Bonferroni correction, α = 0.0125). There was no significant difference in RT between AAU and fellow eyes before therapy or in AAU eyes before and after therapy. Conclusions Eyes affected by AAU demonstrate an increase in ChT before and a subsequent decrease after therapy while retinal thickness seems unaltered by disease and therapy. ChT might be a useful biomarker in monitoring posterior involvement and response to therapy in patients with AAU.
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- 2017
5. Articulated dual modality photoacoustic and optical coherence tomography probe for preclinical and clinical imaging (Conference Presentation)
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Behrooz Zabihian, Jessika Weingast, Wolfgang Drexler, Hubert Pehamberger, Boris Hermann, Mengyang Liu, Paul C. Beard, Edward Z. Zhang, and Zhe Chen
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genetic structures ,medicine.diagnostic_test ,business.industry ,Computer science ,Photoacoustic imaging in biomedicine ,eye diseases ,Optics ,Optical coherence tomography ,Photoacoustic tomography ,medicine ,Dual modality ,sense organs ,Clinical imaging ,business ,Photoacoustic spectroscopy ,Polymer thin films ,Preclinical imaging - Abstract
The combination of photoacoustic tomography (PAT) with optical coherence tomography (OCT) has seen steady progress over the past few years. With the benchtop and semi-benchtop configurations, preclinical and clinical results have been demonstrated, paving the way for wider applications using dual modality PAT/OCT systems. However, as for the most updated semi-benchtop PAT/OCT system which employs a Fabry-Perot polymer film sensor, it is restricted to only human palm imaging due to the limited flexibility of the probe. The passband limit of the polymer film sensor further restricts the OCT source selection and reduces the sensitivity of the combined OCT system. To tackle these issues, we developed an articulated PAT/OCT probe for both preclinical and clinical applications. In the probe design, the sample arm of OCT sub-system and the interrogation part of the PAT sub-system are integrated into one compact unit. The polymer film sensor has a quick release function so that before each OCT scan, the sensor can be taken off to avoid the sensitivity drop and artefacts in OCT. The holding mechanism of the sensor is also more compact compared to previous designs, permitting access to uneven surfaces of the subjects. With the help of the articulated probe and a patient chair, we are able to perform co-registered imaging on human subjects on both upper and lower extremities while they are at rest positions. An increase in performance characteristics is also achieved. Patients with skin diseases are currently being recruited to test its clinical feasibility.
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- 2016
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6. All-optical highly sensitive broadband ultrasound sensor without any deformable parts for photoacoustic imaging
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Harald Sattmann, Wolfgang Rohringer, Stefan Preißer, Boris Hermann, Mengyang Liu, Zhe Chen, Balthasar Fischer, Stefan Zotter, and Wolfgang Drexler
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Frequency response ,Materials science ,business.industry ,Bandwidth (signal processing) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,010309 optics ,Interferometry ,Optics ,Confocal microscopy ,law ,0103 physical sciences ,Broadband ,Astronomical interferometer ,Optoelectronics ,Detection theory ,0210 nano-technology ,business ,Refractive index - Abstract
We present a novel akinetic optical ultrasound sensor, consisting of a rigid, fiber-coupled Fabry-P´erot interferometer (FPI) with a central opening. The sensing principle relies exclusively on the detection of pressure-induced changes of the refractive index in the liquid located between the cavity mirrors. This enables resonance-free, inherently linear signal detection over a large bandwidth. We demonstrate that the sensor allows to realize exceedingly low noise equivalent pressure (NEP) values of 2 Pa over a 20 MHz measurement bandwidth, while maintaining a large full field of view of 2,7mm × 1,3mm as well as a flat frequency response. Imaging tests on phantoms and biological tissue show the suitability of the XARION-sensor for optical resolution photoacoustic microscopy (OR-PAM) applications. Transparent in axial direction, the sensor facilitates the implementation of highly sensitive fast-scanning reflection-mode OR-PAM setups, as well as easy integration with other imaging modalities such as confocal microscopy or OCT.
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- 2016
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7. Transretinal degeneration in ageing human retina: a multiphoton microscopy analysis
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James Edwards Morgan, N. Garrahan, Michael P. Fautsch, Douglas H. Johnson, Michael E. Boulton, Boris Hermann, M. Hernandez, Y. Lei, Cardiff University, Mayo Clinic, University of Florida [Gainesville] (UF), and University of Wales College of Medicine
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Adult ,Male ,Retinal Ganglion Cells ,Retinal degeneration ,Pathology ,medicine.medical_specialty ,Adolescent ,Cell Count ,Biology ,Retina ,Article ,Imaging ,Young Adult ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,medicine ,Humans ,Outer nuclear layer ,Cellular Senescence ,Aged ,Aged, 80 and over ,Microscopy, Confocal ,medicine.disease ,eye diseases ,Sensory Systems ,Ophthalmology ,medicine.anatomical_structure ,Retinal ganglion cell ,Ageing ,Nerve Degeneration ,Inner nuclear layer ,030221 ophthalmology & optometry ,Female ,sense organs ,Neuron ,Cell aging ,030217 neurology & neurosurgery - Abstract
International audience; Abstract Purpose: Retinal cell remodelling has been reported as a consistent feature of ageing. However the degree to which this results in trans-retinal degeneration is unclear. To address this, we used multiphoton microscopy to quantify retinal degeneration in post-mortem human eyes of two age groups. Methods: Retinas from six young subjects (18-33 years old) and six aged subjects (74-90 years old) were prepared as wholemount preparation. All retina were stained with DAPI and imaged by multiphoton confocal microscopy to quantify neuron densities in the retinal ganglion cell layer (RGCL), inner nucleus layer (INL) and outer nucleus layer (ONL). Neurons were identified using automated cell identification. All retinas were imaged hydrated to minimise counting artefacts. Results: In both groups, 56% of the area within the central 4 mm eccentricity, and 27% of the area with eccentricity between 4 mm and 7 mm were imaged. Compared with young subjects, the peak RGCL neuron loss in the aged subjects was at 1mm eccentricity of 25.5%. In the INL and ONL, neuron density significantly decreased at 1-2 mm eccentricity (8.7%) and 0.5-4 mm eccentricity (15.6%) respectively (P < 0.05). The reduction in neuron density in the INL corresponded spatially to the region with the greatest neuron loss in the RGCL and ONL, Conclusions: This is the first study to correlate neurodegeneration in different populations of cells in the ageing retinas. Our data confirm that the greatest neuronal loss occurs in the RGCL and ONL in human ageing retinas, whereas the INL is relatively preserved.
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- 2010
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8. Comparison of UHR-OCT versus Stratus-OCT for definition of early retinal changes after intravitreal Bevacizumab (Avastin®) application in patients with AMD
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Susanne Binder, Shilla Lie, Stefan Hagen, Boris Hermann, Florian Zeiler, Boris Považay, Wolfgang Drexler, and Carl Glittenberg
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Retina ,medicine.medical_specialty ,genetic structures ,Bevacizumab ,medicine.diagnostic_test ,business.industry ,Retinal ,Macular degeneration ,medicine.disease ,eye diseases ,Surgery ,Ophthalmology ,chemistry.chemical_compound ,medicine.anatomical_structure ,Optical coherence tomography ,chemistry ,medicine ,In patient ,sense organs ,Intravitreal bevacizumab ,business ,After treatment ,medicine.drug - Abstract
PURPOSE: To investigate and demonstrate early structural changes of the retina/pigmentepithelial/choriocapillaris (RPECC) complex before and 10 ± 3 days after intravitreal application of bevacizumab (Avastin®) in patients with neovascular age related macular degeneration (nAMD) by comparison of standard Stratus Optical Coherence Tomography (S-OCT) and Ultra High Resolution (UHR-OCT) imaging systems. METHODS: Six patients with nAMD were examined in a consecutive case series with UHR-OCT and Stratus OCT one day before and 10 ± 3 days after intravitreal application of 1.25 mg (0.125 ml) bevacizumab (Avastin®). Maximum central retinal thickness (CRT) was measured with the retinal thickness program and calliper measuring function of S-OCT and by the measuring tool of Adobe Photoshop 5.0 in UHR-OCT pictures. RESULTS: In three of six cases residual fluid after treatment was only visible with UHR-OCT but not with the S-OCT. A decrease of maximum CRT could be shown in all cases in UHR-OCT pictures but only in half of the cases (6/3) in S-OCT pictures. In 2/6 cases vitreoretinal adhesions were demonstrable with UHR-OCT but not seen with the S-OCT, irregularities in the photoreceptor layer could be revealed clearly by UHR-OCT in 2/6 cases. CONCLUSION: After anti-VEGF treatment, UHR–OCT gives more accurate information about residual fluid and intraretinal damage than S-OCT and offers more precise measurements of maximum CRT. These factors may influence further decision of therapy and give us a better explanation and correlation with unsatisfactory visual acuities than with the S-OCT.
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- 2009
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9. Wide-Field Optical Coherence Tomography of the Choroid In Vivo
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Boris Povazay, Boris Hermann, Bernd Hofer, Wolfgang Drexler, Vedran Kajić, Elizabeth Simpson, and Thomas Bridgford
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Adult ,Materials science ,genetic structures ,Retina ,Young Adult ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Imaging, Three-Dimensional ,Optics ,Optical coherence tomography ,Image Processing, Computer-Assisted ,medicine ,Humans ,Pixel ,medicine.diagnostic_test ,Choroid ,business.industry ,Retinal ,Anatomy ,eye diseases ,Sensory Systems ,Sclera ,Ophthalmology ,medicine.anatomical_structure ,chemistry ,Optic nerve ,Feasibility Studies ,sense organs ,Tomography ,Artifacts ,business ,Tomography, Optical Coherence - Abstract
PURPOSE To demonstrate high-speed, high axial resolution optical coherence tomography (OCT) at 1060 nm with penetration to the sclera. The clinical feasibility of dense, high-speed sampling for higher levels of detail at the macula and optic nerve head is explored with respect to motion artifacts. METHODS A three-dimensional (3D) OCT system making use of a high-speed camera operating at 47,000 depth scans/s was developed. The 1010- to 1080-nm wavelength band leads to 6.7 microm effective axial resolution and enables the acquisition of retinal and choroidal 130 Megavoxel volumes of human subjects within 7 seconds. Motion artifacts were reduced by numeric postprocessing techniques. RESULTS Drift motion artifacts could be suppressed within fields up to 38 degrees x 38 degrees (approximately 1 cm(2)) using acquisition speeds of up to 74 frames/s at 512 x 512 pixel/frame. This isotropic OCT sampling of the human retina in vivo allowed reconstruction of the retinal microvasculature solely on vessel reflectivity, without the use of contrast agents, and revealed three interconnected capillary meshworks. Simultaneously in the choroid, the structure of the choriocapillaris, Sattler's layer, and Haller's layer were differentiated, and the choroidal-scleral interface was clearly delineated in densely sampled narrow- and wide-angle scans (>38 degrees). At the optic nerve head, the 3D fine structure of the lamina cribrosa and the circle of Zinn-Haller were visualized. CONCLUSIONS OCT almost centered within the 1060-nm water transmission window significantly profits from lower scattering and allows investigation of the retina and choroid at an unprecedented combination of penetration and high speed at high resolution and may provide superior clinical feasibility to commercial 800-nm devices.
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- 2008
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10. Fördert die chronische papillovitreale Traktion die Progredienz einer Optikusatrophie?
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Boris Považay, Carl Glittenberg, Wolfgang Drexler, Florian Zeiler, Susanne Binder, and Boris Hermann
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Ophthalmology - Abstract
HINTERGRUND: Im Verlauf der hinteren Glaskorperabhebung kommt es neben den in der Literatur ausfuhrlich beschriebenen makularen und peripheren Glaskorpertraktionen auch zu Traktionen an der Papille des N.opticus. Diese papillovitrealen Traktionsstrange konnen durch Zug und Dehnungsbelastung auf die retinale Nervenfaserschicht den Verlauf einer Optikusatrophie beinflussen. PATIENTEN UND METHODE: Ein 78-jahriger Patient leidet an einer progredienten Optikusatrophie am linken Auge trotz normaler Augendruckwerte. Seit zwei Jahren verschlechtern sich Visus und Gesichtsfeldbefund kontinuierlich. Klinisch und in den Untersuchungen mittels Optischer Koharenz Tomographie (OCT) zeigten sich deutliche papillovitreale Traktionsstrange vor allem im superior, nasalen Bereich der Papille. RESULTATE: Die papillovitrealen Traktionsstrange konnten im OCT eindeutig dargestellt werden. Im Ultrahigh Resolution OCT (UHR-OCT) zeigten sich spannungsbedingte, cystische Strukturen in der Ganglienzell- und Nervenfaserschicht an den Stellen der starksten Anhaftung der Traktionsstrange. Bei konstantem Fernvisus verringerte sich der Nahvisus von 0.3 logRAD auf 0.9 logRAD innerhalb eines Jahres. Im Gesichtsfeld (GF) bildete sich ein deutlich progredienter Ausfall der beiden unteren Quadranten intermediar, dem starksten Anhaftungsbereich der Traktionsstrange entsprechend. DISKUSSION: Der progrediente Gesichtsfeldausfall und die Visusverschlechterung sprechen fur eine chronische Schadigung des N.opticus an der Papille durch die papillovitrealen Traktionsstrange. Durch die von den Traktionsstrangen ausgeubten Zugkrafte kommt es zu einer Elongation, Dehnung und zu einer Abnahme im Axondurchmesser. Die anterograde und retrograde axoplasmatische Leitung wird gestort und die Progredienz der Optikusatrophie gefordert. Die Zugbelastung an den Aa.ciliares posteriores fuhrt zu einer Minderperfusion die sich in einer deutlichen Abblassung der Papille zeigt.
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- 2007
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11. Dreidimensionale Rekonstruktion von Schichtbildaufnahmen der Netzhaut
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Florian Zeiler, Boris Považay, C. I. Falkner, Wolfgang Drexler, Carl Glittenberg, Susanne Binder, and Boris Hermann
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Ophthalmology - Abstract
ZIELSETZUNG: Die Entwicklung eines neuen Darstellungssystems fur die dreidimensionale Visualisierung von Schichtbildaufnahmen in der Augenheilkunde. Im Speziellen, ein System das B-Mode-Scan-Datensatze von einer ultrahochauflosenden optischen Koharenztomographie-untersuchung als plastische dreidimensionale Objekte darstellen kann. METHODE: Im Rendering- und Raytracing-Programm Cinema 4D XL 9.102 Studio Bundle (Maxon Computer GmbH, Friedrichsburg, Deutschland) wurden mehrere "Subroutinen" programmiert die Schichtbildaufnahmen zu dreidimensionalen Darstellungen verarbeiten konnen. Es wurden von Patienten mit verschiedenen Netzhauterkrankungen ultrahochauflosende optische Koharenztomographien aufgenommen, und mit den programmierten "Subroutinen" zu dreidimensionalen Objekten weiterverarbeitet. Alle ultrahochauflosenden optischen Koharenztomographie-Untersuchungen wurden mit einem Ultrabreitband (160 nm) Titan:Saphire basierten Femtosecunden-Laser-System (INTEGRAL, Femtolasers Productions GmbH, Vienna, Austria) mit einer axialen Auflosung von 3 μm durchgefuhrt. RESULTATE: Es wurde ein neues dreidimensionales Darstellungssystem fur Schichtbildaufnahmen in der Augenheilkunde entwickelt das eine sehr plastische Darstellung von physiologischen und pathologischen Strukturen in der Netzhaut erlaubt. Das System zeichnet sich zusatzlich durch eine hohe Interaktivitat sowie durch eine grose Anpassungsfahigkeit aus. SCHLUSSFOLGERUNG: Das neue Darstellungssystem erlaubt die Visualisierung von physiologischen und pathologischen Strukturen der Netzhaut in einer Art und Weise, die uns neue Einsicht uber deren Morphologien und Entwicklungen geben wird.
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- 2007
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12. In vivo dual-modality photoacoustic and optical coherence tomography imaging of human dermatological pathologies
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Hubert Pehamberger, Mengyang Liu, Edward Z. Zhang, Jessika Weingast, Wolfgang Drexler, Behrooz Zabihian, Paul C. Beard, and Boris Hermann
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Pathology ,medicine.medical_specialty ,Dermatoscopy ,medicine.diagnostic_test ,business.industry ,Photoacoustic imaging in biomedicine ,Magnetic resonance imaging ,Human skin ,Atomic and Molecular Physics, and Optics ,Article ,Functional imaging ,Optical coherence tomography ,In vivo ,medicine ,business ,Preclinical imaging ,Biotechnology ,Biomedical engineering - Abstract
Vascular abnormalities serve as a key indicator for many skin diseases. Currently available methods in dermatology such as histopathology and dermatoscopy analyze underlying vasculature in human skin but are either invasive, time-consuming, and laborious or incapable of providing 3D images. In this work, we applied for the first time dual-modality photoacoustic and optical coherence tomography that provides complementary information about tissue morphology and vasculature of patients with different types of dermatitis. Its noninvasiveness and relatively short imaging time and the wide range of diseases that it can detect prove the merits of the dual-modality imaging system and show the great potential of its clinical use in the future.
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- 2015
13. Evaluation of speckle reduction with denoising filtering in optical coherence tomography for dermatology
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Maria J. Ledesma-Carbayo, Andres Santos, Behrooz Zabihian, Juan J. Gómez-Valverde, Pedro Guerra, Juan E. Ortuño, José L. Rubio-Guivernau, Boris Hermann, and Wolfgang Drexler
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Artifact (error) ,medicine.diagnostic_test ,business.industry ,Noise reduction ,Speckle noise ,Filter (signal processing) ,Speckle pattern ,Wavelet ,Optical coherence tomography ,medicine ,Computer vision ,Artificial intelligence ,Optical filter ,business ,Mathematics - Abstract
Optical Coherence Tomography (OCT) has shown a great potential as a complementary imaging tool in the diagnosis of skin diseases. Speckle noise is the most prominent artifact present in OCT images and could limit the interpretation and detection capabilities. In this work we evaluate various denoising filters with high edge-preserving potential for the reduction of speckle noise in 256 dermatological OCT B-scans. Our results show that the Enhanced Sigma Filter and the Block Matching 3-D (BM3D) as 2D denoising filters and the Wavelet Multiframe algorithm considering adjacent B-scans achieved the best results in terms of the enhancement quality metrics used. Our results suggest that a combination of 2D filtering followed by a wavelet based compounding algorithm may significantly reduce speckle, increasing signal-to-noise and contrast-to-noise ratios, without the need of extra acquisitions of the same frame.
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- 2015
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14. Hybrid ultrahigh resolution optical coherence / photoacoustic microscopy
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Wolfgang Weninger, Nicole Schmitner, Boris Hermann, Wolfgang Drexler, Dirk Meyer, Mengyang Liu, and Barbara Maurer
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Materials science ,medicine.diagnostic_test ,business.industry ,Laser ,law.invention ,Wavelength ,Optics ,Ultrahigh resolution ,Optical coherence tomography ,law ,Microscopy ,Medical imaging ,medicine ,business ,Preclinical imaging ,Coherence (physics) - Abstract
We present an ultrahigh resolution dual modality optical resolution photoacoustic microsopy (OR-PAM) and spectral domain optical coherence microscopy (SD-OCM) system. The ultrahigh sub-micron lateral resolution is provided by the high numerical aperture of the objective lens used while the ultrahigh axial resolution is provided by the broadband OCT laser that covers 107 nm with a central wavelength of 840 nm. The synchronized simultaneous acquisition for the two modalities is achieved using a 40MHz FPGA. 2D-scanning is realized by two orthogonal translation stages (PI, 400 nm resolution). The transversal resolution of the system is 0.5 μm, the axial resolutions are 30 μm (PAM) and 4 μm (OCM), respectively. The values have been determined experimentally using nanospheres (diameter 10-200nm). For a demonstration of the imaging capability we present images from thin slices of different biological samples as well as in vivo imaging in the zebrafish embryo.
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- 2015
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15. Ultrahigh resolution optical coherence tomography of the monkey fovea. Identification of retinal sublayers by correlation with semithin histology sections
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Christian Schubert, Wolfgang Drexler, Peter K. Ahnelt, Angelika Unterhuber, Harald Sattmann, A. Cowey, Boris Hermann, James Edwards Morgan, and E.M. Anger
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Fovea Centralis ,Materials science ,genetic structures ,Optic Disk ,Normalization (image processing) ,Retina ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Optics ,Optical coherence tomography ,medicine ,Animals ,medicine.diagnostic_test ,business.industry ,Resolution (electron density) ,Retinal ,Histology ,eye diseases ,Sensory Systems ,Macaca fascicularis ,Ophthalmology ,medicine.anatomical_structure ,chemistry ,Ultrahigh resolution ,sense organs ,Tomography ,Artifacts ,business ,Tomography, Optical Coherence ,Photoreceptor Cells, Vertebrate - Abstract
Optical coherence tomography (OCT) has become an established diagnostic tool for the clinical assessment of retinal pathology but correlation of acquired signals with retinal substructures has often been ambiguous. In the monkey retina we have now obtained ultrahigh resolution (UHR) OCT images with 1.4 microm axial x 3 microm transverse resolution from perfusion-fixed eye cups of Macaca fascicularis and optimized the identification of retinal anatomy by correction of spatial artefacts in correlated histology. After resin embedding, serial semithin sections were obtained that corresponded to OCT transects. The direct overlay of features identified in histological sections with corresponding OCT locations was limited by non-linear tissue shrinkage due to dehydration and sectioning stress. In the present study, these misalignments were further corrected by using polygonal spline morphing based on corresponding unequivocal landmarks. The geometric normalization then allowed detailed comparison of both profiles including delicate sublayers of photoreceptor inner- and outer segments. Such correlation will facilitate the extraction of structural information from in vivo ultrahigh resolution OCT images in clinical and experimental applications.
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- 2004
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16. Advances in broad bandwidth light sources for ultrahigh resolution optical coherence tomography
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James Edwards Morgan, Ralf Menzel, Peter K. Ahnelt, Harald Sattmann, Herbert A. Reitsamer, Boris Hermann, C. Schubert, Angelika Unterhuber, Boris Povazay, Herbert Budka, Tuan Le, M. Seefeld, A. Cowey, Matthias Preusser, Kostadinka Bizheva, Wolfgang Drexler, and Andreas Stingl
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Materials science ,Light ,genetic structures ,Sensitivity and Specificity ,Retina ,law.invention ,Optics ,Optical coherence tomography ,law ,Neoplasms ,medicine ,Animals ,Fiber Optic Technology ,Humans ,Radiology, Nuclear Medicine and imaging ,Penetration depth ,Image resolution ,Brain Diseases ,Ganglia, Sympathetic ,Radiological and Ultrasound Technology ,medicine.diagnostic_test ,business.industry ,Lasers ,Equipment Design ,Image Enhancement ,Laser ,Rats ,Macaca fascicularis ,Wavelength ,Full width at half maximum ,Sapphire ,Feasibility Studies ,sense organs ,Tomography ,business ,HT29 Cells ,Tomography, Optical Coherence - Abstract
Novel ultra-broad bandwidth light sources enabling unprecedented sub-2 microm axial resolution over the 400 nm-1700 nm wavelength range have been developed and evaluated with respect to their feasibility for clinical ultrahigh resolution optical coherence tomography (UHR OCT) applications. The state-of-the-art light sources described here include a compact Kerr lens mode locked Ti:sapphire laser (lambdaC = 785 nm, delta lambda = 260 nm, P(out) = 50 mW) and different nonlinear fibre-based light sources with spectral bandwidths (at full width at half maximum) up to 350 nm at lambdaC = 1130 nm and 470 nm at lambdaC = 1375 nm. In vitro UHR OCT imaging is demonstrated at multiple wavelengths in human cancer cells, animal ganglion cells as well as in neuropathologic and ophthalmic biopsies in order to compare and optimize UHR OCT image contrast, resolution and penetration depth.
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- 2004
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17. Speckle reduction process based on digital filtering and wavelet compounding in optical coherence tomography for dermatology
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Boris Hermann, José L. Rubio-Guivernau, Behrooz Zabihian, Maria J. Ledesma-Carbayo, Wolfgang Drexler, Juan J. Gómez Valverde, Andres Santos, Juan E. Ortuño, and Pedro Guerra
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Artifact (error) ,medicine.diagnostic_test ,Noise (signal processing) ,Image quality ,business.industry ,Computer science ,Noise reduction ,Speckle noise ,Speckle pattern ,Wavelet ,Optical coherence tomography ,medicine ,Computer vision ,Artificial intelligence ,business - Abstract
Optical Coherence Tomography (OCT) has shown a great potential as a complementary imaging tool in the diagnosis of skin diseases. Speckle noise is the most prominent artifact present in OCT images and could limit the interpretation and detection capabilities. In this work we propose a new speckle reduction process and compare it with various denoising filters with high edge-preserving potential, using several sets of dermatological OCT B-scans. To validate the performance we used a custom-designed spectral domain OCT and two different data set groups. The first group consisted in five datasets of a single B-scan captured N times (with N
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- 2015
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18. Dual modality optical coherence and whole-body photoacoustic tomography imaging of chick embryos in multiple development stages
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Paul C. Beard, Michelle Gabriele Sandrian, Bernhard Baumann, Edward Z. Zhang, Wolfgang Drexler, Boris Hermann, Barbara Maurer, Mengyang Liu, Wolfgang Weninger, Angelika Unterhuber, and Behrooz Zabihian
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Pathology ,medicine.medical_specialty ,animal structures ,medicine.diagnostic_test ,genetic structures ,Biology ,Chick embryos ,In ovo ,Atomic and Molecular Physics, and Optics ,eye diseases ,Article ,Optical coherence tomography ,Light sheet fluorescence microscopy ,Photoacoustic tomography ,embryonic structures ,medicine ,Dual modality ,Preclinical imaging ,Biotechnology ,Coherence (physics) ,Biomedical engineering - Abstract
Chick embryos are an important animal model for biomedical studies. The visualization of chick embryos, however, is limited mostly to postmortem sectional imaging methods. In this work, we present a dual modality optical imaging system that combines swept-source optical coherence tomography and whole-body photoacoustic tomography, and apply it to image chick embryos at three different development stages. The explanted chick embryos were imaged in toto with complementary contrast from both optical scattering and optical absorption. The results serve as a prelude to the use of the dual modality system in longitudinal whole-body monitoring of chick embryos in ovo.
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- 2014
19. In vivo spectroscopic photoacoustic tomography imaging of a far red fluorescent protein expressed in the exocrine pancreas of adult zebrafish
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Michelle G. Sandrian, Willi Salvenmoser, Wolfgang Drexler, Behrooz Zabihian, Mengyang Liu, Nicole Schmitner, Boris Hermann, and Dirk Meyer
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medicine.diagnostic_test ,biology ,Chemistry ,business.industry ,Near-infrared spectroscopy ,biology.organism_classification ,Fluorescence ,Green fluorescent protein ,Optics ,Optical coherence tomography ,In vivo ,Microscopy ,medicine ,Fluorescence microscope ,Biophysics ,business ,Zebrafish - Abstract
Fluorescent proteins brought a revolution in life sciences and biological research in that they make a powerful tool for researchers to study not only the structural and morphological information, but also dynamic and functional information in living cells and organisms. While green fluorescent proteins (GFP) have become a common labeling tool, red-shifted or even near infrared fluorescent proteins are becoming the research focus due to the fact that longer excitation wavelengths are more suitable for deep tissue imaging. In this study, E2-Crimson, a far red fluorescent protein whose excitation wavelength is 611 nm, was genetically expressed in the exocrine pancreas of adult zebrafish. Using spectroscopic all optical detection photoacoustic tomography, we mapped the distribution of E2-Crimson in 3D after imaging the transgenic zebrafish in vivo using two different wavelengths. With complementary morphological information provided by imaging the same fish using a spectral domain optical coherence tomography system, the E2-Crimson distribution acquired from spectroscopic photoacoustic tomography was confirmed in 2D by epifluorescence microscopy and in 3D by histology. To the authors’ knowledge, this is the first time a far red fluorescent protein is imaged in vivo by spectroscopic photoacoustic tomography. Due to the regeneration feature of zebrafish pancreas, this work preludes the longitudinal studies of animal models of diseases such as pancreatitis by spectroscopic photoacoustic tomography. Since the effective penetration depth of photoacoustic tomography is beyond the transport mean free path length, other E2-Crimson labeled inner organs will also be able to be studied dynamically using spectroscopic photoacoustic tomography.
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- 2014
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20. Optical detection of photoacoustic waves using phase sensitive low-coherence interferometry
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M. Gabriele-Sandrian, Boris Povazay, Bernd Hofer, Wolfgang Drexler, and Boris Hermann
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Materials science ,medicine.diagnostic_test ,business.industry ,Physics::Medical Physics ,Astrophysics::Instrumentation and Methods for Astrophysics ,Physics::Optics ,Acoustic wave ,Photoacoustic Doppler effect ,Interferometry ,Transducer ,Optics ,Optical coherence tomography ,medicine ,Ultrasonic sensor ,business ,Photoacoustic spectroscopy ,Coherence (physics) - Abstract
Detection of acoustic waves is the cornerstone of photoacoustic tomography (PAT). Detection has conventionally been performed mechanically using ultrasonic transducers, or optically by interferometric techniques. We propose an interferometric detection scheme using low coherence interferometry (LCI) and discuss the challenges, advantages and limitations of applying this technique to photoacoustics.
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- 2012
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21. Mapping choroidal and retinal thickness variation in Type 2 diabetes using three-dimensional 1060-nm optical coherence tomography
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Boris Považay, N. J. L. Sheen, Vedran Kajić, Wolfgang Drexler, Rachel Valerie North, Bernd Hofer, Sarah L Hale, Boris Hermann, and Marieh Esmaeelpour
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Adult ,Male ,medicine.medical_specialty ,genetic structures ,Fundus Oculi ,Fundus (eye) ,Retina ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Optical coherence tomography ,Ophthalmology ,Diabetes mellitus ,medicine ,Humans ,Macular edema ,Aged ,2. Zero hunger ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Choroid ,Retinal ,Diabetic retinopathy ,Middle Aged ,medicine.disease ,R1 ,eye diseases ,3. Good health ,medicine.anatomical_structure ,chemistry ,Diabetes Mellitus, Type 2 ,030221 ophthalmology & optometry ,Maculopathy ,Optometry ,Female ,RE ,sense organs ,business ,030217 neurology & neurosurgery ,Tomography, Optical Coherence - Abstract
To map choroidal (ChT) and retinal thickness (RT) in healthy subjects and patients with diabetes with and without maculopathy using three dimensional 1060-nm optical coherence tomography (3D-1060nm-OCT).Sixty-three eyes from 42 diabetic subjects (41-82 years of age; 11 females) grouped according to a custom scheme using Early Treatment Diabetic Retinopathy Study definitions for pathology within 1 disc-diameter of fovea (without pathology [NDR], microaneurysms [M1], exudates [M2], clinically significant macular edema [CSME]) and 16 eyes from 16 healthy age matched subjects (38-79 years of age; 11 females) were imaged by 3D-1060nm-OCT performed over a 36° × 36° field of view. Axial length, 45° fundus photographs, body mass index, plasma glucose, and blood pressure measurements were recorded. The ChT at the subfoveal location and ChT maps between RPE and the choroidal-scleral interface were generated and statistically analyzed.RT maps show thinning in the NDR group but an increase in thickness with increasing maculopathy in the temporal and central regions (unpaired t-test; P0.05). ChT mapping of all diabetic patients revealed central and inferior thinning compared to healthy eyes (unpaired t-test; P0.001). Subfoveal ChT (mean ± SD) for healthy eyes was 327 ± 74 μm, which was significantly thicker than all diabetic groups (214 ± 55 μm for NDR, 208 ± 49 μm for M1, 205 ± 54 μm for M2, and 211 ± 76 μm for CSME (ANOVA P0.001; Tukey P0.001).3D-1060nm-OCT has shown that the central choroid is thinner in all type 2 diabetic eyes regardless of disease stage. The choroidal thinning may exceed the magnitude of possible choriocapillaris atrophy. In contrast to the conventional assessment of pathologic thickness change in several locations, thickness maps allow investigation of the choroid over the extent of affected areas.
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- 2011
22. Fast dispersion encoded full range OCT for retinal imaging at 800 nm and 1060 nm
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Bernd Hofer, Ling Wang, Gerald Matz, Sara Rey, Angelika Unterhuber, Boris Považay, Wolfgang Drexler, and Boris Hermann
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Optical fiber ,Materials science ,Spectrometer ,medicine.diagnostic_test ,business.industry ,Signal ,law.invention ,Wavelength ,Optics ,Sampling (signal processing) ,Optical coherence tomography ,law ,Dispersion (optics) ,medicine ,business ,Retinal scan - Abstract
The dispersion mismatch between sample and reference arm in frequency-domain OCT can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. We propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed for in vivo retinal tomograms at 800 nm. Best results have been achieved with about 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves an average suppression ratio of 55 dB and converges within 5 to 10 iterations. The processing time on non-dedicated hardware was 5 to 10 seconds for tomograms with 512 depth scans and 4096 sampling points per depth scan. Application of DEFR to the more challenging 1060 nm wavelength region is demonstrated by introducing an additional optical fibre in the sample arm.
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- 2011
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23. Multimodal optical coherence/photoacoustic tomography of skin
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Paul C. Beard, Carl Glittenberg, Bernd Hofer, Jan Laufer, Boris Hermann, Edward Z. Zhang, Aneesh Alex, Boris Považay, and Wolfgang Drexler
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Multimodal imaging ,Materials science ,medicine.diagnostic_test ,business.industry ,Laser ,law.invention ,Interferometry ,Optics ,Planar ,Optical coherence tomography ,law ,Photoacoustic tomography ,medicine ,Transmittance ,business ,Coherence (physics) - Abstract
A novel non-invasive in vivo multimodal optical coherence tomography (OCT)/photoacoustic tomography (PAT) imaging system capable of obtaining structural and functional information simultaneously has been demonstrated in skin. A 1060 nm OCT system acquiring 47k depth-scans/s with ~ 7 μm axial and ~ 20 μm transverse resolutions has been incorporated into a backward-mode PA system based on a planar, optically-transparent Fabry-Perot interferometer (FPI) sensor. In this study, the excitation wavelength was set to 670 nm and a focused laser beam at 1550 nm was used as the sensor interrogation beam. OCT and PAT images were obtained sequentially and the coregistered images were combined to form the final 3D image. OCT/PAT images obtained in vivo from the skin of a hairless mouse and human palmar skin demonstrated the ability of this multimodal imaging system to provide complementary structural and functional information from deeper depths with increased contrast.
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- 2011
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24. Artefact reduction for cell migration visualization using spectral domain optical coherence tomography
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Boris Hermann, Gerald Matz, Kate Powell, Bernd Hofer, Sara Rey, Vedran Kajić, Alexandre R. Tumlinson, Boris Povazˇay, and Wolfgang Drexler
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Retinal Ganglion Cells ,Microscope ,Materials science ,General Physics and Astronomy ,Image processing ,02 engineering and technology ,01 natural sciences ,Retinal ganglion ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Cell Line ,010309 optics ,Optics ,Optical coherence tomography ,law ,Cell Movement ,0103 physical sciences ,Microscopy ,medicine ,Image noise ,Image Processing, Computer-Assisted ,General Materials Science ,Dictyostelium ,medicine.diagnostic_test ,business.industry ,General Engineering ,General Chemistry ,021001 nanoscience & nanotechnology ,body regions ,sense organs ,Tomography ,0210 nano-technology ,business ,Artifacts ,Tomography, Optical Coherence ,Coherence (physics) - Abstract
Visualization of cell migration during chemotaxis using spectral domain optical coherence tomography (OCT) requires non-standard processing techniques. Stripe artefacts and camera noise floor present in OCT data prevent detailed computer-assisted reconstruction and quantification of cell locomotion. Furthermore, imaging artefacts lead to unreliable results in automated texture based cell analysis. Here we characterize three pronounced artefacts that become visible when imaging sample structures with high dynamic range, e.g. cultured cells: (i) time-varying fixed-pattern noise; (ii) stripe artefacts generated by background estimation using tomogram averaging; (iii) image modulations due to spectral shaping. We evaluate techniques to minimize the above mentioned artefacts using an 800 nm optical coherence microscope. Effect of artefact reduction is shown exemplarily on two cell cultures, i.e. Dictyostelium on nitrocellulose substrate, and retinal ganglion cells (RGC-5) cultured on a glass coverslip. Retinal imaging also profits from the proposed processing techniques. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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- 2010
25. Three-Dimensional 1060-nm OCT: Choroidal thickness maps in normal subjects and improved posterior segment visualization in cataract patients
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Bernd Hofer, Boris Povazay, Boris Hermann, Nicholas John Leighton Sheen, K. Kapoor, Marieh Esmaeelpour, Wolfgang Drexler, Kajic, and Rachel Valerie North
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Adult ,Male ,Aging ,medicine.medical_specialty ,Biometry ,genetic structures ,Posterior pole ,Fundus (eye) ,Cataract ,Young Adult ,03 medical and health sciences ,Imaging, Three-Dimensional ,0302 clinical medicine ,Signal strength ,Reference Values ,Ophthalmology ,medicine ,Medical imaging ,Humans ,Diagnostic biomarker ,Aged ,030304 developmental biology ,Aged, 80 and over ,0303 health sciences ,Retinal pigment epithelium ,Anthropometry ,Choroid ,business.industry ,Organ Size ,Middle Aged ,eye diseases ,Posterior segment of eyeball ,medicine.anatomical_structure ,030221 ophthalmology & optometry ,Female ,RE ,Tomography ,sense organs ,business ,Tomography, Optical Coherence - Abstract
Purpose. To evaluate the performance and potential clinical role of three-dimensional (3D) 1060-nm OCT by generating choroidal thickness (ChT) maps in patients of different ages with different degrees of ametropia and axial lengths and to investigate the effect of cataract grade on OCT retinal imaging quality. \ud \ud Methods. Axial lengths (ALs) and 45° fundus photographs were acquired from 64 eyes (34 healthy subjects, 19 to 80 years, ametropia +3 to −10 D). 3D 1060-nm OCT was performed over a 36° × 36° field of view with ∼7-μm axial resolution and up to 70 frames/s (512 A-scans/frame). ChT maps between retinal pigment epithelium and the choroidal–scleral interface, were generated and statistically analyzed. A further 30 eyes (19 subjects), with cataracts assessed with the LOCS III scale, were imaged with 3D 1060-nm OCT and 800-nm OCT, and visualization of the posterior segment was compared qualitatively. \ud \ud Results. In 64 eyes, ChT maps displayed a thickness decrease with increasing AL. Subfoveal ChT was 315 ± 106 μm (mean ± SD), negatively correlated with AL (R2 = −0.47, P < 0.001). Averaged ChT maps of eyes with AL < 23.39 mm showed an increased ChT in an area ∼1500 μm inferior, compared with subfoveal ChT. Eyes with AL > 24.5 mm showed a larger variation and a thicker ChT superiorly than inferiorly. Reduced signal strength in cataractous eyes was found in 65% of the 800-nm OCT images, but in only 10% of the 1060-nm OCT images. \ud \ud Conclusions. The imaging performance of 3D 1060-nm OCT is unique, producing maps that show the variation in ChT over the entire field of view, in relation to axial length. This imaging system has the potential of visualizing a novel clinical diagnostic biomarker. Compared with 800-nm OCT, it provides superior visualization of the posterior pole in cataractous eyes.
- Published
- 2010
26. Topography of neuron loss in the retinal ganglion cell layer in human glaucoma
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Douglas H. Johnson, Y. Lei, N. Garrahan, Michael E. Boulton, Michael P. Fautsch, M. Hernandez, James Edwards Morgan, Boris Hermann, Cardiff University, Mayo Clinic, Northwestern University [Evanston], and University of Florida [Gainesville] (UF)
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Retinal Ganglion Cells ,Intraocular pressure ,medicine.medical_specialty ,genetic structures ,Population ,Glaucoma ,Cell Count ,Cell Communication ,Biology ,Article ,Retina ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,0302 clinical medicine ,Ophthalmology ,medicine ,Humans ,education ,Aged ,Aged, 80 and over ,education.field_of_study ,Cell Death ,Retinal ,Middle Aged ,medicine.disease ,Sensory Systems ,eye diseases ,Visual field ,Ganglion ,medicine.anatomical_structure ,Microscopy, Fluorescence ,chemistry ,Retinal ganglion cell ,Case-Control Studies ,030221 ophthalmology & optometry ,Degeneration ,sense organs ,030217 neurology & neurosurgery - Abstract
Aim: To determine if retinal ganglion cell (RGC) loss influences the loss of surrounding RGCs to generate clustered patterns of cell death in human glaucoma. It is hypothesised that retinal ganglion cell loss accelerates the loss of surrounding cells to generate, at a local, cellular scale, clustered patterns of retinal of RGC death. The absence of these interactions would result in a diffuse pattern RGC loss. Method: Six glaucomatous retinas (67–83 years old) and six age-matched control retinas (61–89 years old) were prepared as wholemounts and stained by 4′,6-diamidino-2-phenylindole (DAPI) solution (3 μg/ml in PBS). An area corresponding to central 14° of the visual field was imaged. The nearest-neighbour distribution was determined for cells in both normal and glaucomatous RGCL. Results: Clustered RGC loss in human glaucoma was observed on a background of diffuse loss. The mean nearest-neighbour distance (NND) of the glaucomatous retinas was significantly higher than with controls (p
- Published
- 2009
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27. Spectroscopy in single and double layered weakly scattering phantoms using frequency domain optical coherence tomography
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Bernd Hofer, Christoph Meier, Boris Hermann, Boris Považay, and Wolfgang Drexler
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medicine.diagnostic_test ,Spectrometer ,Scattering ,business.industry ,Chemistry ,Wavelength ,Optics ,Optical coherence tomography ,Frequency domain ,Attenuation coefficient ,Chromatic aberration ,medicine ,business ,Spectroscopy - Abstract
In this study, depth resolved measurements of absorption profiles in the wavelength range of 800 nm with a bandwidth of 140 nm are demonstrated using high speed spectroscopic frequency domain OCT (SOCT). With proper calibration, SOCT is able to extract absolute, depth resolved absorption profiles over the whole wavelength range at once without the need of tuning and performing measurements at single wavelengths sequentially. In addition, high acquisition speed in excess of 20 kHz allows to measure absorption dynamics with 50 µs time resolution, which might be useful for the investigation of pharmacokinetics or pharmacodynamics. SOCT of ∼600 µm thick single- and multilayered, weakly scattering phantoms with varying absorption in the range of 10–60 cm-1, equivalent to blood absorption in capillaries, is presented. SOCT measurements are compared with those using a spectrometer in transmission mode. For Indocyanine Green (ICG), a dynamic absorption measurement is demonstrated.
- Published
- 2009
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28. Full-field time-encoded frequency-domain optical coherence tomography
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Harald Sattmann, Boris Považay, Wolfgang Drexler, Boris Hermann, Angelika Unterhuber, and Holger Arthaber
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CMOS sensor ,Materials science ,medicine.diagnostic_test ,business.industry ,Ti:sapphire laser ,Laser ,Atomic and Molecular Physics, and Optics ,law.invention ,Wavelength ,Optics ,Optical microscope ,Optical coherence tomography ,law ,Frequency domain ,medicine ,Tomography ,business - Abstract
Ultrahigh axial resolution surface profiling as well as volumetric optical imaging based on time encoded optical coherence tomography in the frequency domain without any mechanical scanning element is presented. A frequency tuned broad bandwidth titanium sapphire laser is interfaced to an optical microscope (Axioskop 2 MAT, Carl Zeiss Meditec) that is enhanced with an interferometric imaging head. The system is equipped with a 640 x 480 pixel CMOS camera, optimized for the 800 nm wavelength tuning range for transmission and reflection measurements of a microscopic sample. Sample volume information over 1.3 x 1 x 0.2 mm(3) with ~3 mum axial and ~4 mum transverse resolution in tissue is acquired by a single wavelength scan over more than 100 nm optical bandwidth from760 to860 nm with 128-2048 equidistant optical frequency steps with an acquisition time of 1 to 50 ms per step. Topography and tomography with a signal to noise ratio of 83 dB is demonstrated on test surfaces and biological specimen respectively. This novel OCT technique promises to enable high speed, three dimensional imaging by employing high frame rate cameras and state of the art tunable lasers in a mechanically stable environment, due to lack of moving components while reducing the intensity on the sample.
- Published
- 2009
29. In vivo retinal optical coherence tomography at 1040 nm - enhanced penetration into the choroid
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Harald Sattmann, Boris Povazay, Wolfgang Drexler, Arturo Chavez-Pirson, Boris Hermann, and Angelika Unterhuber
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Retina ,Retinal pigment epithelium ,Materials science ,genetic structures ,medicine.diagnostic_test ,business.industry ,Retinal ,Macular degeneration ,medicine.disease ,eye diseases ,Atomic and Molecular Physics, and Optics ,chemistry.chemical_compound ,Optics ,medicine.anatomical_structure ,Choroidal neovascularization ,Optical coherence tomography ,chemistry ,medicine ,sense organs ,Choroid ,medicine.symptom ,business ,Preclinical imaging - Abstract
For the first time in vivo retinal imaging has been performed with a new compact, low noise Yb-based ASE source operating in the 1 microm range (NP Photonics, lambdac = 1040 nm, Deltalambda = 50 nm, Pout = 30 mW) at the dispersion minimum of water with ~7 microm axial resolution. OCT tomograms acquired at 800 nm are compared to those achieved at 1040 nm showing about 200 microm deeper penetration into the choroid below the retinal pigment epithelium. Retinal OCT at longer wavelengths significantly improves the visualization of the retinal pigment epithelium/choriocapillaris/choroids interface and superficial choroidal layers as well as reduces the scattering through turbid media and therefore might provide a better diagnosis tool for early stages of retinal pathologies such as age related macular degeneration which is accompanied by choroidal neovascularization, i.e., extensive growth of new blood vessels in the choroid and retina.
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- 2009
30. Three- and four-dimensional visualization of cell migration using optical coherence tomography
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Boris Považay, Wolfgang Drexler, Boris Hermann, Adrian J. Harwood, Angelika Unterhuber, Bernd Hofer, and Sara Rey
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Materials science ,Time Factors ,Opacity ,Surface Properties ,General Physics and Astronomy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,010309 optics ,03 medical and health sciences ,Optics ,Imaging, Three-Dimensional ,Optical coherence tomography ,0103 physical sciences ,medicine ,Animals ,General Materials Science ,Dictyostelium ,030304 developmental biology ,0303 health sciences ,Cell chemotaxis ,medicine.diagnostic_test ,business.industry ,Chemotaxis ,Sepharose ,General Engineering ,Collodion ,Cell migration ,Membranes, Artificial ,General Chemistry ,Visualization ,Imaging technique ,Cell tracking ,business ,Tomography, Optical Coherence - Abstract
Conventionally, cell chemotaxis is studied on two-dimensional (2D) transparent surfaces, due to limitations in optical and image data-collection techniques. However, surfaces that more closely mimic the natural environment of cells are often opaque. Optical coherence tomography (OCT) is a noninvasive label-free imaging technique, which offers the potential to visualize moving cells on opaque surfaces and in three dimensions (3D). Here, we demonstrate that OCT is an effective means of time-lapse videomicroscopy of Dictyostelium cells undergoing 3D (2D+time) cell migration on nitrocellulose substrates and 4D (3D+time) chemotaxis within low-density agarose gels. The generated image sequences are compatible with current computer-based image-analysis software for quantification of cell motility. This demonstrates the utility of OCT for cell tracking and analysis of cell chemotaxis in complex environments. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
- Published
- 2009
31. Dispersion encoded full range frequency domain OCT
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Gerald Matz, Angelika Unterhuber, Boris Hermann, Boris Povazay, Wolfgang Drexler, and Bernd Hofer
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Complex conjugate ,medicine.diagnostic_test ,Computational complexity theory ,Iterative method ,business.industry ,Spectral density ,Residual ,Optics ,Optical coherence tomography ,Frequency domain ,medicine ,business ,Mathematics ,Leakage (electronics) - Abstract
We propose an algorithm that effectively cancels complex conjugate mirror terms from single OCT A-scans by utilizing the dispersion mismatch between reference and sample arm to generate full range tomograms. This allows distinguishing between complex conjugate mirror terms and real structures and is therefore called dispersion encoded full range (DEFR). Whereas the computational complexity is higher, acquisition speed is not compromised since no additional A-scans need to be measured which makes this technique also robust against phase fluctuations. The iterative algorithm uses numeric dispersion compensation and exhibits no reduction in resolution compared to standard processing. Residual leakage of mirror terms is reduced by incorporating further knowledge such as the power spectrum of the light source. The suppression ratio of mirror signals is more than 50 dB and thus comparable to other complex FD-OCT techniques which use more than one A-scan.
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- 2009
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32. Spectroscopy in single and double layered weakly scattering phantoms with frequency domain OCT
- Author
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Wolfgang Drexler, Bernd Hofer, Boris Povazay, Boris Hermann, and Christoph Meier
- Subjects
Spectrometer ,medicine.diagnostic_test ,Chemistry ,business.industry ,Scattering ,Wavelength ,Optics ,Optical coherence tomography ,Frequency domain ,medicine ,Calibration ,Spectroscopy ,business ,Absorption (electromagnetic radiation) - Abstract
In this study, depth resolved measurements of absorption proles in the wavelength range of 800 nm with abandwidth of 140 nm are demonstrated using high speed spectroscopic frequency domain OCT (SOCT). Withproper calibration, SOCT is able to extract absolute, depth resolved absorption proles over the whole wavelengthrange at once without the need of tuning and performing measurements at single wavelengths sequentially. Inaddition, high acquisition speed in excess of 20 kHz allows to measure absorption dynamics with 50 µ s timeresolution, which might be useful for the investigation of pharmacokinetics or pharmacodynamics.SOCT of 600 µ m thick single- and multilayered, weakly scattering phantoms with varying absorption inthe range of 10 60 cm 1 , equivalent to blood absorption in capillaries, is presented. SOCT measurements arecompared with those using a spectrometer in transmission mode. For Indocyanine Green (ICG), a dynamicabsorption measurement is demonstrated.Keywords: optical coherence tomography, spectroscopy, depth-resolved, functional imaging
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- 2009
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33. Visualization of 3D cell migration using high speed ultrahigh resolution optical coherence tomography
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Angelika Unterhuber, Adrian J. Harwood, Boris Povazay, Sara Rey, Bernd Hofer, Wolfgang Drexler, and Boris Hermann
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Materials science ,Microscope ,genetic structures ,medicine.diagnostic_test ,Cell morphogenesis ,business.industry ,Resolution (electron density) ,eye diseases ,Visualization ,law.invention ,Optics ,Interference (communication) ,Optical coherence tomography ,law ,Frequency domain ,Microscopy ,medicine ,business - Abstract
Using high speed ultrahigh resolution optical coherence tomography (OCT) at 800nm, non-invasive 3D cellular imaging has been accomplished. Cellular resolution imaging on and within these types of substrates is not possible with conventional microscopy techniques such as interference contrast microscopy, and requires the use of fluorescent staining. It is possible to achieve data acquisition rates of 20,000 samples per second with OCT which, in combination with its high axial and transverse resolution (>2-3μm), allows it to be used as a non-invasive technique to analyze cell migration in 3D with time. Comparatively high penetration depth also makes OCT a uniquely suited imaging technique for visualization of cells within a 3D construct. In this paper it is demonstrated that it is possible to resolve ~10μm Dictyostelium discoideum cells, a well established and useful model for investigation of cell motility and chemotaxis, in 3D and follow them in time lapse using an 800nm ultrahigh resolution high speed frequency domain based OCT microscope. Ultimately, these visualization techniques could enable monitoring of cell behavior in regenerative medicine, for example tracking of individual cells within a cell scaffold.
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- 2009
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34. Wide field visualization of retinal and choroidal microstructure in vivo using frequency domain OCT at 1060 nm with up to 47000 lines/s
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F. Bounaparte, Rachel Valerie North, Marieh Esmaeelpour, Bernd Hofer, Nick Sheen, Wolfgang Drexler, Boris Povazay, and Boris Hermann
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Retina ,Materials science ,genetic structures ,medicine.diagnostic_test ,Pixel ,Spectrometer ,business.industry ,Retinal ,Frame rate ,eye diseases ,chemistry.chemical_compound ,Optics ,medicine.anatomical_structure ,Optical coherence tomography ,chemistry ,Frequency domain ,medicine ,sense organs ,Choroid ,business - Abstract
We present in vivo frequency domain optical coherence tomography of the human retina and choroid in the 1060 nm water transmission window with 72 nm optical bandwidth (
- Published
- 2009
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35. Techniques for extraction of depth-resolved in vivo human retinal intrinsic optical signals with optical coherence tomography
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Boris Považay, Wolfgang Drexler, Boris Hermann, Alison M. Binns, Bernd Hofer, Thomas Hengist Margrain, and Alexandre R. Tumlinson
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Materials science ,genetic structures ,Backscatter ,Dark Adaptation ,Signal ,Retina ,chemistry.chemical_compound ,Optics ,Optical coherence tomography ,medicine ,Coherence (signal processing) ,Humans ,Segmentation ,Retinal pigment epithelium ,medicine.diagnostic_test ,business.industry ,Retinal ,General Medicine ,Ophthalmology ,medicine.anatomical_structure ,chemistry ,sense organs ,Tomography ,business ,Photic Stimulation ,Tomography, Optical Coherence - Abstract
Purpose To demonstrate acquisition and analysis methods for depth-resolved observation of slow retinal physiology induced changes in infrared backscatter in vivo. Methods A dark-adapted human was briefly subjected to a localized photobleach. For 20 min before and 30 min after the stimulus, volumetric optical coherence tomograms were collected partially overlapping the bleached region. Tomograms were segmented into retinal layers by a newly described algorithm exploiting information in adjacent B-scans. En face fundus images extracted from major intraretinal layers were laterally registered manually. Time series summarizing the observed backscatter in selected layers for the bleached and unbleached areas are shown with a variety of corrections and normalizations applied: tomograms were corrected for inherent sensitivity roll-off, and the ratio between other layers and an assumed unchanging layer (retinal pigment epithelium), as well as the ratio of the stimulated area to the unstimulated area, were calculated. Results Adjacent B-scan information allows a simpler segmentation algorithm to be used. Sensitivity roll-off correction reduces signal variability due to eye motion. After normalizations, the signal correlated with the stimulus appears strongest at the photoreceptor inner-outer segment junction. Conclusions Demonstrated methods manage data complexity and reduce uncorrelated signal variability. This single trial warrants further investigation of intrinsic optical signals to observe slow physiologic responses.
- Published
- 2008
36. Revealing fine microstructural morphology in the living human retina using Optical Coherence Tomography with pancorrection
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Bernd Hofer, C. Torti, Boris Hermann, Boris Považay, Wolfgang Drexler, and Angelika Unterhuber
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Retina ,genetic structures ,medicine.diagnostic_test ,business.industry ,Retinal ,Biology ,eye diseases ,Deformable mirror ,chemistry.chemical_compound ,medicine.anatomical_structure ,Optics ,Optical coherence tomography ,chemistry ,Chromatic aberration ,Medical imaging ,medicine ,sense organs ,Adaptive optics ,business ,Biomedical engineering ,Optical aberration - Abstract
Biomedical Imaging Group, School of Optometry & Vision Sciences,Cardiff University, Wales, UKAbstract. Ultra-high speed optical coherence tomography employing an ultra-broadband lightsource has been combined with adaptive optics utilizing a single high stroke deformable mirrorandchromaticaberrationcompensation. Thereductionofmotionartefacts,geometricandchro-matic aberrations (pancorrection) permits to achieve an isotropic resolution of 2 3 µminthehuman eye. The performance of this non-invasive imaging modality enables to resolve cellularstructuresincludingconephotoreceptors, nervebrebundlesandcollagenousplatesofthelam-ina cribrosa, and retinal pigment epithelial (RPE) cells in the human retina in vivo with superiordetail. Alterations of cellular morphology due to cone degeneration in a colour-blind subjectare investigated in ultra-high resolution with selective depth sectioning for the rst time.Keywords: adaptive optics, achromatizer, pancorrection, photoreceptors, retinal pigment ep-ithelial (RPE) cells, lamina cribrosa, colour-blind, retinal pathology
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- 2008
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37. Retinal intrinsic optical signal and optical coherence tomography
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Bernd Hofer, Thomas Hengist Margrain, Boris Považay, Wolfgang Drexler, Alexandre R. Tumlinson, and Boris Hermann
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Physics ,Retina ,genetic structures ,Ccd camera ,Backscatter ,medicine.diagnostic_test ,business.industry ,Retinal ,Neural tissues ,Signal ,eye diseases ,Communication noise ,chemistry.chemical_compound ,Optics ,medicine.anatomical_structure ,chemistry ,Optical coherence tomography ,medicine ,sense organs ,business - Abstract
The amount of light backscattered from neural tissues changes as a function of activation and is the basis of intrinsic optical signal (IOS). Typically IOS is observed by looking at darkfield scatter with a CCD camera. The retina is a calculating portion of the central nervous grey matter with an optical quality window, and is likewise easily stimulated optically. Therefore the retina makes a natural model for observing neural interactions with optical tools. Optical coherence tomography (OCT) is an imaging modality that provides depth resolved maps of the amount of light backscattered from tissue that has wide clinical use for observing structural defects associated with ophthalmic disease. It is therefore also natural to use OCT as means to observe intrinsic optical signal in the retina. Indeed, OCT has recently been used to observe an increase in backscatter at the level of the outer photoreceptor segment after bleaching light stimulation in an excised rabbit retina. We are currently attempting to translate this result towards a diagnostic technique for photoreceptor dysfunction in human patients. Currently patient motion and physiological noise present barriers that must be overcome with increases in technological and experimental sophistication. This proceeding reviews current understanding of retinal intrinsic optical signal and discusses its measurement challenge.
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- 2008
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38. Ultrahigh resolution optical coherence tomography and pancorrection for cellular imaging of the living human retina
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Peter K. Ahnelt, Angelika Unterhuber, Boris Hermann, Bernd Hofer, Boris Považay, Enrique J. Fernández, Wolfgang Drexler, and Harald Sattmann
- Subjects
genetic structures ,Sensitivity and Specificity ,Deformable mirror ,Retina ,law.invention ,Optics ,Optical coherence tomography ,law ,Foveal ,Image Interpretation, Computer-Assisted ,medicine ,Humans ,Chromatic scale ,Adaptive optics ,Physics ,Tomographic reconstruction ,medicine.diagnostic_test ,business.industry ,Lasers ,Laser ,Image Enhancement ,eye diseases ,Atomic and Molecular Physics, and Optics ,sense organs ,Monochromatic color ,business ,Tomography, Optical Coherence ,Retinoscopy - Abstract
Cellular in vivo visualization of the three dimensional architecture of individual human foveal cone photoreceptors is demonstrated by combining ultrahigh resolution optical coherence tomography and a novel adaptive optics modality. Isotropic resolution in the order of 2-3 microm, estimated from comparison with histology, is accomplished by employing an ultrabroad bandwidth Titanium:sapphire laser with 140 nm bandwidth and previous correction of chromatic and monochromatic ocular aberrations. The latter, referred to as pancorrection, is enabled by the simultaneous use of a specially designed lens and an electromagnetically driven deformable mirror with unprecedented stroke for correcting chromatic and monochromatic aberrations, respectively. The increase in imaging resolution allows for resolving structural details of distal elements of individual foveal cones: inner segment zones--myoids and ellipsoids--are differentiated from outer segments protruding into pigment epithelial processes in the retina. The presented technique has the potential to unveil photoreceptor development and pathogenesis as well as improved therapy monitoring of numerous retinal diseases.
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- 2008
39. Quantification of retinal transneuronal degeneration in human glaucoma: a novel multiphoton-DAPI approach
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Nigel John Garrahan, M. Rosario Hernandez, Yuan Lei, David L. Becker, Michael E. Boulton, Boris Hermann, and James Edwards Morgan
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Retinal Ganglion Cells ,medicine.medical_specialty ,Indoles ,genetic structures ,Glaucoma ,Cell Count ,Biology ,Transneuronal degeneration ,Retinal ganglion ,chemistry.chemical_compound ,Ophthalmology ,Optic Nerve Diseases ,medicine ,Humans ,DAPI ,Outer nuclear layer ,Aged ,Fluorescent Dyes ,Aged, 80 and over ,Cell Nucleus ,Neurons ,Retina ,Microscopy, Confocal ,Retinal ,Middle Aged ,medicine.disease ,eye diseases ,medicine.anatomical_structure ,chemistry ,Retinal ganglion cell ,Nerve Degeneration ,RE ,sense organs ,Algorithms ,Glaucoma, Open-Angle - Abstract
purpose. Glaucoma is presumed to result in the selective loss of retinal ganglion cells. In many neural systems, this loss would initiate a cascade of transneuronal degeneration. The quantification of changes in neuronal populations in the middle layers of the retina can be difficult with conventional histologic techniques. A method was developed based on multiphoton imaging of 4′,6′-diamino-2-phenylindole (DAPI)–stained tissue to quantify neuron loss in postmortem human glaucomatous retinas. methods. Retinas from normal and glaucomatous eyes fixed in 4% paraformaldehyde were incubated at 4°C overnight in DAPI solution. DAPI-labeled neurons at different levels of the retina were imaged by multiphoton confocal microscopy. Algorithms were developed for the automated identification of neurons in the retinal ganglion cell layer (RGCL), inner nucleus layer (INL), and outer nuclear layer (ONL). results. In glaucomatous retinas, the mean density of RGCs within 4 mm eccentricity was reduced by approximately 45%, with the greatest RGC loss occurring in a region that corresponds to the central 6° to 14° of vision. Significant neuron loss in the INL and ONL was also seen at 2 to 4 mm and 2 to 3 mm eccentricities, respectively. The ratios of neuron densities in the INL and ONL relative to the RGCL (INL/RGC and ONL/RGC, respectively) were found to increase significantly at 3 to 4 mm eccentricity. conclusions. The data confirm that the greatest neuronal loss occurs in the RGCL in human glaucoma. Neuronal loss was also observed in the outer retinal layers (INL and ONL) that correlated spatially with changes in the RGCL. Further work is necessary to confirm whether these changes arise from transneuronal degeneration.
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- 2008
40. High Speed, Spectrometer Based Optical Coherence Tomography at 1050 nm for Isotropic 3D OCT Imaging and Visualization of Retinal and Choroidal Vasculature
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Bernd Hofer, Vedran Kajić, Boris Považay, Wolfgang Drexler, and Boris Hermann
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Materials science ,genetic structures ,Spectrometer ,medicine.diagnostic_test ,Image quality ,business.industry ,Isotropy ,Image registration ,Retinal ,eye diseases ,Visualization ,chemistry.chemical_compound ,Optics ,Three dimensional imaging ,chemistry ,Optical coherence tomography ,medicine ,sense organs ,business - Abstract
Spectrometer based optical coherence tomography at 1050nm with >70nm of spectral bandwidth, acquiring 48k depth scans per second for deeper penetration and isotropic visualisation of the full three dimensional choroidal vasculature is demonstrated in vivo.
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- 2008
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41. Towards in vivo imaging of photoreceptor morphology and function
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Boris Považay, Bernd Hofer, Wolfgang Drexler, E.J. Fernandez, Peter K. Ahnelt, Alison M. Binns, Angelika Unterhuber, Thomas Hengist Margrain, C. Torti, and Boris Hermann
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Retina ,genetic structures ,medicine.diagnostic_test ,business.industry ,Biology ,eye diseases ,medicine.anatomical_structure ,Optics ,Optical coherence tomography ,Lens (anatomy) ,medicine ,White light ,Retinal function ,sense organs ,Adaptive optics ,business ,Preclinical imaging ,Function (biology) ,Biomedical engineering - Abstract
The integration of adaptive optics and an achromatizing lens into an ultra-high resolution OCT system enables three-dimensional imaging of photoreceptor morphology. Optophysiology might lead to the extraction of depth-resolved information about retinal function.
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- 2008
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42. ELECTROMAGNETIC DEFORMABLE MIRROR: EXPERIMENTAL ASSESSMENT AND FIRST OPHTHALMIC APPLICATIONS – Poster Paper
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Laurent Vabre, N. Chateau, Angelika Unterhuber, Wolfgang Drexler, B. Považay, Boris Hermann, Fabrice Harms, E. J. Fernandez, and J. Charton
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business.industry ,Computer science ,Computer graphics (images) ,Computer vision ,Artificial intelligence ,business ,Deformable mirror - Published
- 2008
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43. Submicrometer axial resolution optical coherence tomography
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Harald Sattmann, Kostadinka Bizheva, E. Scherzer, M. Vetterlein, Alexander Apolonski, William J. Wadsworth, Boris Povazay, Wolfgang Drexler, Jonathan Knight, Boris Hermann, P. St. J. Russell, Angelika Unterhuber, and Adolf Friedrich Fercher
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Materials science ,genetic structures ,medicine.diagnostic_test ,business.industry ,Resolution (electron density) ,Laser ,Atomic and Molecular Physics, and Optics ,law.invention ,Optics ,Optical coherence tomography ,law ,medicine ,Optoelectronics ,sense organs ,Emission spectrum ,Optical tomography ,business ,Image resolution ,Photonic crystal ,Photonic-crystal fiber - Abstract
Optical coherence tomography (OCT) with unprecedented submicrometer axial resolution achieved by use of a photonic crystal fiber in combination with a compact sub-10-fs Ti:sapphire laser (Femtolasers Produktions) is demonstrated for what the authors believe is the first time. The emission spectrum ranges from 550 to 950 nm (lambda(c)=725 nm , P(out)=27 mW) , resulting in a free-space axial OCT resolution of ~0.75 mum , corresponding to ~0.5 mum in biological tissue. Submicrometer-resolution OCT is demonstrated in vitro on human colorectal adenocarcinoma cells HT-29. This novel light source has great potential for development of spectroscopic OCT because its spectrum covers the absorption bands of several biological chromophores.
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- 2007
44. Optical coherence tomography of the choroid at 1050nm
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Boris Povazay, Bernd Hofer, Harald Sattmann, Boris Hermann, Wolfgang Drexler, and Angelika Unterhuber
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Retina ,Retinal pigment epithelium ,genetic structures ,medicine.diagnostic_test ,business.industry ,Scattering ,Retinal ,eye diseases ,Ophthalmology ,chemistry.chemical_compound ,Optics ,Spectral sensitivity ,medicine.anatomical_structure ,chemistry ,Optical coherence tomography ,medicine ,sense organs ,Choroid ,Tomography ,business ,Biomedical engineering - Abstract
Purpose: Optical coherence tomography is a well established imaging modality for the retina at 800 nm, but is limited in its capability to visualize through scattering tissue, like through cataract or into the choroid. Methods: Utilizing the lower scattering at longer wavelengths (1050 nm) high speed (>17 kHz), high axial resolution (~7 μm) optical coherence tomography (OCT) demonstrates its abil-ity to exploit the three dimensional anatomic microstructure of the choroid. Volumetric images, obtained with spectrometer based frequency domain OCT system are presented and compared with their counterparts acquired at the commonly used 800 nm range. Results: Tomograms of normals and patients with pathologic morphological changes of the retinal structure as well as with cataract depict improved signal strength and image contrast at the longer wavelength. The deeper penetration allows reconstruction of the choroidal vascular structure despite strong scattering of superficial tissues at the retinal pigment epithelium, the choriocapillaris also including pathologic retinal thickening. Visualisation of modifications in the choroidal vascular structure associated with wet age related macu-lar degeneration or diabetic retinopathy indicate the diagnostic potential of this technique. Furthermore, being well outside the spectral sensitivity of the eye the wavelength band at 1050 nm also allows for depth resolved profiling of reflectivity changes to directly moni-tor light stimulus related retinal activity, without interference due to the sampling OCT beam. Conclusions: Imaging at 1050 nm enables not only to track morphological but also functional changes of the retina.
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- 2007
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45. Minimum distance mapping using three-dimensional optical coherence tomography for glaucoma diagnosis
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Carl Glittenberg, Bernd Hofer, Angelika Unterhuber, Susanne Binder, Boris Hermann, James Edwards Morgan, Wolfgang Drexler, and Boris Povazay
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Models, Anatomic ,Materials science ,genetic structures ,Optic Disk ,Biomedical Engineering ,Nerve fiber layer ,Glaucoma ,Pilot Projects ,Models, Biological ,Sensitivity and Specificity ,Pattern Recognition, Automated ,Biomaterials ,chemistry.chemical_compound ,Optics ,Imaging, Three-Dimensional ,Optical coherence tomography ,Image Interpretation, Computer-Assisted ,Optic Nerve Diseases ,medicine ,Humans ,Computer Simulation ,Retina ,medicine.diagnostic_test ,business.industry ,Minimum distance ,Reproducibility of Results ,Retinal ,medicine.disease ,Image Enhancement ,eye diseases ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,medicine.anatomical_structure ,chemistry ,Optic nerve ,sense organs ,Tomography ,business ,Algorithms ,Tomography, Optical Coherence ,Biomedical engineering ,Retinoscopy - Abstract
Objective imaging of the optic nerve structure has become central to the management of patients with glaucoma. There is an urgent need in diagnosis and staging for reliable objective precursors and markers. Three-dimensional ultrahigh-resolution frequency domain optical coherence tomography (3D UHR OCT) holds particular promise in this respect since it enables volumetric assessment of intraretinal layers including tomographic data for the retinal nerve fiber layer (RNFL) and optic nerve head. The integrated analysis of this information and the resolution advantage has enabled the development of more informative indices of axonal damage in glaucoma compared with measurements of RNFL thickness and cup-to-disc ratio provided by commercial OCT devices. The potential for UHR OCT in enabling the combined analysis of tomographic and volumetric data on retinal structure is explored. A novel parameter was developed; the three-dimensional minimal distance as the optical correlate of true retinal nerve fiber layer thickness around the optic nerve head region. For the purposes of this pilot study, we present data from a normal subject and from two patients with characteristic optic nerve and retinal nerve fiber layer changes secondary to glaucoma.
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- 2007
46. Serial endoscopy in azoxymethane treated mice using ultra-high-resolution optical coherence tomography
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Lida P. Hariri, Ziping Qiu, Alexandre R. Tumlinson, David G. Besselsen, Eugene W. Gerner, Natalia Ignatenko, Boris Považay, Boris Hermann, Harald Sattmann, James McNally, Angelika Unterhuber, Wolfgang Drexler, and Jennifer K. Barton
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- 2007
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47. Signal post processing in frequency domain OCT and OCM using a filter bank approach
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Angelika Unterhuber, Boris Považay, Boris Hermann, Wolfgang Drexler, Franz Hlawatsch, Bernd Hofer, and Gerald Matz
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Physics ,Spectrometer ,Finite impulse response ,business.industry ,Fast Fourier transform ,Filter bank ,Signal ,symbols.namesake ,Optics ,Fourier transform ,Aliasing ,Frequency domain ,symbols ,business ,Algorithm - Abstract
Current signal post processing in spectrally encoded frequency domain (FD) optical coherence microscopy (OCM) and optical coherence tomography (OCT) uses Fourier transforms in combination with non-uniform resampling strategies to map the k-space data acquired by the spectrometer to spatial domain signals which are necessary for tomogram generation. We propose to use a filter bank (FB) framework for the remapping process. With our new approach, the spectrometer is modeled as a critically sampled analysis FB, whose outputs are quantized subband signals that constitute the k-space spectroscopic data. The optimal procedure to map this data to the spatial domain is via a suitably designed synthesis FB which has low complexity. FB theory additionally states that 1) it is possible to find a synthesis FB such that the overall system has the perfect reconstruction (PR) property; 2) any processing on critically sampled subband signals (as done in current schemes) results in aliasing artifacts. These perspectives are evaluated both theoretically and experimentally. We determine the analysis FB corresponding to our FD-OCM system by using a tunable laser and show that for our grating-based spectrometer - employing a CCD-line camera - the non-uniform resampling together with FFT indeed causes aliasing terms and depth dependent signal attenuation. Furthermore, we compute a finite impulse response based synthesis FB and assess the desired PR property by means of layered samples. The resulting images exhibit higher resolution and improved SNR compared to the common FFT-based approach. The potential of the proposed FB approach opens a new perspective also for other spectroscopic applications.
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- 2007
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48. In vivo ultrahigh-resolution optical coherence tomography of mouse colon with an achromatized endoscope
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Boris Považay, Lida P. Hariri, Wolfgang Drexler, Boris Hermann, Alexandre R. Tumlinson, Angelika Unterhuber, Jennifer K. Barton, Harald Sattmann, and James B. McNally
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Materials science ,genetic structures ,Colon ,Biomedical Engineering ,Sensitivity and Specificity ,law.invention ,Biomaterials ,Mice ,Optics ,Optical coherence tomography ,law ,medicine ,Animals ,Time domain ,medicine.diagnostic_test ,Colonoscopes ,business.industry ,Color correction ,Reproducibility of Results ,Equipment Design ,Laser ,Image Enhancement ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Equipment Failure Analysis ,Wavelength ,Achromatic lens ,sense organs ,business ,Preclinical imaging ,Tomography, Optical Coherence ,Coherence (physics) - Abstract
Endoscopic ultrahigh-resolution optical coherence tomog- raphy OCT enables collection of minimally invasive cross-sectional images in vivo, which may be used to facilitate rapid development of reliable mouse models of colon disease as well as assess chemopre- ventive and therapeutic agents. The small physical scale of mouse colon makes light penetration less problematic than in other tissues and high resolution acutely necessary. In our 2-mm diameter endo- scopic time domain OCT system, isotropic ultrahigh-resolution is sup- ported by a center wavelength of 800 nm and full-width-at-half- maximum bandwidth of 150 nm mode-locked titanium:sapphire laser combined with 1:1 conjugate imaging of a small core fiber. A pair of KZFSN5/SFPL53 doublets provides excellent color correction to support wide bandwidth throughout the imaging depth. A slight deviation from normal beam exit angle suppresses collection of the strong back reflection at the exit window surface. Our system achieves axial resolution of 3.2 m in air and 4.4-m lateral spot diameter with 101-dB sensitivity. Microscopic features too small to see in mouse tissue with conventional resolution systems, including colonic crypts, are clearly resolved. Resolution near the cellular level is potentially capable of identifying abnormal crypt formation and dysplastic cellular organization. © 2006 Society of Photo-Optical Instrumentation
- Published
- 2007
49. Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging
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Angelika Unterhuber, Tschackad Kamali, Jonathan M. Levitte, Yaron Silberberg, René M. Werkmeister, Boris Považay, Wolfgang Drexler, Sunil Kumar, Boris Hermann, and Ori Katz
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Materials science ,Microscope ,medicine.diagnostic_test ,business.industry ,Nonlinear optics ,Second-harmonic generation ,Laser ,Atomic and Molecular Physics, and Optics ,law.invention ,Laser linewidth ,symbols.namesake ,Optics ,Optical coherence tomography ,law ,Femtosecond ,medicine ,symbols ,business ,Raman scattering - Abstract
Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly alignment-free multimodal nonlinear optical microscope that is based on a single wide-band Ti:Sapphire femtosecond pulse laser source. Successful imaging tests have been realized on two exemplary biological samples, a canine femur bone and collagen fibrils harvested from a rat tail. Since the ultra-broad band-width femtosecond laser is a suitable source for performing high-resolution optical coherence tomography, a wide-field optical coherence tomography arm can be easily incorporated into the presented multimodal microscope making it a versatile optical imaging tool for noninvasive label-free bioimaging.
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- 2015
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50. Optophysiology: depth-resolved probing of retinal physiology with functional ultrahigh-resolution optical coherence tomography
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Sergei Popov, Peter K. Ahnelt, Angelika Unterhuber, P. Qiu, Kostadinka Bizheva, Boris Hermann, E.M. Anger, Herbert A. Reitsamer, Harald Sattmann, R. Pflug, James Taylor, Boris Považay, and Wolfgang Drexler
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genetic structures ,Stimulation ,Neurotransmission ,Biology ,Stimulus (physiology) ,In Vitro Techniques ,Retina ,chemistry.chemical_compound ,Optical coherence tomography ,medicine ,Animals ,Photoreceptor Cells ,Image resolution ,Multidisciplinary ,medicine.diagnostic_test ,Retinal ,Anatomy ,Biological Sciences ,eye diseases ,medicine.anatomical_structure ,chemistry ,Ultrahigh resolution ,Biophysics ,sense organs ,Rabbits ,Tomography, Optical Coherence - Abstract
Noncontact, depth-resolved, optical probing of retinal response to visual stimulation with a
- Published
- 2006
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