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Autofluorescence Imaging (autofluorescence + imaging)

Distribution by Scientific Domains
Medical Sciences87%

Selected Abstracts

Clinical use and research applications of Heidelberg retinal angiography and spectral-domain optical coherence tomography , a review

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 1 2009
Andrea Hassenstein MD
Abstract Fluorescein angiography (FA) was discovered by Nowotny and Alvis in the 1960s of the 20th century and has evolved to become the ,Gold standard' for macular diagnostics. Scanning laser imaging technology achieved enhancement of contrast and resolution. The combined Heidelberg retina angiograph (HRA2) adds novel innovative features to established fundus cameras. The principle of confocal scanning laser imaging provides a high resolution of retinal and choroidal vasculature with low light exposure providing comfort and safety for the patient. Enhanced contrast, details and image sharpness image are generated using confocality. For the visualization of the choroid an indocyanine green angiography (ICGA) is the most suitable application. The main indications for ICGA are age-related macular degeneration, choroidal polypoidal vasculopathy and choroidal haemangiomas. Simultaneous digital FA and ICGA images with three-dimensional resolution offer improved diagnosis of retinal and choroidal pathologies. High-speed ICGA dynamic imaging can identify feeder vessels and retinal choroidal anastomoses, ensuring safer treatment of choroidal neovascularization. Autofluorescence imaging and fundus reflectance imaging with blue and infrared light offer new follow-up parameters for retinal diseases. Finally, the real-time optical coherence tomography provides a new level of accuracy for assessment of the angiographic and morphological correlation. The combination of various macular diagnostic tools, such as infrared, blue reflectance, fundus autofluorescence, FA, ICGA and also spectral domain optical coherence tomography, lead to a better understanding and improved knowledge of macular diseases. [source]

Short-term plasticity visualized with flavoprotein autofluorescence in the somatosensory cortex of anaesthetized rats

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2004
Hiroatsu Murakami
Abstract In the present study, short-term plasticity of somatosensory neural responses was investigated using flavoprotein autofluorescence imaging in rats anaesthetized with urethane (1.5 g/kg, i.p.) Somatosensory neural activity was elicited by vibratory skin stimulation (50 Hz for 1 s) applied on the surface of the left plantar hindpaw. Changes in green autofluorescence (, = 500,550 nm) in blue light (, = 450,490 nm) were elicited in the right somatosensory cortex. The normalised maximal fluorescence responses (,F/F) was 2.0 ± 0.1% (n = 40). After tetanic cortical stimulation (TS), applied at a depth of 1.5,2.0 mm from the cortical surface, the responses elicited by peripheral stimulation were significantly potentiated in both peak amplitude and size of the responsive area (both P < 0.02; Wilcoxon signed rank test). This potentiation was clearly observed in the recording session started 5 min after the cessation of TS, and returned to the control level within 30 min. However, depression of the responses was observed after TS applied at a depth of 0.5 mm. TS-induced changes in supragranular field potentials in cortical slices showed a similar dependence on the depth of the stimulated sites. When TS was applied on the ipsilateral somatosensory cortex, marked potentiation of the ipsilateral responses and slight potentiation of the contralateral responses to peripheral stimulation were observed after TS, suggesting the involvement of commissural fibers in the changes in the somatosensory brain maps. The present study clearly demonstrates that functional brain imaging using flavoprotein autofluorescence is a useful technique for investigating neural plasticity in vivo. [source]

Multispectral fluorescence lifetime imaging by TCSPC

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2007
Wolfgang Becker
Abstract We present a fluorescence lifetime imaging technique with simultaneous spectral and temporal resolution. The technique is fully compatible with the commonly used multiphoton microscopes and nondescanned (direct) detection. An image of the back-aperture of the microscope lens is projected on the input of a fiber bundle. The input of the fiber bundle is circular, and the output is flattened to match the input slit of a spectrograph. The spectrum at the output of the spectrograph is projected on a 16-anode PMT module. For each detected photon, the encoding logics of the PMT module deliver a timing pulse and the number of the PMT channel in which the photon was detected. The photons are accumulated by a multidimensional time-correlated single photon counting (TCSPC) process. The recording process builds up a four-dimensional photon distribution over the times of the photons in the excitation pulse period, the wavelengths of the photons, and the coordinates of the scan area. The method delivers a near-ideal counting efficiency and is capable of resolving double-exponential decay functions. We demonstrate the performance of the technique for autofluorescence imaging of tissue. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source]

1334: Autofluorescence: new tool to follow dry eye AMD?

ACTA OPHTHALMOLOGICA, Issue 2010
MN MENKE
Purpose In the pathophysiolgy of dry (atrophic) age related macular degeneration (AMD) aging of the retinal pigment epithelium (RPE) plays a key role. Accumulation of lipofuscin granules in the RPE cells represents a common downstream pathogenetic pathway in AMD. Lipofuscin is derived from chemically modified residues of incompletely digested photoreceptor outer segment discs. Detection of lipofuscin in vivo is possible by using fundus autofluorescence (FAF) imaging. The clinical application and possible implications of autofluorescence imaging in dry AMD will be discussed. Methods When stimulated with light in the blue to green range, lipofuscin granules emit a characteristic yellow fluorescence. FAF imaging using a scanning laser ophthalmoscope allows visualization of the topographic distribution of lipofuscin over large retinal areas. Examples of FAF images will be presented to demonstrate various FAF patterns and to discuss the clinical significance of these findings. Results In areas of geographic atrophy FAF images show very low autofluorescence intensity. This is due to the loss of RPE cells including the lipofuscin granules. In the junctional zone between atrophic and normal retina, levels of increased autofluorescence intensity may occur due to excessive accumulation of lipofuscin in the RPE cells. Longitudinal observations further suggest that the extension of the total area with increased autofluorescence intensity surrounding atrophy at baseline has a strong positive correlation with atrophy progression rate over time. Conclusion FAF imaging is an important diagnostic tool to follow the progression of dry AMD and other degenerative macular diseases and should always be considered in cases were the status of the RPE is unknown. [source]

2113: AO imaging in AMD

ACTA OPHTHALMOLOGICA, Issue 2010
N MASSAMBA
Purpose Two different systems, adaptive optics scanning laser ophthalmoscope (AOSLO), and Spectral Domain Ophtalmoloscopy (SD-OCT) were used to visualize cones in the outer neurosensory retina overlying soft macular drusen and the surrounding retinal areas. Methods High resolution images were obtained with Adaptive Optics (AO) in addition to complete ophthalmic examination including BCVA on ETDRS chart, biomicroscopic examination, autofluorescence imaging, fluorescein and indocyanine angiographies (HRA2 Heidelberg ,Germany) and SD-OCT. The AO image are then compared with conventional infrared and SD-OCT. Soft macular drusen from 50 patients (age between 65 and 85) visible on the scanning laser ophthalmoscope(SLO) examination were evaluated included in the study Results The soft drusen were visible in AO images as generally round areas delimited by a peripheral low-reflectance line. The highly reflective photoreceptor inner/outer segment junction (IS/OS) can be used as a pattern of photoreceptors integrity in SD-OCT images. In areas where the IS/OS junction is absent on SD-OCT, no cones are visualized in registered AOSLO images. In the inner area of many drusen, hyper reflective spots of a size between 2 and 15 µm were sometimes isolated, sometimes grouped into tight aggregates of 2 to 40 components. Cone photoreceptors were visible in areas between drusen in most AO images, however the mosaic image sharpness was significantly less uniform in these elderly patients than previously observed in younger, healthy retinas. Conclusion This study shows the synergistic nature of these two high-resolution retinal imaging systems The microscopic characteristics of soft drusen on AO imaging suggest some analogy with the anatomopathologic characteristics. AO technology will be a powerful tool to refine their clinical classification [source]

Fundus autofluorescence imaging of macular star

ACTA OPHTHALMOLOGICA, Issue 6 2009
Ali Ayata
No abstract is available for this article. [source]

Fundus autofluorescence imaging of choroidal tumors

ACTA OPHTHALMOLOGICA, Issue 2008
E PILOTTO
Purpose To investigate the different pattern of fundus autofluorescence imaging of choroidal tumors generated with short-wavelength and near-infrared Methods Thirty-one eyes of 31 consecutive patients affected by choroidal tumor performed standard fundus autofluorescence with short-wavelength (SW FAF) and fundus autofluorescence with near-infrared (NIR FAF). Fundus photography, A and B scan ultrasound and OCT were performed. Autofluorescence features of choroidal tumor and overlying retinal pigment epithelium (RPE) were correlated with clinical features. Results Twelve of 31 choroidal tumors were choroidal melanoma, 8 choroidal nevus, 5 circumscribed choroidal hemangioma and one was choroidal granuloma. Different pattern of SW FAF and NIR FAF were detected related to the presence of pigment, drusen, RPE atrophy and hyperplasia, RPE detachment and subretinal fluid over or around the lesion. Conclusion Standard autofluorescence (SW FAF) and NIR FAF provide different information on intrinsic autofluorescence of choroidal tumor and on the related RPE and retinal changes [source]