Imaging Spectrometry in Ophthalmology – Principle and Applications in Microcirculation and in Investigation of Pigments

Schweitzer, Dietrich; Hammer, Martin; Scibor, M.

doi:10.1159/000267955

Cited by 32 publications

(23 citation statements)

References 16 publications

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“…[35][36][37][38] One of the imaging variants of fundus reflectometry uses a TV-based imaging fundus reflectometer with sequential, narrow-bandwidth light excitation over the visible wavelength range and digitized fundus images. 39 Another powerful variant uses a scanning laser ophthalmoscope, 40,41 employing raster-scanning of the fundus with discrete laser excitation wavelengths to produce highly detailed information about the spatial distribution [42][43][44][45][46] of MP (and photopigments). In autofluorescence spectroscopy, lipofuscin in the retinal pigment epithelium is excited with light within and outside the wavelength range of macular pigment absorption.…”

Section: Macular Pigments and Existing Measuring Methodsmentioning

confidence: 99%

Resonance Raman detection of carotenoid antioxidants in living human tissue

et al. 2005

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Increasing evidence points to the beneficial effects of carotenoid antioxidants in the human body. Several studies, for example, support the protective role of lutein and zeaxanthin in the prevention of age-related eye diseases. If present in high concentrations in the macular region of the retina, lutein and zeaxanthin provide pigmentation in this most light sensitive retinal spot, and as a result of light filtering and/or antioxidant action, delay the onset of macular degeneration with increasing age. Other carotenoids, such as lycopene and beta-carotene, play an important role as well in the protection of skin from UV and short-wavelength visible radiation. Lutein and lycopene may also have protective function for cardiovascular health, and lycopene may play a role in the prevention of prostate cancer. Motivated by the growing importance of carotenoids in health and disease, and recognizing the lack of any accepted noninvasive technology for the detection of carotenoids in living human tissue, we explore resonance Raman spectroscopy as a novel approach for noninvasive, laser optical carotenoid detection. We review the main results achieved recently with the Raman detection approach. Initially we applied the method to the detection of macular carotenoid pigments, and more recently to the detection of carotenoids in human skin and mucosal tissues. Using skin carotenoid Raman instruments, we measure the carotenoid response from the stratum corneum layer of the palm of the hand for a population of 1375 subjects and develope a portable skin Raman scanner for field studies. These experiments reveal that carotenoids are a good indicator of antioxidant status. They show that people with high oxidative stress, like smokers, and subjects with high sunlight exposure, in general, have reduced skin carotenoid levels, independent of their dietary carotenoid consumption. We find the Raman technique to be precise, specific, sensitive, and well suitable for clinical as well as field studies. The noninvasive laser technique may become a useful method for the correlation between tissue carotenoid levels and risk for malignancies or other degenerative diseases associated with oxidative stress.

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Section: Macular Pigments and Existing Measuring Methodsmentioning

confidence: 99%

Resonance Raman detection of carotenoid antioxidants in living human tissue

et al. 2005

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“…Grundgerät ist eine Funduskamera, in deren Beleuchtungsstrahlengang eine schlitzförmige Blende einschwenkbar ist [8,22] …”

Section: Ansätze Zur Objektiven Erfassung Von Altersbedingten Verändeunclassified

“…Dabei sind E i (l) aus der Literatur entnommene Extinktionsspektren der Fundussubstanzen [28] und PA[i] Wichtungsparameter, die bei der Spektrenanpassung optimiert werden. Insbesondere ist das Produkt PA[1]·E Xanth (l) die optische Dichte des in der Makula konzentrierten Pigments Xanthophyll.Werden die Reflexionsspektren längs des Beleuchtungsspaltes durch eine Modellfunktion angepasst, in der die Lichtanteile betrachtet werden, die beispielsweise am Pigmentepithel und an der Sklera reflektiert werden[13], so ist ortsabhängig neben der optischen Dichte von Xanthophyll auch die optische Dichte des Melanins und des Aderhautblutes zu berechnen[22]. Eine weitere Trennung zwischen den Melaninanteilen im retinalen Pigmentepithel und in der Aderhaut wird durch Anwendung der Adding-Doubling-Methode erreicht[7].…”

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Fundusspektrometrie bei altersbezogener Makulopathie

Schweitzer¹,

Beuermann²,

Hammer³

et al. 2005

Klin Monatsbl Augenheilkd

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“…[5][6][7][8][9][10] A multispectral image set I͑x , y , ͒, referred to as a spectral cube or a lambda stack, contains spatial ͑pixel͒ information along two dimensions ͑x , y͒ and spectral information along the third dimension . With spectral data available at each image point x = ͑x , y͒ it is possible to derive quantitative maps of diagnostically important physiological parameters such as, for example, blood oxygenation, melanin pigmentation, and density of macular pigment.…”

Section: Introductionmentioning

confidence: 99%

Multispectral imaging of the ocular fundus using light emitting diode illumination

Everdell

Styles

Calcagni

et al. 2010

Review of Scientific Instruments

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We present an imaging system based on light emitting diode (LED) illumination that produces multispectral optical images of the human ocular fundus. It uses a conventional fundus camera equipped with a high power LED light source and a highly sensitive electron-multiplying charge coupled device camera. It is able to take pictures at a series of wavelengths in rapid succession at short exposure times, thereby eliminating the image shift introduced by natural eye movements (saccades). In contrast with snapshot systems the images retain full spatial resolution. The system is not suitable for applications where the full spectral resolution is required as it uses discrete wavebands for illumination. This is not a problem in retinal imaging where the use of selected wavelengths is common. The modular nature of the light source allows new wavelengths to be introduced easily and at low cost. The use of wavelength-specific LEDs as a source is preferable to white light illumination and subsequent filtering of the remitted light as it minimizes the total light exposure of the subject. The system is controlled via a graphical user interface that enables flexible control of intensity, duration, and sequencing of sources in synchrony with the camera. Our initial experiments indicate that the system can acquire multispectral image sequences of the human retina at exposure times of 0.05 s in the range of 500-620 nm with mean signal to noise ratio of 17 dB (min 11, std 4.5), making it suitable for quantitative analysis with application to the diagnosis and screening of eye diseases such as diabetic retinopathy and age-related macular degeneration.

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Imaging Spectrometry in Ophthalmology – Principle and Applications in Microcirculation and in Investigation of Pigments

Cited by 32 publications

References 16 publications

Resonance Raman detection of carotenoid antioxidants in living human tissue

Resonance Raman detection of carotenoid antioxidants in living human tissue

Fundusspektrometrie bei altersbezogener Makulopathie

Multispectral imaging of the ocular fundus using light emitting diode illumination

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