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T. Nagaoka, A. Nakamura, K. Aizawa, M. Kanazawa, T. Kezuka, M. Miura, M. Usui, S. Ohtsubo, T. Sota; Near-Infrared Hyperspectral Images of Human Ocular Fundus and Their Processing With Decorrelation Stretch. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2752.
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© ARVO (1962-2015); The Authors (2016-present)
Indocyanine green fluorescence angiography (IA) makes it possible to image choroidal blood vessels. Despite the widespread acceptance of IA, its application has been restricted due to the possibility of severe complication and the discomfort of patients. The purpose of this presentation is to evaluate the potentiality of other technique to image choroidal blood vessels without contrast media.
We customized commercialized conventional fundus camera to develop near-infrared, 720 nm < < 920 nm, hyperspectral fundus imaging apparatus. The hyperspectral image means an image each pixel of which has spectral information. As image processing, we applied decorrelation stretch to three single wavelength images with different central wavelength and the same bandwidth of 20 nm in order to separate choroidal blood vessels from other tissues.
Choroidal blood vessels were seen as bright images in single wavelength images whose central wavelength is shorter than 840 nm, while retinal blood vessels were seen as dark images in all single wavelength images under study. The decorrelation stretch could emphasize the choroidal blood vessels in the 2nd principal component image and the retinal ones in the 1st principal component image, see Fig.1.
Combination of hyperspectral images with decorrelation stretch made it possible to separate the blood vessels in the choroid from the retina. Application of the proposed method to patients will be given in the presentation.
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