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Shuliang Jiao, Carmen A. Puliafito, Hao F. Zhang; Simultaneous Imaging Of Multiple Molecular Contrasts With Photoacoustic Ophthalmoscopy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2874.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a novel ophthalmic imaging technology based on photoacoustic ophthalmoscopy (PAOM) and lipofuscin autofluorescence (AF) that can simultaneously image the hemoglobin in the retinal blood vessels, and the melanin and lipofuscin in the RPE cells.
First developed by our group, PAOM is a branch of photoacoustic microscopy (PAM) which is an optical absorption-based imaging modality that detects laser-induced ultrasonic waves. Traditionally, PAM detects the ultrasonic waves generated in a sample by that part of the absorbed photons whose energy is converted to heat. However, apart from generating heat, the absorbed photons may also undergo other physical processes such as stimulating autofluorescence. Unfortunately, this effect of the absorbed photons is not utilized in conventional PAM, although they may provide important and complementary molecular contrasts of biological tissues. We investigated the feasibility of simultaneously imaging three distinctive molecular contrasts provided by the absorbed photons with single light source. In the integrated multimodal imaging system the PA and AF signals were detected by a high-sensitivity ultrasonic transducer and an avalanche photodetector, respectively. The wavelength of the illumination laser was 532 nm.
The system was first tested on imaging ocular tissue samples, including the RPE of a human donor eye and a pig eye, and the ciliary body of a pig eye. The acquired images provided information of the spatial distributions of melanin and lipofuscin in these samples. We then tested the system on imaging rat eye in vivo. Both pigmented and albino rats were imaged. High quality images of the retinal blood vessels and melanin and lipofuscin distribution of the RPE were successfully acquired simultaneously.
we have investigated the multiple molecular contrasts provided by the absorbed photons in biological tissues using an integrated PAOM and AF microscopy. Technique revealed interesting features of melanin and lipofuscin distribution, which were not seen before. Our study laid the foundation for future quantitative imaging of the distributions of lipofuscin and melanin in RPE in vivo, which are important for the research and clinical diagnosis of AMD.
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