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H. F. Zhang, S. Jiao, A. A. Fawzi, C. A. Puliafito; Integrated Fiber-Optic Photoacoustic and Confocal Microscope for Ophthalmic Applications. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1020.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the potential of a multimodal technology to simultaneously image the optical absorption and scattering distributions in biological tissue toward ophthalmic applications. To demonstrate the feasibility of integrating photoacoustic microscopy with confocal scanning laser ophthalmoscope (cSLO) for fundamental studies of disease in retinal vessels and retinal pigment epithelium (RPE).
Photoacoustic microscopy is a high-resolution optical absorption based imaging technology that is capable of quantitatively imaging, for example, the total hemoglobin concentration and hemoglobin oxygen saturation in single blood vessel in vivo. We developed a laser-scanning optical-resolution photoacoustic microscopy (LSOR-PAM) to significantly increase the imaging speed by adopting the optical delivering and scanning mechanism used in OCT. By further employing a 2×2 single-mode fiber optical coupler for delivering the illuminating laser light and collecting the back reflected photons, a fiber-optic confocal microscope (FOCON) is integrated with the LSOR-PAM. Both the FOCON and the LSOR-PAM share the same laser source and the images from the two modalities are intrinsically registered. Multimodal imaging for both optical scattering and optical absorption is thus achieved simultaneously.
Both phantom imaging and in vivo imaging of Swiss Webster mice ears were performed and the complementary contrast mechanisms were well observed. In vivo imaging of blood vessels in the anterior segment of Swiss Webster mice eyes clearly revealed the microvasculature in the iris. Ex vivo imaging of excised human donor eye showed that sufficient contrast can be achieved by LSOR-PAM to resolve single RPE cells.
The significance of this work is that it exhibits the feasibility of integrating LSOR-PAM with the well-established cSLO for potential multimodal ophthalmic imaging based on a single light source. Although not demonstrated experimentally, this system is readily expandable to conduct confocal fluorescence microscopy by adding the appropriate band-pass filter and high-sensitivity optical detector (such as a photon multiplication tube), yet still sharing the same light source with LSOR-PAM. It is anticipated to find board applications in both fundamental research and clinical diagnosis of various eye diseases.
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