Hyperspectral Microscope for Drusen Phenotyping

DESCRIPTION (provided by applicant): The demonstration of a Fourier-transform hyperspectral microscope for high resolution spectral ex vivo characterization of human retinal tissue is the aim of this project. The spectral reflectance and intrinsic fluorescence nature of normal and pathological retinal tissue must be established without the interfering effects of the intervening ocular media. This motivates the immediate goal of integrating the Fourier-transform imaging spectrometer (FTIS) to a microscope. A hyperspectral microscope may be used in many areas of biological and medical research; tissue classification (normal vs. pathological) and characterization, detection of bacteria, gene identification, chromatin distribution, drug safety and efficacy, molecular imaging, and countless other applications. The Fourier-transform technology provides for a large number of highly resolved spectral bands simultaneously spatial at each pixel in the scene. Since fluorescence intensities are several orders of magnitude less than the reflectance signal, it is necessary to use a spectrometer with the highest possible sensitivity and wavelength selectivity. The FTIS has the advantage over traditional dispersive-based spectrometers in that entrance aperture and spectral resolution are decoupled. Thus, the slit can be increased to allow more light into the system without reducing spectral resolution. Further, because the FTIS is a constant wave number device, it offers improved spectral resolution in the visible to short wave infrared bands for a given detector size over conventional dispersive spectral imagers. Finally, the spatially modulated device collects all spectral data at once, avoiding any issues with spectral registration that otherwise occur. The six-month Phase I project will demonstrate the sensitivity of the hyper-spectral imaging methodology for spectrally phenotyping drusen in age-related macular degeneration (ARMD) eyes. Our approach builds on Kestrel's existing hyperspectral instruments and software, developed through Department of Defense. High spectral (2-4 nm) and spatial resolution images will be collected of histological specimens from two normal donor eyes and two eyes with clinical evidence or pre-mortem diagnosis of ARMD. The integrated system will be calibrated and tested. Illumination requirements for recording fluorescence will be established. A detailed, multi-source data set will be produced consisting of measurements of reflectance and transmission spectra, and intrinsic fluorescence spectra.