Hyperspectral imaging - A new modality for eye diagnostics

Abstract

Age-related-macular-degeneration (AMD) is the leading cause of blindness in people over 65 years in the western society. The prevalence of AMD arises during old age, due to the generally increased oxidative cell stress. In case of AMD, the symptoms include irreversible degenerative cell processes, like apoptosis, and morphological changes in the eyebackground. Currently, there are no effective treatments to regenerate the visual function of patients with this disease. Therefore, it is essential to develop methods for an early detection of AMD in order to stop the degeneration processes. The cell protein cytochrome-c (cyt-c) has been identified as a key signalling molecule in degeneration processes and apoptosis. In its oxidized state, the protein exhibits several strong absorbance bands in the spectral range between 400 nm and 700 nm. Using hyperspectral imaging spectroscopy, the oxidative state of cyt-c can be detected in real time, without the need for additional biochemical markers, in cell cultures in vitro. Initial studies were performed with two systems. The first system is a high performance uv/vis imaging spectrometer coupled to a microscope. The second system is a model representing the optical properties of a human eye. Reflected light from the eye background was collected in an optical fibre and transferred into a highly sensitive linear photodiode spectrometer. The collected spectroscopic data provide information about the oxidative state of cyt-c during oxidative stress. By using these spectral signals, we will be able to draw conclusions about the biochemical status and degeneration process in cells. The results demonstrate that reflection spectroscopy has a high potential for developing a fast, non-invasive spectroscopic system to detect the early state of AMD.