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.

Medical hyperspectral imaging: a review

“…An HSI system has been combined with many other techniques, such as laparoscope, 46 colposcope, 34 fundus camera, 76,113,114 and Raman scattering, 115 in order to leverage the key benefits of each instrument individually and provide more useful information for disease diagnosis and treatment. The most common combination is with microscope 35,38,85,[116][117][118][119][120][121] or confocal microscope, 122 which has been proved useful in the investigation of the spectral properties of tissue.…”

“…180 Cell protein cytochrome-c has been identified as a key signaling molecule in the degeneration processes and apoptosis. Schweizer et al 121 developed an HSI system to collect spectroscopic data, which provided information about the oxidative state of cytochrome-c during oxidative stress for detection of AMD. Fawzi et al 76 applied CTIS to quantify the macular pigment (MP) in a group of healthy eyes in vivo.…”

Hyperspectral Imaging and the Retina: Worth the Wave?

“…Such information is valuable to diagnose and monitor various ocular diseases including agerelated macular degeneration (ARMD), glaucoma, and diabetic retinopathy. [23][24][25][26][27][28][29][30][31][32][33] For further adoption of HSI technology in ophthalmologic research, it is important to explain the underlying imaging principles and describe the current relevant techniques, allowing for the identification of gaps and directions for future research and practice. Retinal HSI for ophthalmology has been documented before, but only included in reviews that analyzed the entire medical field or in manuscripts that date from several years ago.…”

Snapshot hyperspectral retinal imaging using compact spectral resolving detector array

“…Retinal diseases are often accompanied by retinal pathological changes that alter the light scattering and/or absorption properties in retinal tissues . Many important biomarkers are tightly related to optical scattering and absorption spectra of retinal vessels and their surrounding tissues, including retinal vessel oxygen saturation (sO 2 ), macular pigment absorption, and cell protein oxidative state . Hyperspectral retinal imaging provides a noninvasive way to monitor these retinal biomarkers, and could potentially benefit diagnosis and therapeutic monitoring of several retinal diseases, such as diabetic retinopathy, age‐related macular degeneration, and glaucoma .…”