Non invasive early diagnosis of any disease is a crucial step in prevention,treatment and decreasing the mortality rate. The purpose of this study is in vitro screening of neurodegenerative disease biomarkers, employing polarimetric detection methodology via ocular fluid. The eye is easily accessed by light for in vitro imaging and screening of diseases. The unique biomarkers exist in the ocular fluid for large groups of diseases, which can determine the presence and the stage of disease. For this research Amyloid, Vascular Endothelial Growth Factor and Glutamate biomarkers have been studied for in vitro detection of neurodegenerative diseases. The concentration elevation of any of these biomarkers may highlight the presence and progression rate of certain neurodegenerative diseases.
The potential of in vitro spectral and power analysis of optical biomarkers, under
two distinct geometries: a) Backscattered geometry; and b) Diffused reflectance geometry to detect unique optical signatures has been investigated. The copolarized and crosspolarized contributions were achieved by spectrometer and power meter, and the corresponding Degree of Linear Polarization (DOLP) were calculated. Backscattering geometry detected light from the surface and subsurface of the tissue (epithelium), therefore it was anticipated to be highly polarized. Diffused reflectance geometry detected light from deeper structures therefore, light contributions were mostly unpolarized due to multiple scattering. The combination of the data collected utilizing both geometries may reveal more inclusive information, by not solely reaching the surface of the target, but also deeper depth of the target.
Both spectral and power analysis of various concentrations of each biomarker
revealed a variation of the degree of linear polarization (DOLP) with increments in
biomarker concentration. The coefficient of variation between multiple measurements
was negligible and there was a consistency between repetitions. The statistical analysis of power and spectral responses illustrated a significant difference in DOLP by varying biomarker concentration, which can be utilized for early diagnosis of neurodegenerative diseases.