The Waterloo Institute for Nanotechnology Member Seminar Series is a monthly event that showcases the incredible work by faculty members, students and researchers in the institute. This seminar series will highlight Prof. Melanie Campbell and two of her students - Peter Neathway and Yunyi Qiu. The Campbell optic's lab researches the human eye, optical systems and disease diagnosis.
Using the retina to look into the brain in Alzheimer’s disease
Professor Melanie Campbell
Department of Physics and Astronomy & School of Optometry and Vision Science
The retina forms as an outpouching of the brain and, like the brain, contains neural cells. Thus, we expected and have confirmed that deposits of amyloid protein form in the retinal neural cell layers, analogous to their formation in the brain early in the Alzheimer’s disease (AD) process. Our patented technique, using polarized light without a dye, can identify presumed amyloid deposits with 100% sensitivity in retinas of those with a diagnosis of AD. In addition, the number of deposits predicts the severity of amyloid pathology in the brain and the overall severity of the disease pathology. This technique holds great promise as an earlier, less invasive, readily available diagnostic which will enable less expensive testing of promising treatments and earlier, more accurate disease diagnosis.
Multifractal analysis for differentiating retinal amyloid deposits associated with different pathologies
Masters of Science, Physics - Nanotechnology student
Amyloid-laden deposits with intrinsic polarization signals form in the retina in association with Alzheimer’s disease. Similar deposits also seem to form in association with other ocular conditions, like age-related macular degeneration, and in association with various brain pathologies. Linear retardance is the polarization signal that provides the strongest contrast between deposits and retinal surround. Multifractal analysis (MFA) is a means of representing the complexity/texture of a set as a spectrum and has been used in a variety of biomedical imaging applications. This work demonstrated that MFA of linear retardance maps could statistically differentiate between deposits associated with various pathologies, as could polarization signals. These results indicate the potential of MFA and polarimetry for diagnostic purposes.
Predicting the positivity for thioflavin fluorescence of retinal deposits found in association with Alzheimer’s disease by their polarimetric properties
Master of Science, Physics student
Alzheimer’s disease (AD) is a neurodegenerative disease which leads to cognitive impairment and ultimately death. Amyloid deposits composed of misfolded amyloid-β protein serve as the hallmarks for AD. Thioflavin is a fluorescent marker for amyloid, including amyloid-β. Here, we present three machine learning methods with the aim of predicting when retinal deposits found in association with AD are positive in thioflavin fluorescence from their interaction with polarized light, without using a dye. Two oversampling strategies were applied to overcome data imbalance. This research demonstrated that thioflavin positivity of retinal amyloid deposits can be predicted from their polarimetry images. These results indicate polarimetry is a promising dye free method of detecting amyloid deposits in ex vivo retinal tissue.