A Life-Changing View on Alzheimer’s

While there's currently no test that can definitively diagnose Alzheimer's, new methods of studying the eye could help catch the disease early on.

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Currently, there is no diagnostic test that definitively identifies individuals living with Alzheimer’s. The Alzheimer’s brain contains deposits of a protein called amyloid beta, which can only be tested following death. However, Alzheimer’s patients experience worsening difficulty with memory, language, and self-care, and an early diagnosis can mean more effective medical intervention. Melanie Campbell, professor of physics at the University of Waterloo, is looking for ways to get an early Alzheimer’s diagnosis by using the living eye as a window to the brain.

The brain is difficult to view directly, but the eyes are easier to access for medical imaging because they are transparent to light. Like the brain, the retinas at the back of the eyes are also part of the central nervous system. Campbell has detected amyloid beta deposits in the neural tissue of the retina, which is the light sensing layer at the back of the eye.

Campbell notes, “If we can develop this non-invasive method of doing the imaging which would be readily accessible to people, then early diagnosis of Alzheimer’s might be possible and that’s very important… it gets the patient involved in their care when the disease is still at any early stage. It also means that drugs that work best at early stage of the disease to slow down its progression can then be used.”

Although these tests are not yet being used on living patients, Campbell has already worked with donor tissue collected from patients after death. She knows that amyloid deposits are large enough to be imaged through the eye, and that they are usually present in individuals with confirmed Alzheimer’s disease. This makes a compelling case for early Alzheimer’s testing in the living eye.

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Prof. Melanie Campbell is currently a Professor in the Department of Physics and Astronomy, University of Waterloo and is cross-appointed to the School of Optometry and Vision Science. She obtained a B.Sc. degree in Chemical Physics from the University of Toronto and an M.Sc. degree in Physics from the University of Waterloo. An interest in the optical properties of the eye led to a Ph.D. from the Australian National University awarded jointly by the John Curtin School for Medical Research and the Research School of Physical Sciences. After 2 years as a postdoctoral fellow at CSIRO in Australia, a University Research Fellowship from the Natural Sciences and Engineering Research Council of Canada enabled Prof. Campbell to join the University of Waterloo. She currently pursues research in optics of the eye, accommodation, presbyopia, ophthalmic corrections and ophthalmic diagnostic instruments. Her current research interests include defining the quality of the optical image formed on the retina; studying the optical properties of the crystalline lens and eye during development and in the older eye and integrating adaptive optics and polarization methods into instruments which image the rear of the eye. Her basic research led to improved quality of clinical images of the retina of the eye. The Waterloo confocal scanning laser ophthalmoscope that was developed by Prof. Campbell’s group gave the first live images of the cones of the human eye. Prof. Campbell is a Fellow of the Optical Society of America and received the 2004 Rank Prize in Optoelectronics for studies of the gradient of refractive index in the crystalline lens. In 2014, Prof. Campbell was awarded the CAP/INO Medal for Outstanding Achievement in Applied Photonics.