Medical advancements promise hope for Canadians with vision and hearing impairments
If the excitement in the research community is anything to go by, Canadians can expect a range of game-changing discoveries coming out of decades of vision and hearing health studies. Some of the findings represent a continued development of diagnostic tools and treatment options, while others have the potential to dramatically alter the way we address vision and hearing challenges.
There are many reasons for optimism for Canadians who are blind or partially sighted, says Mary Sunderland, director of research and education at the Foundation Fighting Blindness. “We know that research is a long-term investment, so when it is finding its way into our clinics, that’s an exciting time.”
Among the investigative areas where projects have progressed to the clinical trial stage are gene therapy and retinal prostheses. “Last year, the Foundation Fighting Blindness helped to support Canada’s first gene therapy clinical trial for a blinding eye disease,” says Dr. Sunderland. Another clinical trial the foundation has helped to bring to Canada focuses on the retinal prosthesis, the bionic eye, which uses a camera device and a retinal chip implanted into the eye.
The outlook is also promising for Canadians affected by hearing loss. Not only do they have access to constantly evolving hearing aid technology – which now analyzes, filters and prioritizes different sounds before relaying them to the ear – they can also benefit from a history of over 25 years of ear implants, says Manohar Bance, director of the Hearing Foundation of Canada’s research committee.
Dr. Bance, who is an ear surgeon and researcher at the Ear and Auditory Research (EAR) and Sensory Encoding andNeuro-Sensory Engineering (SENSE) research labs at Dalhousie University, explains that cochlear implants are electronic medical devices that carry out the functions of a damaged inner ear and relay sounds to the brain.
Due to the long period of developing cochlear implants, great strides have been made in ensuring that they convey a true representation of the auditory input.
Dr. Bance adds that developments in prostheses that bypass the middle ear – called bone conduction implants – help patients whose sound transmission to the inner ear is impeded.
“Both cochlear and bone conduction implants have shown good results, but we’re still dealing with damaged ears,” he explains. “Our ultimate goal is to restore normal hearing by restoring the organ of hearing – the inner ear – by regrowing it.”
Advances in stem cell and molecular biology and their implications for regenerative medicine are creating a lot of excitement and Dr. Bance says a number of related hearing health research initiatives are under way in Canada.
These developments mirror efforts in vision research, says Dr. Sunderland. While many diseases can lead to vision loss, they all have something in common – they cause a specific cell in the eye, the photoreceptor, to stop working. “The photoreceptor is the cell that detects and picks up light and transforms it into information that can be communicated to the brain,” she says.
Several research efforts focus on trying to preserve photoreceptors – to stop them from dying. “These are called neuro-protective approaches,” says Dr. Sunderland. “Another strategy focuses on restoring sight – to re-grow those cells in patients who have already lost their photoreceptors.”
Scientists in Ontario and Montreal are working on turning stem cells into photoreceptors that will be suitable for transplantation into the human eye, says Dr. Sunderland, who adds that the research is still in the pre-clinical trial stage and hasn’t been tested in humans. “Photoreceptors are very complicated cells,” she explains. “But we’ve moved on to clinical trials with retinal pigment epithelium (RPE) cells, which are much simpler cells.”
RPE cells don’t detect light, but they interact closely with photoreceptors in the maintenance of visual function. The clinical trials will determine whether replacing RPE cells can stop photoreceptors from deteriorating.
“A lot of people in the research community believe that regenerative therapies will be successful in the eye first,” says Dr. Sunderland. There are two reasons that make the eye suitable for testing these approaches: it’s an easily accessible part of the body and advanced imaging technologies allow doctors to closely monitor the cells.
While the eye is relatively easy to observe, the location of the ear presents diagnostic challenges, says Dr. Bance. “The ear is a bit of a black box – not like the eye, where you can shine a light through the cornea,” he explains. “The inner ear is embedded in the side of the head, surrounded by some of the densest bone in the human body.”
To reveal some of the ear’s mysteries, Dr. Bance’s lab is working on a diagnostic tool called optical coherence tomography (OCT). Similar to high-frequency ultrasound, OCT measures infrared light to produce high-resolution cross-sectional images revealing the architecture of the ear, “the bones of hearing,” says Dr. Bance.
As research produces advanced diagnostic tools, better implants and the promise of regenerating damaged cells, the future of Canadians affected by vision and hearing loss may be brighter. Dr. Sunderland says, “This work really matters for our patients and their families.”
The Foundation Fighting Blindness’s mission is to lead the fight against blindness by advancing retinal disease research, education and public awareness, and ultimately restore hope and sight (ffb.ca).
The Hearing Foundation of Canada, a national non-profit organization for funding medical research, public education and advocacy, is committed to eliminating the devastating effects of hearing loss by promoting prevention, early diagnosis, leading-edge medical research and successful intervention
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