Treating Central and Peripheral Vision Loss: More Than Meets the Eye

Treating Central and Peripheral Vision Loss: More Than Meets the Eye

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By: Rachel Dragas

Faculty Affiliations:
Dr. Martin Steinbach, PhD
Senior Scientist, Toronto Western Research Institute and The Hospital for Sick Children
Distinguished Research Professor Emeritus, York University
Professor, Ophthalmology and Vision Sciences, University of Toronto
Director, Ophthalmology Research, University of Toronto
President, Vision Health Research Council of Canada
Full Member, Institute of Medical Science

An interview with Dr. Martin Steinbach on early detection and therapies for glaucoma and age-related macular degeneration.

Amongst many of his notable designations, Dr. Martin Steinbach is a senior scientist at Toronto Western Hospital, Professor of Ophthalmology at the University of Toronto, and President of the Vision Health Research Council of Canada. For the past 5 decades, Dr. Steinbach’s renowned work on abnormal eye movements and visual processes, as well as his advocacy for vision health and research in Canada have stood as a true testament to his passion and dedication in the field. His contributions have been recognized nationally and internationally; most notably, he received the 2008 Carl Kupfer Award from the Association for Research in Vision and Ophthalmology and has had the University of Toronto’s Department of Ophthalmology and Vision Sciences’ Annual Research Day Lecture named in his honour. Dr. Steinbach’s research not only focuses on plasticity of the developing visual system in patients with monocular eye enucleation, but also central and peripheral vision loss produced by diseases such as age-related macular degeneration (AMD) and glaucoma, respectively. His work is geared towards the development of effective techniques to measure residual visual acuity for patients with AMD as well as eye retraining strategies for utilization of functional retinal areas. More recently, his lab has also focused on early detection of impaired vection as an early indicator for glaucoma. I sat down with Dr. Steinbach to hear more about his passion for vision research and the progress of diagnostic applications and therapies for patients with retinal disease.

Can you tell us a bit about your background, training, and what brought you to this particular field of research?

I obtained my PhD from the Massachusetts Institute of Technology and have a degree in experimental psychology. I don’t identify as a psychologist, I identify as a systems neuroscientist—I do behavioural studies of the visual system. I came to Toronto in 1968 with a job offer at York University and, in 1971, while lecturing for an introductory psychology class, I noticed a student in the front row with eyes like Marty Feldman, the comedian. The condition he had is known as ‘alternating exotropia,’ a form of strabismus where both eyes are directed outward at alternate times. I hired the student as a research assistant and studied his eye movements. I soon realized that I couldn’t learn the clinical attributes of strabismus from books alone as I was always questioning the texts. After spending a year in San Francisco working with a famous eye muscle surgeon, I collaborated with another surgeon at The Hospital for Sick Children, where I looked at changes in the brains of patients with rotated eyes and how the brain stays informed about these movements. I was able to glean understanding on how vision works by understanding how it can go wrong. My collaboration with Dr. Brenda Gallie, who is world famous for treating unilateral retinoblastoma, enabled me to study the competition that occurs between the eyes during development—if it’s interrupted by a cataract, droopy lid, or unequal refractive error, for example, the child develops amblyopia (lazy-eye) and the brain doesn’t wire up properly. During development in enucleated children, the brain gets rewired to have the single eye take up space and computing energy that would normally be distributed between both eyes. Enucleated children have visual functions that are superior to those with monocular vision but equal to those with normal binocular vision. This is an example of sensory plasticity.

What rehabilitative strategies can be utilized by patients with macular degeneration?

Macular degeneration is a condition where foveal or central vision becomes damaged and nonfunctional. Patients with this disease, however, retain function in their retinal periphery. In the absence of central vision, patients develop alternate points of fixation in eccentric parts of the retina, termed ‘preferred retinal loci.’ However, if a patient has a preferred retinal locus at the horizontal edge of a scotoma (blind spot with no photoreceptors), for example, they cannot read. If we can get these patients to change which part of the retina they use, essentially relocating their preferred retinal locus, they are able to read again and acquire better fixation stability. We train patients, using biofeedback methods, to move the fixation point to a position that would allow horizontal movement to seeing parts of retina. Unfortunately, this requires an expensive piece of equipment (a microperimeter), which is not readily available or easy to use. An alternative technique, called ‘perceptual learning’ is just as effective and has improved functioning in many patients. We ask patients to read text and encourage them to look above or below the script, allowing images to be picked up by a working part of the retina. They can develop a good point of fixation using this method. The challenge is getting this technique out into wider application given the time-consuming process of training patients, which is often impractical for most physicians and ophthalmologists. It would be ideal to create an online app for automation of these techniques, so that patients can train themselves in the comfort of their homes.

Can you tell us more about the technology that you are utilizing for early detection of glaucoma?

Contrast to macular degeneration, glaucoma is an eye disease that first affects peripheral vision. Despite this, most people don’t realize that their eyesight is impaired until their central vision is affected. The retinal periphery is necessary for orientation in space. Vection is a perceptual phenomenon where, when a large part of the visual field moves, the viewer feels like they have moved while the world remains stationary. Using Oculus Rift virtual reality technology, our lab can extract information from peripheral visual function and test whether impaired vection is an early indicator for glaucoma. This provides an opportunity for early treatment and prevention of vision loss.

What is the most rewarding part of your job?

The most rewarding part of my job is training young scientists but also serving as a bridge between basic and clinical research. I’m trained as a basic scientist, but I’ve become sufficiently embedded in ophthalmology. For the past 11 years, I’ve written a bi-monthly column in the Canadian Journal of Ophthalmology called Cyclops. In every issue, there are 6 experimental studies that I briefly summarize and state the importance of for my ophthalmologist colleagues. There’s lots of interesting basic research that clinicians should be aware of so I’m particularly proud of Cyclops. In addition to this, I serve on the Canadian National Institute for the Blind research committee, I’m the Chair of Medical Advisories for the Foundation Fighting Blindness, and an advocate for vision research in Canada.

What do you think is the future of research in vision science?

Long term, the opportunity to see dead photoreceptor cells replaced through stem cells or gene transplants—this would cover a lot of diseases including macular degeneration and diabetic retinopathy. However, in the short term our efforts should also be focused on rehabilitation for patients currently experiencing vision loss, as there are still treatment strategies that can be implemented to prevent further vision loss and improve quality of life.

What advice can you give to current graduates?

Aside from following your dreams and enjoying your work, be open to opportunities that exist outside of academia. Appreciate the fact that you are acquiring numerous skills that have application outside of the academic world and that should give you optimism about being gainfully employed in the future.