Page 8 - envision01-2021
P. 8

Cover Story

                       R E SE AR CH

        / Students from the Waterloo School of Optometry and Vision Science students examining eyes. /

                                          / Dr. Ben Thompson attaching non-invasive brain stimulation electrodes to a study participant.  /
                                         A research team, led by Dr. Ben Thompson,  between neurons that contribute to
                                         professor, School of Optometry and Vision  crowding,” explains Dr. Thompson.
                                         Science, University of Waterloo, found
                                         that a 20-minute session of transcranial   In the study, task performance returned to
                                         direct current stimulation (tDCS) in people  baseline after 24 hours, he noted. “We are
                                         with normal vision reduced crowding. The   exploring whether repeated sessions can
                                         researchers hope that this finding could  lead to longer-lasting improvements.”
                                         be the first step towards using tDCS as a
                                         treatment for patients with AMD.    Although  tDCS  is  still  an  experimental
                                                                             form  of  brain  stimulation,  it  offers
                                                                             several advantages over existing macular
            “   Our theory is that       fects of macular degeneration arose from  degeneration treatments: it is cheap,
                                         The idea of using tDCS to reduce the ef-
                                         Dr.  Thompson’s discussions  with Raj  non-invasive, painless, and safe.
             anodal tDCS acts to
                                         Raveendran, a former PhD student, who is
           reduce inhibition within      now with the Envision Research Institute   Another treatment, perceptual learning,
                                                                             helps patients learn to reduce the effects
                                         in Wichita, KS.
                                                                             of  crowding  by  performing  visual  tasks
         the visual cortex and this      “Raj was planning a project in the area  repeatedly. However, this typically requires
        effect alters the inhibitory     of low vision rehabilitation for his   intensive training, which may be a
            connections between          postdoctoral work and we talked about  barrier for some patients. “That’s why
                                         some of my previous experiments   this discovery is so promising,” says Dr.
        neurons that contribute to       demonstrating that  tDCS  could improve  Thompson, who notes that tDCS can also
                                                                             be combined with perceptual learning
                                         vision in amblyopia (lazy eye).
                         crowding     “  “Other  studies  demonstrated that  tDCS   techniques.  
                                         could improve peripheral vision in people   The results of Dr. Thompson’s research lay
                                         with normal sight, (so we) decided to   the foundation for future work investigating
                                         explore its potential to improve peripheral   whether anodal tDCS may be useful as a
                                         vision in patients with central vision loss.  visual  rehabilitation tool  for individuals
                                         Raj’s  work  as a  postdoctoral  fellow  has  with central vision loss who rely on
                                         demonstrated that the idea has promise.”  peripheral vision, he says. “If we find
                                                                             improvements in reading, we will expand
                                         The researchers found that in people with  our research to other visual functions,
                                         normal vision, anodal tDCS, which excites   such as face recognition and recognising
                                         neuronal activity, reduced one aspect  and localizing objects. We will also explore
                                         of crowding called lateral inhibition in   how best to utilize anodal tDCS within the
                                         peripheral vision. In a case series of three  clinical environment.”
                                         patients with central vision loss, they
                                         found the same positive effects.    Unfortunately, that research is on hold due
                                                                             to the pandemic. However, Dr. Thompson
                                         “Our theory is that anodal tDCS acts to   and his team hope to have results within
        / Students from the University of Waterloo School of Optometry and Vision Science conducting   reduce inhibition within the visual cortex and  one to two years, depending on when their
                                  eye exams. . /
                                         this effect alters the inhibitory connections   work can resume.

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