Page 8 - envision01-2021

Cover Story
R E SE AR CH
/ Students from the Waterloo School of Optometry and Vision Science students examining eyes. /
“ Our theory is that
anodal tDCS acts to
reduce inhibition within
the visual cortex and this
effect alters the inhibitory
connections between
neurons that contribute to
crowding “ “Other studies demonstrated that tDCS
/ Students from the University of Waterloo School of Optometry and Vision Science conducting
eye exams. . /
8 / JANUARY - FEBRUARY 2021 / www.ENVISIONMAGAZINE.ca /
/ 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
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.
Raveendran, a former PhD student, who is
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
“Raj was planning a project in the area repeatedly. However, this typically requires
of low vision rehabilitation for his intensive training, which may be a
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.
demonstrating that tDCS could improve Thompson, who notes that tDCS can also
be combined with perceptual learning
vision in amblyopia (lazy eye).
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
reduce inhibition within the visual cortex and one to two years, depending on when their
this effect alters the inhibitory connections work can resume.