Twenty Days Of Training Can Shrink Your Blind Spot And Possibly Help With Vision Impairment

Blind spot
Want to shrink your blind spot? It might take just 20 days of training. Ahmed Sinan, CC BY 2.0

However hard we try, there’s no way for us to get rid of our physical blind spot, the frustrating phenomenon that only occurs because the area where our optic nerve passes through the retina is devoid of photoreceptor cells (invertebrates such as octopi have no such problem). Without these cells, there’s no light for the brain to process, and the area of vision that would be normally projected on that exact spot in the retina is left in darkness.

According to a small study published Monday in Current Biology, however, we might be able to shrink it.

The study authors recruited 10 people to take part in a 20-day long training regimen. They were presented with the image of a ring centered around the very edge of the blind spot in one eye, which could expand or decrease in size. The authors then sent a wave of dark and light bands through the image, asking the participants to correctly tell them which direction these waves were moving in; additionally, they were asked about the ring’s color.

Being able to adjust the ring’s size so that the subjects could accurately figure the direction of the wave about 70 percent of the time, the authors slowly but surely trained them to see better.

"We did not confidently expect to see much reduction in functional blindness, as you can never develop photosensitivity within the blind spot itself," said study author Dr. Paul Miller, of the University of Queensland in Australia, in a statement. "You can only enhance sensitivity at the blind spot periphery, but this proved sufficient to bring about a 10 percent reduction in functional blindness."

And even more notably, this effect wasn’t seen in the untrained eye, suggesting their subjects’ improvement wasn’t simply the result of practicing the test over and over again — instead the training seemingly boosted “the response gains of neurons with receptive fields that partially overlap, or abut, the physiological blind spot, thereby enhancing sensitivity to weak signals originating primarily from within the functionally-defined region of blindness.”

That improvement might not seem like much to most people, since the blind spot largely goes unnoticed, but it could mean a great deal for those suffering from progressive vision impairment. It could especially function as a tool for vision recovery in conjunction with developing technologies like stem cell therapy.

Miller and his colleagues hope to further improve their training program, first with normally sighted people, then with individuals suffering from age-related macular degeneration (AAMD), which gradually can reduce vision to the point of blindness due to retina damage.

Source: Miller P, Wallis G, Bex P, et al. Reducing the size of the human physiological blind spot through training. Current Biology. 2015.

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