Then, the researchers placed electrodes on the people's scalps, above the area of the brain that processes visual information, to dole out the electrical currents. The mild current was applied for 20 minutes.
After receiving the electrical stimulation, the participants were asked to repeat the vision test. About 75 percent of the people showed measurable improvement in their visual acuity for about 2 hours following the brain stimulation. The remaining 25 percent did not experience any improvement, the researchers found.
The researchers also explored whether people's improved performance on the vision test would translate to improvement in a real-world vision task. In this part of the study, the researchers asked the participants to read a standard eye chart. They found that people's vision improved by one to two letters, on average, compared with their results on the test prior to the electrical stimulation. However, the results varied from person to person, the researchers said.
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The scientists also looked at what happened when they changed the placement of the electrodes on a person's scalp. They found that the electrodes had to be positioned specifically over the brain's visual processing center in order to affect the people's eyesight. In other words, the effect wasn't simply a response to the electrical current anywhere in the brain but rather a response to the stimulation of a specific area of the brain.
One day, this research might point toward a way to use brain stimulation to treat people with severe eye disorders that can result in vision loss, such as glaucoma, the researchers said. But they added that much more research is needed first.
Woodman cautioned that people should not try to zap their brains at home. "If you hook this thing up wrong, you can make vision worse," he told Live Science.
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