Electricity for the eyes

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If people and objects appear to be erased from the field of vision, glaucoma may be behind it. At an advanced stage, there is little that can be done about loss of vision. But now there is hope: AC therapy seems to be able to reverse the visual impairment, at least partially.

The aqueous humor circulates in the human eye between the lens and the cornea. It supplies the cells with oxygen and nutrients. In glaucoma - as the glaucoma is also called - the aqueous humor does not drain properly. The result: The pressure inside the eye increases. It constricts the blood vessels that supply the nerve cells in the optic nerve. If this condition persists for a long time, the nerves die. People see increasingly worse.

The broken nerve cells can no longer be revived. But the others who are still healthy or only slightly damaged can be encouraged to perform at their best with a trick. "Light alternating current impulses activate the nerve cells," explains Professor Bernhard Sabel from the University of Magdeburg to

Communication strengthens connections

There is a simple principle behind this: In the brain there are billions of nerve cells that are linked to one another. They communicate by relaying electrical signals to a neighboring nerve cell. When two nerve cells talk to each other a lot, the connection between them is strengthened. “They react when only little information arrives,” says Sabel.

It is precisely this phenomenon that Sabel and his colleagues use for the current therapy, which they have now investigated in a clinical study. The current impulses ensure that the nerve cells communicate more with one another. "They act like a kind of signal to fire the nerve cells," says the scientist. This makes the cells highly active and also transmits weak signals to the next cell. The electricity also wakes up slightly damaged cells that are in a kind of hibernation. "Because they are not doing so well, they no longer take part in the lively information traffic in the brain - unless they are stimulated to do so."

Nerve jogging on the couch

The nerve cells in the visual center could also be actively stimulated - through consistent visual training. “But you have to practice an hour every day for many months,” says Sabel. Older patients in particular are often no longer able to do this because it is simply too exhausting for them. "Electric therapy is a much simpler and more effective method."

And it has an additional effect: it coordinates the brain waves in the visual center. These can be thought of as waves. If a wave crest meets a wave trough, they cancel each other out. Due to the current impulse, the mountains of these waves run more parallel and intensify. "It is possible that a weak light that the patient would otherwise no longer consciously perceive again generates a signal in the brain and that he sees it again despite glaucoma," says Sabel.

Points of light in the fog

A total of 82 patients with advanced glaucoma participated in Sabel's study. For ten days they received short electrical pulses from electrodes placed on the skin around the eye. Half received the correct therapy, with a frequency of eight to 25 hertz. The other half received only one pulse per minute. It served as a control group because this stimulation should have almost no effect.

Sabel and his colleagues then checked the patients' vision and again after two months. The patients had to press a button as soon as they could see a point of light on a gray background.

A quarter improvement

The result was promising: the eyesight of the patients who had received the AC therapy improved by almost a quarter, in the control group by only 2.5 percent. In the areas of the visual field that were already particularly badly affected by the eye disease, eyesight increased by as much as 59 percent.

Progress persisted two months after therapy. Sabel and his colleagues have not yet systematically examined whether the eyes will also benefit in the long term. "Some patients report that they can read better even after three years, with others the effect slowly diminished again." The scientist's assumption: If the patient also uses the improvement in everyday life, it is retained because the circuits in the brain be activated again and again. "It's like a foreign language, if you need it on vacation or at work, don't forget the vocabulary either."

Source: Sabel B. A. et al .: Alternating Current Stimulation for Vision Restoration after Optic Nerve Damage: A Randomized Clinical Trial.PLOS ONE, June 29, 2016 DOI: 10.1371 / journal.pone.0156134

AC therapy for glaucoma patients is already being carried out at the Savir Center in Magdeburg.

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