Vision in the dark: Researchers enable night vision by injecting particles

Study on mice first
Injection with nanoparticles allows night vision

Night vision without night vision devices: What sounds like science fiction may soon become a reality. The researchers are able to get the mice to see in the near infrared region – by injecting nanoparticles into their eyes. Similar nanoparticles could help people with poor eyesight and eye diseases.

People can only see light in a limited range of frequencies. Lower frequencies such as infrared are not visible to our eyes because photoreceptors do not respond to them. Technologies such as night vision goggles make this frequency range visible, for example by converting near-infrared radiation into visible light. But it could work without it, as the study shows.

Researchers at the University of Massachusetts Medical School and the University of Science and Technology of China have developed nanoparticles that mice can use to see at night. For their study, which was published in the journal “Cell”, the Gang Han team injected nanoparticles under the rodent retina. The bloodstream then transfers the nanoparticles to the eye. There, these so-called nano-antennas bind to photoreceptors, ie cells that are responsible for the perception of light. This allows the eye to respond to near infrared light that does not normally trigger a signal.

According to the study, a number of experiments showed that the mice did see this frequency range: For example, if near infrared light shone into the eye, only the pupils of the injected mice narrowed, while the pupils of the control groups did not respond. In injected mice, near-infrared light also activated the visual cortex, which is responsible for visual perception in the brain. Further investigation also showed that the ability to see at night was apparently not sight aggravated under visible light.

Night vision without complicated devices

Anchored particles expand the spectrum of visible light in such a way that animals can perceive near-infrared radiation from the invisible range, the researchers write. The brain then processes and interprets this information as an image. “This is happening without the help of complex equipment,” the study said. After the injection, the effect lasted up to two months.

In addition, this procedure appears to be relatively safe. Side effects were rare in the test animals. According to scientists, some animals developed corneal clouding after the injection, but it disappeared within a week.

“We therefore believe that this technology also works for the human eye,” said lead author Tian Xue. “In our experiment, the nanoparticles absorbed infrared light at a wavelength of 980 nanometers and converted it into light at a wavelength of 535 nanometers.” Light at 535 nanometers is visible to the human eye and is perceived as green.

According to scientists, it is conceivable that nanoparticles can be used not only to improve human vision, but also to treat visual defects and eye diseases. “With this research, we have greatly expanded the applications of nanoparticle technology. With a little help, we can be able to see all the hidden NIR and IR information in space that is not visible to the naked eye,” concludes Study Author Gang Han.

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