Golden Eye: Gold Nanoparticles may help people recover their vision one day

A new study by researchers at Brown University suggests that gold nanoparticles (a microscopic bit of gold thousands of times thinner than human hair) are used to restore vision in people with macular degeneration and other retinal disorders.

In a study published in the Journal ACS Nano, the researchers showed that nanoparticles injected into the retina can stimulate the visual system normally and restore vision in mice with retinal damage. The findings suggest a new type of visual prosthesis system in which nanoparticles used in conjunction with small laser devices worn on pairs of glasses and goggles could one day be re-exposed by people with retinal disorders.

“This is a new type of retinal prosthesis that has the potential to restore lost vision to retinal degeneration without the need for any kind of complex surgery or genetic modification,” said Jiarui Nie, a doctoral researcher at the National Institutes of Health who led the study while earning her PhD. In brown. “We believe this approach can potentially transform the therapeutic paradigm of retinal degeneration conditions.”

Nee worked while working in the lab of John Wang Lee, an associate professor in the Faculty of Engineering at Brown and a faculty member at Brown’s Kearney Institute of Brain Science.

Retinal disorders such as macular degeneration and pigment retinitis affect millions of people in the United States and around the world. These conditions damage photosensitive cells in the retina, called photoreceptors. Photoreceptors are “rods” and “cones” that convert light into small electrical veins. These pulses stimulate bipolar cells and other types of cells that further raise the visual chain, called ganglion cells, and process photoreceptor signals and send them along the brain.

This new approach uses nanoparticles injected directly into the retina to bypass damaged photoreceptors. When infrared light is focused on nanoparticles, it produces a small amount of heat that activates bipolar and ganglion cells in roughly the same way as photoreceptor pulses. Disorders like macular degeneration affect photoreceptors primarily while leaving bipolar and ganglion cells intact, so strategies can restore lost vision.

In this new study, the researchers tested the nanoparticle approach in mouse retina and living mice with retinal damage. After injecting the liquid nanoparticle solution, the researchers used a pattern of near-infrared laser light to project the shape onto the retina. Using calcium signals to detect cell activity, the team confirmed that the nanoparticles were exciting bipolar and that the pattern of ganglion cells matched the shape projected by the laser.

This experiment showed that neither nanoparticle solution nor laser stimulation causes detectable adverse side effects, as indicated by metabolic markers of inflammation and toxicity. Using the probe, the researchers confirmed that laser stimulation of the nanoparticles caused an increase in activity in the visual cortex of mice. That’s a sign that the vision has at least been restored, according to researchers, and a good sign of the possibility of similar technology being translated into humans.

For human use, researchers envision a system that combines nanoparticles with laser systems attached to glasses or goggles. The camera inside the goggles collects image data from the outside world and uses it to drive the pattern of the infrared laser. Laser pulses stimulate nanoparticles in people’s retina and allow them to see.

This approach is similar to that approved by the Food and Drug Administration for human use several years ago. The older approach combined a camera system with a small array of electrodes surgically embedded in the eye. According to NIE, the nanoparticle approach has several important benefits.

First of all, it is much less invasive. In contrast to surgery, “Intravitreal injection is one of the simplest procedures in ophthalmology,” Nee said.

It also has functional advantages. The resolution of the previous approach was limited by the size of the electrode array, that is, the size of 60 square pixels. Since nanoparticle solutions cover the entire retina, a new approach could cover someone’s complete field of vision. Additionally, nanoparticles react to near-infrared light, in contrast to visual light, so the system does not necessarily interfere with residual vision that humans may hold.

Nee said that further work should be done before attempting the approach in a clinical setting, but this early study suggests that it is possible.

“We have shown that nanoparticles can stay in the retina for several months without any major toxicity,” Nee said of the study. “And they showed they can stimulate the visual system well, which is extremely encouraging for future applications.”