Reviewed by Lexie CornerApr 17 2025
In a study funded by the National Institutes of Health, researchers at Brown University suggest that gold nanoparticles (microscopic gold particles thousands of times thinner than a human hair) could eventually be used to help restore vision in individuals suffering from macular degeneration and other retinal disorders.
Image Credit: Brown University
The study showed that nanoparticles injected into the retina can successfully stimulate the visual system and restore vision in mice with retinal diseases. The findings suggest that a new type of visual prosthesis, using nanoparticles along with a small laser device worn in glasses or goggles, could potentially help people with retinal diseases regain their sight.
This is a new type of retinal prosthesis that has the potential to restore vision lost to retinal degeneration without requiring any kind of complicated surgery or genetic modification. We believe this technique could potentially transform treatment paradigms for retinal degenerative conditions.
Jiarui Nie, Study Lead and Postdoctoral Researcher, National Institutes of Health
Nie conducted the research in the lab of Jonghwan Lee, an associate professor at Brown’s School of Engineering and a faculty affiliate at the Carney Institute for Brain Science, who oversaw the study as senior author.
Millions of people worldwide suffer from retinal diseases such as retinitis pigmentosa and macular degeneration. These conditions damage photoreceptors, which are light-sensitive cells in the retina that convert light into electrical pulses. Bipolar and ganglion cells, located further along the visual pathway, process these pulses and transmit the information to the brain.
This new method bypasses damaged photoreceptors by injecting nanoparticles directly into the retina. When infrared light is focused on the nanoparticles, they generate a small amount of heat, stimulating the bipolar and ganglion cells in the same way photoreceptor pulses would. Since macular degeneration primarily damages photoreceptors while leaving ganglion and bipolar cells intact, this approach may offer a way to restore vision.
In the study, the researchers tested the nanoparticle method in both mouse retinas and live animals with retinal diseases. They injected a liquid nanoparticle solution into the retinas, then projected shapes onto them using patterned near-infrared laser light. By monitoring cellular activity with calcium signals, the team confirmed that the nanoparticles successfully stimulated bipolar and ganglion cells in patterns corresponding to the projected shapes.
The experiments showed no detectable harmful effects from either the nanoparticle solution or laser stimulation, based on metabolic markers for inflammation and toxicity.
Probes confirmed that laser activation of the nanoparticles increased activity in the mice’s visual cortices, indicating that visual signals were being processed by the brain. The researchers believe this suggests that vision was largely restored, which could provide a foundation for applying similar technologies to humans in the future.
They aim to develop a system for human use that integrates nanoparticles with a laser system installed in goggles or glasses. The goggles would have cameras to capture visual information from the environment, which would then control how the infrared laser is patterned. These laser pulses would activate the nanoparticles in the retina, potentially enabling vision.
This approach mirrors a method approved by the FDA for human use several years ago. That method combined a camera system with a small electrode array, which was surgically implanted in the eye. According to Nie, there are three key advantages to the nanoparticle approach.
First, it is significantly less invasive.
In contrast to surgery, “an intravitreal injection is one of the simplest procedures in ophthalmology,” Nie explained.
There are also practical benefits. The previous method's resolution was limited by the electrode array, which had around 60 pixels. Since the nanoparticle solution covers the entire retina, the new method could potentially cover the full field of vision.
Additionally, because the nanoparticles respond to near-infrared light rather than visible light, the system would not necessarily interfere with a person's remaining vision.
While further research is needed before this approach can be tested clinically, Nie noted that the preliminary findings show that the method is feasible.
Nie added, “We showed that the nanoparticles can stay in the retina for months with no major toxicity. And we showed that they can successfully stimulate the visual system. That’s very encouraging for future applications.”
The study was supported by the National Eye Institute of the National Institutes of Health (R01EY030569), the China Scholarship Council, the Saudi Arabian Cultural Mission, and South Korea's Alchemist Project Program (RS-2024-00422269).
Co-authors include Professor Kyungsik Eom from Pusan National University, Brown Professor Tao Lui, and Brown students Hafithe M. Al Ghosain, Alexander Neifert, Aaron Cherian, Gaia Marie Gerbaka, and Kristine Y. Ma.
Journal Reference:
Nie, J. et al. (2025) Intravitreally Injected Plasmonic Nanorods Activate Bipolar Cells with Patterned Near-Infrared Laser Projection. ACS Nano. doi.org/10.1021/acsnano.4c14061