Paving the way for human eye transplants

It seemed like a simple idea.

Design a device that will make it possible for a human eye to remain alive and functional outside of the body. At least for a few hours. And then a few days.

But the eye is a very complex organ. It is also connected to the brain, which is why successful human eye transplants still elude scientists and eye surgeons. It is one of four organs that have never been transplanted in humans, along with the brain, the spinal cord, and the inner ear hearing apparatus.

“The eye is unique because it requires a constant flow of oxygenated blood,” said Dr. David Tse, a professor of ophthalmology and orbital surgeon, who is now leading Bascom Palmer Eye Institute’s whole-eye transplant project with Daniel Pelaez, an associate professor of ophthalmology. “To ensure the viability of a donor eye, we have to maintain this flow, or perfusion, and avoid any loss of tissue oxygenation during the eye recovery and implantation process.”

That’s why Tse and Pelaez turned to Ashutosh Agarwal, a biomedical engineering faculty member and director of engineering and applied physics for the Desai Sethi Urology Institute. His lab creates devices called human organs on chips to discover novel treatments. Inspired by the extracorporeal membrane oxygenation (ECMO) device used for heart and lung bypass procedures, Agarwal and his students worked to recreate a smaller device for the eye.

The engineering team designed and produced a portable eye-ECMO machine that pumps oxygenated blood mixed with a unique solution in and out of the eye after it is removed from a donor. This helps keep the retina of the eye functioning properly, which is an important hurdle to overcome since the retina is responsible for sending signals to the brain to form images. Therefore, keeping the retina functional will allow a recipient to regain sight from a new donor eye.

As part of the eye-ECMO, the team is also utilizing the College of Engineering’s 3D Printing Facility of Excellence to create and refine a custom cannula. This tiny tube connects the primary vessel of the eye to the eye-ECMO machine, enabling constant circulation.

Then, the engineers also created an “eye-HOLDER,” so a recovered donor eye can be safely transported between the operating room and the laboratory for examination.

“This is a highly feasible engineering project that can really advance medical science forward,” Agarwal said. “This project also shows the value of true collaboration, where engineers can create products that may seem difficult to imagine, but when you work with a team of physicians, it comes together very nicely.”

And Agarwal’s team was able to see their innovation in action recently.

When the whole-eye transplant team received permission to recover its first eye from a donor, they were able to utilize the eye-ECMO device and the first iteration of the eye-HOLDER. The entire operation was made possible through a major grant from the U.S. Department of Health and Human Services’ Advanced Research Projects Agency for Health (ARPA-H) that the entire University team received in late 2024.

During the eye recovery surgery, Tse, along with neurosurgeons, scientists, engineers, and plastic surgeons, connected the eye-ECMO to the donor eye and placed it on the eye-HOLDER to keep it alive for several hours, where they were able to confirm tissue viability, or functionality. Seeing their success energized the team of 17 faculty members and additional staff members working on the project.

“I was entirely motivated when I left that night,” said Pelaez. “I saw the possibility of whole human eye transplants look a lot closer.”

It was one step forward in a complex puzzle that experts at Bascom Palmer Eye, the Miller School of Medicine, and the College of Engineering are working on to make whole-eye transplants possible. The project could take up to six years.

“Every step of the workflow went off exactly as designed, which is uncommon,” Tse said. “There were a few hiccups along the way, but all the major steps turned out as we planned. And without the eye-ECMO, it would not have worked.”

While they refine their techniques, researchers must now determine the best way to preserve the optic nerve—another significant challenge in the project. Then, the team must determine an optimal way to connect the optic nerve to a recipient. This is the most challenging obstacle to a successful eye transplant, Tse and Pelaez said.

Still, the eye-ECMO device as well as the eye-HOLDER is a critical piece in this project. When the team recently tested the first donor eye using fluorescent dye, they observed the dye circulating through the retina, aided by the eye-ECMO machine. In addition, optical testing of the eye removed from the donor confirmed the retina was functioning properly.  It was their first try.

“That was a big moment for the team because this type of procedure had never been performed at any site in the U.S.—and perhaps in the world,” Agarwal added. “No product like the eye-ECMO exists, but this was the proof that everything was working.”

The request to create such a device came to Agarwal’s lab a year ago, and he quickly realized it would be an ideal task. Agarwal, along with his doctoral students Emma Drabbe and William Raeter; master’s student Alexander Carrieri; lab technician Matthew Koble; and Atharva Dapse, an international summer intern from the Indian Institute of Technology Gandhinagar, immediately got to work.

They are now designing an eye-HOLDER with a gimbal mechanism for more stable organ transport, so that a donor eye is better protected when moving from one operating room to another, or even if it needs to be transported to a different hospital or a different city, as with other organ transplants.

“This could open up medical advancements in terms of whole-eye transplants to try and cure blindness,” Agarwal said. “I think it’s such a privilege for us as an engineering school to work with others across the University to drive innovation. It’s also a fantastic training experience for students to work alongside surgeons and to get feedback on their design.”