Recent studies show that human eyes can function outside the body for up to 10 hours after death, doubling previous records. By supplying blood and oxygen to donor eyes, researchers have ensured that the eyes can still respond to light, maintaining structural integrity and health.

“This study marks a significant advance toward the potential for whole-eye transplantation,” states Thomas Johnson of Johns Hopkins University in Baltimore, Maryland, who was not involved in the research. “Achieving a mild response outside the body is a remarkable milestone.”

Over 1 million people in the UK experience blindness or low vision. Irreversible eye conditions like age-related macular degeneration impact the retina, the light-sensitive tissue at the back of the eye.

Progress has been made in transplantation techniques. Corneal transplants enhance vision for patients with damaged corneas; however, treating the retina remains challenging due to its connection to the central nervous system.

In 2023, a partial face transplant and a full eye transplant were performed, but vision restoration was not achieved—a significant hurdle. The retina is vulnerable to degeneration due to oxygen deprivation, known as ischemia. Johnson explains, “Even brief periods of ischemia may cause permanent damage to light-sensitive neurons and circuits.”

Eimear Byrne from Barcelona University of Science and Technology led researchers who aimed to mitigate this damage by replicating the conditions donor eyes encounter in the body.

They developed a system that channels blood through a flexible tube into the ophthalmic artery, nourishing the eye and surrounding tissues. The Eyes-in-Care-Box utilizes sensors to deliver oxygenated solution, ensuring optimal pressure and flow.

The researchers tested their technique on six donors, where one eye was perfused, while the other was not. Results indicated that the perfused eyes maintained retinal structure and cellular health for up to 24 hours, contrasted with rapid deterioration in the non-perfused eyes.

After perfusing 36 additional eyes, they found that 15 exhibited electrical light responses akin to those in living humans—lasting up to 10 hours post-mortem, double the previous average of five hours. Although other scientists made similar discoveries in 2022, the reasons for the limited response in 21 eyes remain unclear.

A significant challenge persists: regenerating the severed fibers of the optic nerve to connect with the brain’s visual center. Johnson highlights, “Without this regeneration, the donor eye cannot relay vision to the recipient’s brain.”

While this new research does not resolve that issue, maintaining healthy eye metabolism after death may facilitate future strategies for vision restoration and enhance donor eyes’ resilience to ischemic damage.

Many organizations are investigating potential interventions to promote optic nerve regrowth. “Now is the perfect time to integrate these promising strategies for whole-eye transplantation,” Johnson expresses.

Byrne’s team suggests the Eyes-in-Care box could also allow for testing vision-related treatments on human eyes instead of alternative animal models. “This technology has significant potential for advancing the understanding of biology and pathology, as well as developing new in vitro models for testing drugs and other treatments,” Johnson asserts. “These results will be directly applicable to human diseases and biology.”