Perfused human retinas retain light-evoked electrical activity up to 10 hours after donor death

The team obtained donor eyes within hours of death, cannulated the central retinal artery, and delivered a controlled perfusate containing oxygenated hemoglobin and nutrients while maintaining physiological temperature and pressure. Multi-electrode arrays positioned on the ganglion-cell layer captured spiking responses to full-field flashes and patterned stimuli, confirming that photoreceptors, bipolar cells, and ganglion cells continued to transmit signals. This design directly measured functional output rather than relying on metabolic proxies or histology alone.

The 10-hour mark exceeds typical organ-preservation limits and challenges assumptions that irreversible ischemic damage occurs within minutes in neural tissue. Because the retina is an accessible extension of the central nervous system, the result supplies a concrete benchmark for how long certain circuits can tolerate anoxia when reperfusion is prompt and controlled. It also highlights that cell-type-specific resilience varies, with photoreceptors showing earlier decay than inner retinal neurons under the same conditions.

For whole-eye transplantation, sustained retinal signaling is necessary but not sufficient; optic-nerve regeneration, vascular integration, and immunosuppression remain rate-limiting. The current preparation nonetheless provides an ex-vivo assay to test candidate preservation solutions and to quantify the marginal benefit of additional interventions such as mitochondrial protectants or controlled reperfusion pressure ramps. Next steps include scaling the perfusion protocol to en-bloc eye transplants in large-animal models with behavioral readouts of vision.

Key limitation: the study used retinas from donors with no known retinal disease and short postmortem intervals before enucleation; results may not generalize to eyes from older donors or those with prolonged warm ischemia.