This snail can regrow its eyes — and may one day help humans do the same

The golden apple snail has camera-type eyes that are fundamentally similar to the human eye. Unlike humans, the snail can regenerate a missing or damaged eye. UC Davis biologist Alice Accorsi is studying how the snails accomplish this feat. This knowledge could help us understand eye damage in humans and even lead to new ways to heal or regenerate human eyes. (Image Credit: Alice Accorsi, UC Davis)

Imagine losing an eye and growing it back — lens, retina, optic nerve and all — within a month. It might sound like science fiction, but for the golden apple snail, it’s just biology. Now, scientists believe this humble freshwater snail could hold the key to regenerating human eyes.

In a fascinating new study published August 6 in Nature Communications, researchers at the University of California, Davis, reveal how apple snails can regrow fully functional eyes — and how their surprising similarity to human eyes could transform the future of vision restoration.

“Apple snails are an extraordinary organism,” said Dr. Alice Accorsi, assistant professor of molecular and cellular biology at UC Davis and lead author of the study. “They’re resilient, fast-breeding, and, most importantly, they can regenerate complex sensory organs like the eye.”

Eyes Like Ours — In a Snail
Using microscopy, dissections, and advanced genetic analysis, Accorsi’s team found that the snail’s camera-type eye — the same structure found in humans — shares striking anatomical and genetic features with our own. From a protective cornea to a light-focusing lens and a photoreceptor-packed retina, the apple snail eye mirrors ours in design.

What sets it apart? The ability to regrow the entire structure from scratch after injury.

“We showed that many genes involved in human eye development are also present in the apple snail,” Accorsi explained. “After regeneration, the new eye is virtually identical to the original — both in structure and gene expression.”

A Step-by-Step Guide to Regrowing an Eye
The eye regeneration process in apple snails is surprisingly efficient. Within 24 hours of losing an eye, the wound begins to heal. Then, undifferentiated cells swarm the site, multiply, and gradually form complex eye tissues.

By Day 15, all key components — even the optic nerve — are in place. Over the following weeks, these structures mature. Though scientists haven’t yet confirmed that the regenerated eyes can “see” in the way humans understand it, anatomically, they’re fully formed and ready to function.

Accorsi’s team tracked gene activity throughout the process. Immediately post-injury, around 9,000 genes were expressed differently than in normal eyes. Even after 28 days, over 1,100 genes were still behaving differently, suggesting that full functional maturity may take more time.

Genetic Editing: CRISPR and the Snail Genome
To understand which genes make this biological magic possible, Accorsi developed the first gene-editing tools for apple snails using CRISPR-Cas9. As a proof of concept, they disrupted a key gene known as pax6 — a master regulator of eye development in animals from flies to humans.

When both copies of pax6 were deactivated in snail embryos, the snails were born with no eyes at all, proving the gene’s crucial role. The next step? Mutating pax6 in adult snails to see if it's also responsible for regenerating eyes after injury.

“If pax6 and other regeneration genes are conserved in humans,” said Accorsi, “we could theoretically activate them to kickstart regenerative processes in people.”

Why Snails? Why Now?
Snails have long been known for regenerative abilities. In 1766, scientists reported that garden snails could regrow entire heads. But only now, thanks to Accorsi’s breakthrough methods, has a suitable model emerged for studying full eye regeneration.

Unlike other snails that are difficult to breed or undergo metamorphosis, golden apple snails are lab-friendly, fast-reproducing, and invasive — traits that, in this case, make them ideal for cutting-edge biomedical research.

Accorsi’s work, supported by the Howard Hughes Medical Institute and others, sets the stage for a future where severe eye injuries might not mean permanent blindness — but a window into regeneration.

“We’re still at the beginning,” Accorsi said. “But nature already has a blueprint. We just need to learn how to read it.”