The snail as a model for restoring vision in humans

In Hindu mythology, Lord Shiva’s third eye is said to open only in moments of great transformation. What if this isn’t just a mythic symbol of cosmic vision but also a metaphor for renewal?

Ever wondered if there’s a hidden switch that could unlock something just as extraordinary as the ability to regrow our own eyes? A camera-type eye, like that of humans and many other species, has a lens that focuses light onto a retina. Regeneration would be the ability of the eye to regrow itself after being completely removed or damaged. Recent work by Alice Accorsi and Alejandro Sánchez Alvarado’s team (Nature Communications 16, 2025) has shown how such regeneration of the eye occurs in a golden apple snail. The snail is a mollusc: a backboneless, shell-covered animal that can live equally well in land and water.

This miracle of regeneration isn’t magic but beautiful molecular choreography. When the snail loses an eye, thousands of genes flip like switches: first those guiding wound healing, then those for cell growth and division, followed by diverse networks for new retinal cells, photoreceptors, and lenses. Among them, the PAX6 gene plays a critical role in the early development of the eye. In snails, this process is carefully coordinated by several other genes. These include genes responsible for forming new nerve cells, guiding nerve fibres to their correct targets, and detecting light, each becoming active at the right stage to ensure proper development. We as humans can’t do the same yet but decoding these genetic triggers may one day help us awaken our own silent regenerative programs.

Just as snails can regrow their eyes, other animals such as frogs, planaria, and the African spiny mouse also possess strong regenerative powers. In axolotls, a type of salamander, damaged tissue can revert to a flexible stem cell-like state and rebuild bones, muscles, and other body parts. CRISPR is a gene-editing technology that enables us to redesign, remodel, and regenerate the genome structure we desire. At the L.V. Prasad Eye Institute at Hyderabad, scientists have used the CRISPR method to correct genetic eye diseases such as Leber congenital amaurosis (LCA) and Stargardt disease, using zebrafish as the animal model.

From animals to humans

Clinically, early trials have already targeted genetic disorders in humans — such as sickle cell disease; β-thalassemia, a birth-related blood deficiency disorder; and LCA, a type of congenital blindness — using CRISPR editing. Recently, a first-of-its-kind clinical trial outcome for the treatment of LCA in human patients using CRISPR technology has come from a team at Harvard University (N Engl J Med 2024;390:1972-1984), who showed improved vision in people with inherited blindness. These initiatives mark a shift from understanding regeneration in animal models to reactivating repair programs in human cells, establishing a framework for gene-guided regenerative medicine.

These examples remind us that regeneration isn’t a rare miracle. Instead it’s an ancient biological program still written into the DNA of many species, and one that science is gradually learning to decode and revive. The new study, on the golden apple snail, has revealed how its genome remembers to rebuild what seems irreparable, and in decoding that memory, science moves closer to restoring human vision: not through divine intervention but through molecular understanding.

The author is thankful to his colleagues Sonali Mohapatra and Dr Vivek Singh for their inputs.