Can Newts Regenerate Their Eyes?
Newts can regrow the lens of the eye. When researchers removed the whole lens from adult newts, a new one grew from cells in the upper part of the iris. A long study found Japanese newts regrew a working lens 18 times over 16 years. Sources we opened do not show that a newt can regrow an entire eyeball, so we do not claim that.
Newts are famous for regrowing body parts. The eye gets the most attention, because the lens is a clear, complex structure and humans cannot replace theirs.
The facts are narrower than the headlines. The strongest evidence is for the lens. Here is what the research says and where the limits are.
How this was made: prepared with AI assistance and checked against the sources listed at the end. Images are AI-generated illustrations, not photographs of real animals or products.
Key Takeaways
- Adult newts regrow a complete lens after it is removed.
- The new lens grows from pigment cells in the dorsal (upper) iris, not from old lens tissue.
- A University of Dayton study removed lenses 18 times over 16 years with no loss of quality.
- A 2015 eLife study of Japanese newts found regenerated lenses matched young lenses in gene activity.
- We found no source showing a whole eye regrows.
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What exactly grows back
In the lens experiments, scientists surgically removed the entire lens from adult newts. The animals then grew a new lens. An eLife paper on Japanese fire-bellied newts (Cynops pyrrhogaster) states that regeneration is possible after complete removal of the lens.
This is different from fixing a damaged lens. The old lens is gone, and the animal builds a new one from other tissue.
Where the new lens comes from
The new lens does not come from leftover lens cells. It grows from pigment epithelial cells in the dorsal iris, the upper part of the iris. The cells change type in a process called transdifferentiation.
An article in the International Journal of Developmental Biology notes that the lens regenerates from the dorsal but not from the ventral (lower) part of the iris.
The 16-year experiment
A team led by Panagiotis Tsonis at the University of Dayton, with Goro Eguchi, ran a study from 1994 to 2010. They removed the lenses of the same newts 18 times. The animals were believed to be at least 30 years old at the end.
The 17th and 18th regenerated lenses closely matched intact lenses from adult newts that had never regenerated, according to a University of Dayton report on the study published in Nature Communications in 2011.
Counts differ slightly between papers. The eLife follow-up describes 19 regenerations in one place and 18 removals in another, so treat “18 to 19 times” as the range.
| Study | Species | What it found |
|---|---|---|
| Nature Communications, 2011 (Eguchi, Tsonis and colleagues) | Japanese newts | 18 removals over 16 years; late lenses matched normal lenses |
| eLife, 2015 (Sousounis and colleagues) | Cynops pyrrhogaster | No significant gene differences between regenerated and control lenses; no cataracts |
What about the retina and the whole eye?
Researchers also study retina regeneration in newts, and the International Journal of Developmental Biology paper treats lens work as a simpler model for it. We could not open a source that gives a full, plain-language account of retina or whole-eye regrowth, so we leave out the details.
So the safe answer is yes for the lens, and the evidence is thinner or not shown in our sources for other eye parts.
Which newts do this?
The best long-term evidence comes from Japanese newts. Other newt species have been used in regeneration research, but the sources we opened for this post focus on Cynops. Where a single species is not named in an older article, we use Japanese fire-bellied newts as the example because the research is clearest for them.
Do not try to test regeneration at home. Hurting an animal for curiosity is cruel and, in many places, illegal.
Why this matters
The eLife authors say the regenerated lenses showed no cataracts and no age-related decline in the measured genes. That makes newts a useful model for studying ageing and tissue repair.
No newt study proves a treatment for people. Be cautious of claims that newt research will soon cure eye disease.
Frequently Asked Questions
Can newts regrow a lost lens?
Yes. Studies on Japanese newts show a complete lens regrows from the dorsal iris after removal.
How many times can a newt regrow its lens?
One long study removed the lens 18 times over 16 years, and the newt still regrew a normal lens.
Can a newt regrow a whole eye?
No source we opened shows this, so we do not say it does.
Can humans regrow a lens like a newt?
No. Human eyes do not do this, and research is still early.
Do newts regenerate other body parts?
Yes, newts are well known for regeneration. See our guide on [how newts reproduce](https://www.amphipedia.com/how-do-newts-reproduce/) for their basic biology.
Bottom Line
Newts can regrow a full lens from the upper iris, and they can do it many times without losing quality. That is a well-supported result.
For broader newt facts, see [how many types of newts there are](https://www.amphipedia.com/how-many-different-types-of-newts-are-there/) and [do newts have toxic skin](https://www.amphipedia.com/do-newts-have-toxic-skin/).
Sources
- eLife (2015): A robust transcriptional program in newts undergoing multiple events of lens regeneration throughout their lifespan, accessed Cynops pyrrhogaster, dorsal iris, no cataracts
- University of Dayton via Phys.org: Overturning a theory of age (2011), accessed 18 removals over 16 years
- International Journal of Developmental Biology: newt retina and lens regeneration, accessed Dorsal but not ventral iris
