• About 4,000 cornea transplants are carried out each year in the UK alone
• More than 1.5million new cases of corneal blindness are reported every year worldwide.
Millions could be saved from going blind or needing eye surgery thanks to a sight-saving glue.
The adhesive gel, developed by scientists, contains chemicals that when exposed to the light, seal cuts on the eye's surface.
Researchers hope the glue, which would come in an eye drop, could stop the need for so many corneal transplants. There is a worrying shortage of donors.
The cornea is a thin piece of tissue that can be easily damaged by injury or infection, sometimes by contact lenses or a fingernail.
The developers of the glue, at Harvard Medical School in Boston, hope to start human trials within a year.
About 4,000 cornea transplants are carried out each year in the UK alone, and around 117,000 in the US.
Study author Professor Reza Dana said: 'Our hope is this biomaterial could fill in a major gap in technology available to treat corneal injuries.'
In the lab, the glue worked within days to replicate the eye's surface.
As well as helping wounds to close, the substance - named GelCORE - also fuels the growth of new tissue.
Professor Dana said: 'We set out to create a material that is clear, strongly adhesive, and permits the cornea to not only close the defect, but also to regenerate.
'We wanted this material to allow the cells of the cornea to mesh with the adhesive and to regenerate over time to mimic something as close to the native cornea as possible.'
An eye infection or trauma on the surface of the eye can cause scarring - leading to blurring or complete vision loss.
More than 1.5million new cases of corneal blindness are reported every year worldwide.
The current standard treatments for corneal defects include synthetic glues as well as surgery.
But these are rough, toxic, difficult to handle and can lead to significant vision loss due to the material's opacity and poor integration with corneal tissues.
Corneal transplants also carry risks of post-transplant complications, including infection or rejection.
The developers of GelCORE, described in the journal Science Advances, believe this opens a door to an unmet clinical need.
It is made of chemically modified gelatin and molecules called 'photoinitiators' that are activated by blue light found in sunlight.
The function of the cornea is to focus light. Initially, the glue is clear and liquid, but when exposed to light the material hardens to take on the natural structure of a cornea.
Over time, the cornea cells gradually grow into the material, bond with it and regenerate tissue.
GelCORE is the first adhesive gel - some have been made for the lung and other eye defects - to use visible blue light instead of ultraviolet light.
Unlike UV rays, blue light, which is also found in smartphones, does not cause cancer.
The properties of GelCORE can also be finely controlled by varying the concentration and the amount of time exposed to light, said the researchers.
This offers the possibility of changing the formulation for different types and severities of eye injuries.
Professor Dana said: 'We envision, if a patient comes in with a big laceration, they might receive formulation A.
'If they come in with a corneal scar, they might get formulation B.'