Scientists have 3D printed the thin protective film over the eye, the so-called cornea, with human cells – and this is the most advanced version of an artificial cornea. If the technology improves, it could help millions of people to see each other again.
It was difficult to find the right recipe for an ink that was thin enough to spray through the nozzle of a 3D printer, says Che Connon, Tissue Engineer at Newcastle University, one of the creators of the artificial cornea was. Not only did this Biotinte have to be thin, it had to be so stiff that it could retain its shape as a 3D structure. To get the right consistency, researchers added a jelly-like goo called alginate and stem cells from donor corneas, along with some sticky proteins called collagen.
The cornea is the first lens that passes light before it finally hits the retina on the back of the eye. Damage to the cornea – injury or infection – can impair vision or even blindness. At the moment, the damaged corneas are being replaced by healthy ones from deceased donors, but there are not enough donated corneas to walk around. According to the World Health Organization, nearly 5 million people around the world are blinded because their cornea has turned sour.
The new technique described today in the journal Experimental Eye Research does not necessarily eliminate the need for corneal donation – these are the keys to include the stem cell in the recipe. But with this technology, the donation goes much further, says Connon. Instead of replacing a damaged cornea with a healthy cornea, you could grow enough cells from a donated cornea to print 50 artificial ones.
To find out what exactly was to print, the team had to find out the shape of a human cornea. So the researcher used a special camera to display a volunteer's eyeball and create a 3D model of his cornea. Then the team fed this template to a 3D printer, which injected the biotin into a supporting bed of Jello to create the cornea. The result looks like a soft contact lens in a bath of goo.
But still, it's a long way to go before this artificial cornea comes close to a human eyeball: Connon first wants to fine-tune the printing process, he says, and the artificial cornea also needs to undergo safety studies. But this study is proof that you can make 3D printing that looks like a cornea and mostly contains the same ingredients. It is also the first time that researchers have recreated the characteristic curved shape of the cornea. Connon says this is the key to working the artificial cornea: "Without the shape you have no cornea – you have something else."