Doctors transplanted artificial corneas made from pig collagen into the eyes of visually impaired patients, some of whom had eyesight so bad that they were legally blind. But two years following the surgery, all the patients saw dramatic improvements in vision, including three patients who now have 20/20 vision after being legally blind.

The Iranian and Indian patients all suffered from an eye disease called keratoconus, a condition in which the cornea (the clear, dome-shaped front surface of your eye) thins and gradually bulges outward into a cone shape. The disease affects up to 2 out of 1,000 people and often requires surgery to remove a full-thickness portion of the malfunctioned central cornea and replace it with donor tissue. But as you might imagine, there aren’t many cornea donors around, and only 1 out of every 70 people in need of one actually receive one.

If there are no donors, that means we’ll just have to make our own corneas, researchers at Linköping University in Sweden must have thought. They dissolved pig skin tissue to extract collagen, purified it, then used it to make a hydrogel that essentially mimics the human cornea. The hydrogel was inserted into pockets of the patient’s cornea to thicken it out and reshape it to restore the cornea’s function — and it worked.

Most of the patients improved their average visual acuity to 20/58 with glasses, meaning they need to be 20 feet away to see an object that people can normally see from 58 feet away. Not the best eyesight, but still light-years ahead of what they could see. Three of the patients even gained 20/20 vision, meaning they now have the clarity or sharpness of vision of a “normal” person, after they used to be legally blind (20/200 vision).

Two years after surgery, the patients still retained these improvements. And although their corneas now technically contain foreign biological material, because collagen is a structured protein that lacks individual cells, the patient’s immune system didn’t reject the implant.

“Fourteen of 14 initially blind subjects had a final mean best-corrected vision (spectacle or contact lens) of 20/36 and restored tolerance to contact lens wear. This work demonstrates restoration of vision using an approach that is potentially equally effective, safer, simpler, and more broadly available than donor cornea transplantation,” the authors wrote in their study.

Pig skin-sourced collagen is a byproduct of the food industry, and is thus broadly available and cheap. Although eye surgery sounds complicated and risky, the operation only took about 30 minutes per patient, whereas conventional cornea transplants from human donors can take a couple of hours. Doctors aren’t sure how much the surgery would end up costing, but what they’re certain of is that it should be more affordable than donor transplants, which can cost north of $25,000 in the U.S., depending on your insurance plan.

It’s not at all clear at the moment, however, if this procedure would work for patients who have other forms of corneal disease other than keratoconus. Some patients, for instance, have corneal scarring from bacterial or viral infections. Will it work for them too? These sorts of questions may be hopefully answered in the affirmative once the researchers receive approval for new trials. At the moment, they are focused on replicating the present results in a much larger sample of 100 patients.

The new findings appeared in the journal Nature Biotechnology.