This collagen-based, bioengineered cornea is made from pig skin. Credits: Thor Balkhed / Linköping University
How Important are Corneas for Eye Health?
The cornea is a tough, transparent tissue that acts as a barrier protecting the structures inside the eye and against infections. Compared to other parts of the eye, the cornea does not rely on blood vessels; it takes in oxygen through its environment instead.
Healthy corneas promote good eye health. Severe damage from diseases or injuries can impair someone’s vision or at worst, leave them blind. Unfortunately, this is the reality for over 12.7 million across the globe who suffer from corneal blindness, one of the world’s leading causes of avoidable blindness.
In the Philippines, corneal blindness is among the top 5 causes of visual disabilities and blindness according to the Eye Bank Foundation of the Philippines.
Mild corneal damage can heal on their own, but some people need to get a transplant called corneal graft to restore their vision. This operation is expensive, invasive, and time-consuming. After the procedure, patients undergo medication for over a year to ensure their eyes won’t reject the implanted tissue.
Apart from the mentioned risks, doctors and hospitals face logistical challenges with human corneas. The donated tissue only lasts for 2 weeks within the donor’s death. Therefore, cornea transplants are rare, especially in poorer parts of the world like the Philippines.
A Future Cure?
Swedish researchers have bio-engineered corneal implants that have returned or improved the eyesight in 14 keratoconus patients. The small clinical trial involved 20 people undergoing corneal transplants, using bio-engineered corneas made from pig skin collagen.
Eye with keratoconus.
According to Linköping University Ophthalmologist Neil Legali, “it is possible to develop a biomaterial that meets all the criteria for being used as human implants, which can be mass-produced and stored up to two years and reach even more people with vision problems.”
Neil Lagali, professor at Linköping University. Credits: Thor Balked/Linköping University
Professor Lagali also stated that the implants will “get around” the problem of corneal tissue shortage, improving access to other eye disease treatments. “Collagen from pig skin is a byproduct from the food industry. This makes it broadly available and easier to get.”
The procedure involves making a tiny incision in the corneas of each patient and inserting the hydrogel cornea implant in the incision. This then helped thicken, reshape, the cornea, and fix the damage.
Compared to traditional cornea transplant operations, this hydrogel procedure is much faster, less invasive, and less expensive than the standard cornea transplant operations.
Standard cornea transplant operations involve cutting the eye open, removing damaged or diseased tissue, and replacing them with corneas from human donors. The procedure is invasive and removes “a lot of important cells and nerves in the cornea that are otherwise healthy,” Professor Lagali said.
Traditional cornea transplants can take a couple of hours, but this new procedure only took 30 minutes.
Just 8 weeks after the operation/clinical trial, the patients used immunosuppressive eye drops to lower immune reaction from the pig skin collagen. Unlike the several years of medication after the traditional surgery.
14 of the 20 patients regained some or all of their vision and could wear contact lenses again. Meanwhile, 3 of the 14 could achieve a 20/20 vision after the operation.
The patients tolerated the implants and did not experience inflammation, scarring, or any adverse side effects 2 years after the operation.
What Are the Doctors Saying?
Dr. Marian Macsai, a clinical professor of ophthalmology from the University of Chicago who was not involved in the study, stated in an NBC News interview with Aria Bendix that the new technology is a game changer for people with keratoconus.“The concept that we could have bio engineered corneas would be revolutionary,” she said.
Dr. Macsai added, “It might eliminate the risk of rejection and make corneas available to patients worldwide.”
Dr. Uri Soiberman from John Hopkins Medicine, who was also not part of the study, commented that the human body handles pig tissues “pretty well.”
However, Dr. Soiberman warned that any experimental medical procedure comes with risk and that the pilot study has limitations. The new technology is not useful for patients with scarring caused by viral or bacterial infections.
Future of the Breakthrough
Professor Lagali and his team are hoping to replicate the results on a larger study involving 100 or more patients. Following this, they aim to get regulatory approval from agencies like the Food and Drug Administration (FDA).
The research team’s goal with this breakthrough is to make the implants available to people around the world, especially in the countries where human cornea supplies are lacking.
“We really designed this material and technology and surgical procedure to be adopted in areas of the world where there are really low resources. Those are the same areas of the world where the burden of blindness because of this disease is the highest,” Professor Lagali said.
For more details about the research and the clinical trial, please click here.