Collagen for cornea

Here is good news for those awaiting a corneal transplant: Researchers from Sweden, Iran and India have successfully developed and tested an artificial cornea made of collagen.

Loss of corneal transparency and poor refractive function are among the leading causes of blindness worldwide. Although corneal blindness can be treated by transplantation, an estimated 12.7 million people await donor cornea, with one cornea available for every 70 in need. Every year, 1 million cases are added to this waitlist.

The scene, however, could improve drastically now that researchers, led by Neil Lagali of the Department of Biomedical and Clinical Sciences, Linkoping University, Sweden, have developed an artificial implant from collagen extracted from pigs.

Clinical studies carried out at the All India Institute of Medical Sciences, New Delhi, and a medical college hospital in Tehran, Iran, found it to be very effective.

"It is the first time an alternative to donor tissue has been used… The surgical method we developed appears to be simpler, faster and safer than standard corneal transplantation," Lagali told Shaastra on email from Sweden.

The feasibility studies carried out in India and Iran threw up exciting results. "Nineteen of 20 patients experienced significant gains in vision after the operation, and 14 blind patients regained their sight," he said. Three people had regained perfect 20/20 vision.

According to Lagali, the implant is more suitable for those suffering from diseases such as advanced keratoconus, where the cornea bulges out like a cone. Such patients often need to wear contact lenses following a transplant, but many cannot do so because of pain and discomfort, he said. "But after the operation all patients could wear contact lenses without any discomfort," Lagali said.

Unlike donor tissue, which must be handled only in approved facilities and be used within two weeks, the implant can be shipped around the world at room temperatures and stored for up to two years in a standard refrigerator, he said.

For making the implant, the scientists used collagen, the main structural protein found in connective tissues, extracted from pigs. The collagen is so purified that it contains no cells, DNA, or other biological material. They exposed the collagen to a chemical process and ultraviolet light to strengthen and sterilise it further.

"Because of this, there is almost no chance of the body rejecting it. This is why only eight weeks of medication are needed post-operatively," he said. Donor tissue, on the other hand, contains cells and other biological material and can pose a rejection risk. Patients need to take medications for a year or longer.

The team, which included Namrata Sharma, an ophthalmologist from AIIMS, will now conduct larger clinical trials. "If we get good results, we will apply for approvals to market this implant," Lagali said.