The human cornea is an amazing evolutionary component of the eye, which not only protects the eye against infection, but also refocuses light to greatly strengthen our visual capabilities.

Sadly though, the cornea is delicate and fallible to numerous chronic conditions, the most severe of which lead to blindness. Corneal blindness affects over 12 million people worldwide, but according to the SightLife organisation, over 80% of these cases are treatable.

So what is going wrong?

The problems with corneal transplantation

Corneal transplantation is a well-established treatment, but it can be severely limited in scope due to complex, sometimes risky surgery, a shortage of donors, and the long period of immuno-suppressive therapy following the operation.

This just isn’t feasible in many low-middle income countries, where the already high costs or treatment become exorbitant. However, bioengineers at Linköping University may have solved this issue.

Corneal transplants using pig collagen

The team of researchers developed a bioengineered corneal implant using a protein called collagen. For the clinical trial the protein was isolated from samples of pig skin, which were then highly purified and rigorously tested before human use.

Creating the implants in this way solves two major problems faced by transplantation. This source of collagen was chosen because pig skin is readily available and incredibly cheap, as it is a byproduct of the food industry. It can then be stored for close to two years before use. Human corneal tissue is only available through donation, and must be used within two weeks.

The researchers were also able to make improvements to the surgical procedure as well, by using assistive lasers to make precise incisions into the eye, so that the implant can be fitted without the need of invasive surgeries and stitches.

So we’ve reached the all-important question: how did the patients fare with this pragmatic approach to corneal care?

What were the results of the clinical trial?

The trial consisted of twenty patients suffering from Keratoconus (a condition of the cornea), and patients were monitored for two years after the operation. 14 of these subjects were blind before the operation.

All twenty of the patients saw improvements in their vision, and all 14 of the previously blind subjects regained the ability to see. At the two-year post-operation mark, there have been no rejections and all of the subjects have healthier vision.

According to the researchers, the visual acuity is equivalent to that of a human corneal transplant over the same duration, and may in fact exceed it once the five and ten year markers are reached, which are the most likely times for a transplanted cornea to fail.

So far, the success of this research is evident - and it does seem to be a viable and perhaps even preferential treatment. What is now required is a large, long-term clinical trial and data from those key 5-10 year markers we’ve mentioned.

The use of transplanted bio-materials from farmed animals is often treated controversially by certain groups and interest-bodies. While we don’t feel qualified to comment on this immensely complex debate, we do think that a clinical trial with a success rate of 100% is incredible. The fact that the technology used seeks to bring treatment of some forms of severe blindness into genuine affordability for all is also a remarkable achievement, and we await future trials with high hopes and expectations.

Sources:

1. LIU.SE.
2. Ophthalmologytimes.
3. SightLife.

Rafat, M., Jabbarvand, M., Sharma, N. et al. Bioengineered corneal tissue for minimally invasive vision restoration in advanced keratoconus in two clinical cohorts. Nat Biotechnol (2022). https://doi.org/10.1038/s41587-022-01408-w