Ottawa, Canada – Patients whose vision is impaired by a damaged cornea may soon have an alternative to a donor transplant to restore their vision. May Griffith of Linköping University in Sweden and Ottawa Hospital Research Institute has been working with colleagues to develop techniques for fabricating tissue replacements that can be used in place of natural donor tissue. Their most recent achievement is the successful testing of an artificial, biosynthetic cornea over the course of two years. Results with their synthetic cornea have proven to be as good or better than donor transplantation.
While more testing needs to be done on this artificial cornea and donor cornea transplantation is still the preferred treatment of corneal blindness, donor corneas are always scarce. Plastic corneas have been developed and used for years, but problematic side effects like infection and glaucoma have made them purely a last resort option.
This new corneal implant is special because it is made almost entirely from natural collagen, grown in vitro by corporate partner Fibrogen from yeast cells. This collagen was then molded into the shape of a cornea, mimicking the cornea’s stroma layer, which is mostly collagen.
All ten patients on whom the biosynthetic implants were tested had their vision restored to a level similar to corneal transplant patients, except that they needed contact lenses to smooth over bumps created by the implants. The team is currently testing alternatives to the sutures that cause those bumps, such as tissue adhesives. Results were also excellent in cell growth, with all ten patients seeing the return of the infection-fighting epithelial cell layer.
Washington – Scientists have developed a new type of artificial cornea by inserting a tiny amount of collagen into the eye in order to spur natural corneal cell regrowth. Initial reports indicate that the procedure has successfully restored vision in many of the trial patients.
The first wave of the study was conducted in Sweden. The sample size was very small – only 10 people. Therefore, additional studies evaluating a larger sample size will be required to conclusively determine the effectiveness of the procedure. If successful, this new artificial cornea may become a viable alternative to corneal transplants. In many parts of the world, there is a shortage of donated corneas, necessitating an alternative to meet this demand.
The cornea is a film-like covering of the eye’s surface that is responsible for focusing light on the retina. It is a fragile structure that is easily damaged by injury or infection. Approximately 42,000 people undergo corneal transplants in the United States each year. However, in many other countries, the demand for donor corneas far outweighs the supply.
Researchers are also working on several other alternative treatments such as plastic-like artificial corneas and stem cell treatments which may improve corneal growth. The current treatment being evaluated is considered a bioartificial cornea since it uses the same natural substances found in your cornea (collagen) to promote healing.
To create the bioartificial cornea, researchers molded human collagen grown in yeast into the shape of a contact lens in order to mimic the shape of a natural cornea. The damaged corneal tissue was then removed from patients’ eyes and the bioartificial cornea was implanted in its place. Corneal cells began growing in the collagen, tear production normalized, and corneal nerves began to regrow. None of the patients rejected the artificial cornea; rejection is a common risk with corneal transplants.
After two years, six of the ten patients experienced significantly improved vision with glasses and two patients experienced similar vision to before the procedure.
It is important to note that this technology currently only addresses upper layer corneal problems which comprise approximately 10% of corneal transplant cases. Moving forward, researchers will attempt to develop the technology to address full-thickness corneal damage which impacts the endothelial cells in the lower layer of the cornea.