Summary in Seconds: overview the functions of the human cornea, and its disorders, like keratoconus. With the high demand for corneal implants, can bioengineered corneal implants save the day.
The cornea is the clear front portion of the eye that covers the iris, pupil, and anterior chamber. Its transparency enables light to enter the eye, while its curve bends the light, providing around two-thirds of the eye’s optical power. A normal healthy cornea lacks blood vessels because transparency is crucial for its function1.
According to the National Eye Institute2, corneal disorders primarily encompass Keratitis, dry eyes, corneal dystrophies, keratoconus, corneal abrasions, corneal ulcers, neovascularization, and foreign bodies. However, among the array of corneal disorders, “Keratoconus” stands out as the most frequent cause for corneal transplantation. It ranks as the most widespread corneal dystrophy, involving a progressive corneal thinning. This condition mostly impacts young adults, and usually affects both eyes.
Based on a survey encompassing over 95% of the world’s population, it was estimated that around 12.7 million people across the world suffer from blindness caused by corneal damage or disease. However, just one in every 70 patients actually receives a corneal transplant, with the majority of those requiring such transplants residing in low and middle-income countries. Unfortunately, access to effective treatment is severely limited in these regions3.
Researchers and entrepreneurs were able to create an alternative for human cornea, made primarily of the protein collagen. They used collagen molecules derived from pig skin, which had been purified and produced under stringent conditions for human use. This modern method has several benefits. On one hand, pigskin used for collagen extraction is a by-product of the food industry, making it accessible and economically advantageous. In addition, unlike donated corneas that have a shelf life of two weeks, these bioengineered corneas can be stored for up to two years before being used4.
In a recently published pilot study5, the bioengineered corneal implant was able to restore vision for 20 individuals afflicted with diseased corneas, many of whom were blind prior to receiving the implant. The study report indicated that the newly bioengineered corneal implant successfully treated advanced keratoconus. The report noted that the procedures were free from any complications; the tissue exhibited rapid healing, and a two-month regimen of immunosuppressive eye drops was enough to prevent implant rejection. In contrast, conventional corneal transplants typically require years of immunosuppressive medication use.
References
https://en.wikipedia.org/wiki/Cornea
2. Corneal Conditions, National Eye Institute. Last updated: August 3, 2019.
https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/corneal-conditions
3. Philippe Gain, et al., Corneal Transplantation and Eye Banking. JAMA Ophthalmic. 134 (2), 167-173 (2016).
4. Karin S. Leifler, Bioengineered Cornea Restore Sight to the Blind and Visually Impaired. Linkoping University News, October 6, 2022.
https://www.medicaldesignbriefs.com/component/content/article/mdb/insiders/mdb/stories/46787
5. M. Rafat, M. Jabbarvand, N. Sherma, et al., Bioengineered corneal tissue for minimally invasive vision restoration in advanced keratoconus in two clinical cohorts. Nature Biotechnology, published on line August 11, 2022.
https://liu.se/en/news-item/biokonstruerad-hornhinna-kan-ge-blinda-synen-ater