Corneas are composed of several layers of different tissues. The predominant layer is composed of regularly arranged, highly hydrated collagen fibers with embedded keratocyte cells. Cornea transplants are frequently performed to cure certain eye diseases, but require freshly procured corneas from donor cadavers, which are in short supply. Moreover, they are susceptible to infection, rejection, and other implantation problems. Researchers under Dr. Curtis W. Frank at Stanford University have recently developed a hydrogel polymer composite that they hope to use to produce a viable synthetic cornea implant. The material, called Duoptix™, is comprised of two polymers. The first, Polyethylene glycol, protects the material from protein adhesion and inflammation of surrounding biological tissue. Polyacrylic acid is the second polymer and aids in the hydration of the material. Like biological hydrogels, Duoptix™ has a stable water content of ~80%. Besides being durable, strong, elastic, transparent, and permeable to nutrients (properties required of corneas), Duoptix™ corneas also contain microscopic pores that allow for the entry of native host keratocytes. Once implanted, these cells will enter the pores. Inside the material, they facilitate integration with native tissue and synthesize collagen like that found in natural corneas. These cells also aid the long-term maintenance of the new cornea. Tests on animals have confirmed that Duoptix™ based corneal implants are biocompatible and successfully replicate the activity of natural corneal implants.
Donor corneas are in short supply because they must be removed from a cadaver by a trained surgeon within hours of death and stored properly. Moreover, since LASIK surgery rates are increasing worldwide (which disqualify corneas for donation), the supply may be decreasing. Synthetic corneas based on Duoptix™ would be immunologically inert and relatively cheap to procure. Moreover, they would likely cause an increase in the rate of visual recovery in implant recipients due to their more predictable shape.
Over 10 million people worldwide are blind due to cornea related diseases. The supply and compatibility of donor corneas is simply insufficient to satisfy the large quantity that is in demand.Edit Summary