The researchers are now testing the material for biocompatibility in animal models. Animals have tolerated artificial corneas with no problems in trials as long as eight weeks, Ta says. The material remains perfectly clear, he says. Longer trials are a next step.
The current source of tissue for corneal transplants is cadavers. Donor tissue has problems, Ta notes, including a rejection rate of about 20 percent and a period for visual recovery of six months to a year. "You get a more predictable shape with an artificial cornea," Ta says.
"In many countries, tissue availability is a problem," he says. "If the tissue is artificial, we don't have to rely on donor tissue." The high prevalence of laser-assisted in situ keratomileusis, or LASIK, eye surgery may contribute to the shortage of donor tissue in developed nations, he notes, as this surgery disqualifies donation. A tissue-engineered artificial cornea could lessen or eliminate the need for donor tissue.
At least a dozen groups worldwide are working to develop artificial corneas, Myung says. "Only two or three are on the market, but they are only used in last-ditch efforts [when transplants are rejected]," he notes. Stanford's artificial cornea is "the most biomimetic," he says, with a water concentration and mechanical properties that rival those of the natural cornea.
"The dream would be to have a corneal replacement that's sterilized and dehydrated and sent off to the hospital or battlefield, and rehydrated," Frank says.
Other ocular applications of the hydrogel include more comfortable contact lenses. Onlays of hydrogel lenses on the surface of the cornea could serve as extended-wear contact lenses.
Inlays are also