Bioengineered corneas: how close are we?

Bioengineered corneas are substitutes for human donor tissue that are designed to replace part or the full thickness of damaged or diseased corneas. They range from prosthetic devices that solely address replacement of the cornea's function to tissue-engineered hydrogels that allow some regeneration of the host tissue. In addition, there are also bioengineered lenticules that may be implanted into the cornea to improve vision by altering the refractive properties of the eye, an alternative procedure to refractive surgery. In recent years, there have been significant developments in many areas of bioengineered corneas, such as the clinical trials of an artificial cornea designed as a prosthesis, the development of completely natural corneal replacements, and the development of biosynthetic matrices that permit host tissue regeneration. For correction of refractive errors, a synthetic corneal onlay that allows stable overgrowth of epithelium appears to be promising.