After removing damaged corneas, surgeons transplanted clear corneas from deceased donors to the eye surface and then grafted peripheral corneal segments which contained corneal epithelial stem cells into 43 eyes of 39 legally blind patients. There was marked improvement in 51 percent of the patients. The cornea is the transparent window on the surface of the eye through which light passes. These cells on the surface are constantly turning over, just like the outer layers of the skin.
Stem cells are immature progenitor cells that can grow into mature tissue.
Stem cells for the corneal epithelium are located at the periphery of the cornea. The Japanese study found that 35 percent of the corneas became completely clear, and that the patients had visual acuity restored to a level that allowed them to perform daily activities. All patients gained enough visual acuity to become more self-sufficient. An expert on ocular surface disease, Gipson said that the study uses techniques that have been available for about a decade. The Japan group treated patients who had severe damage to the eye surface either through chemical or thermal injuries, or through conditions such as Stevens-Johnson syndrome or ocular pemphigoid in which conventional corneal transplants would not restore sight.