An Eye for an Eye

By Dr. Ian Smith

It sounds like science fiction: scientists take cells from a damaged eye, grow them in a dish, put them back in place and restore a patient's eyesight. But this is fact, not fiction, and vision was restored not just to one person but to dozens of blind or nearly blind patients in Taiwan and the U.S.

The eye operations, reported by two separate research teams in last week's New England Journal of Medicine and the July issue of Cornea, represent the most dramatic successes to date of so-called stem-cell bioengineering--using the body's own master cells to make replacement tissue. Doctors have employed stem cells to grow skin grafts for burn victims and to repair cartilage in damaged knees, but the technique had never been used successfully in an organ as complex as the eye.

The patients treated had so severely damaged their corneas (the transparent layer that covers the iris) that conventional cornea transplants were no longer an option. Some 2,000 to 4,000 Americans suffer similar corneal scarring each year--from chemical burns, diseases or chronic inflammation, according to Dr. Ivan Schwab at the University of California at Davis, who led the U.S. team. The operation, however, cannot help those with congenital retinal or optic-nerve disorders.

The techniques used by the U.S. and Taiwanese groups were similar. Both took stem cells from the limbus, the circular area of the eye that surrounds the cornea. These cells were grown on a sterilized membrane for several weeks until they formed a layer five to 10 cells thick. Doctors then cut pieces to the size they needed and sewed them into place.

The results so far are good. The transplants improved the vision in 10 out of 14 American patients and in five of the six of the patients treated at Chan Gung Memorial Hospital in Taipei.

--By Dr. Ian Smith