A blind man has received the gift of sight, thanks to an innovative stem-cell treatment. The treatment, which was part of a trial examining the safety of using human embryonic stem cells (hESCs), has restored the man's vision enough for him to pass any standard vision test for a driver's license.

"There's a guy walking around who was blind, but now can see," said Gary Rabin of Advance Cell Technology (ACT). "With that sort of vision, you can get a driver's license."

This news comes on the heels of the announcement last week that U.S. scientists have successfully cloned human embryos to make stem cells, a development that has reignited the debate surrounding human cloning and the morality of experimentation with stem-cells.

The man was part of a trial that began in 2011 and involved 22 patients with either age-related macular degeneration or Stargardt's macular dystrophy. Age-related macular degeneration (AMD) is the leading cause of vision loss in people age 50 or older. The disease destroys the part of the eye that provides sharp, central vision. Stargardt's macular dystrophy, or Stargardt disease, is usually inherited and destroys the same part of the eye as AMD. Stargardt's, however, occurs in younger individuals.

ACT would not disclose which of the diseases the successful participant has. In January 2012, The Scientist reported that participants in this same study experienced only modest improvements in their vision during the first few months of the trial. But based on ACT's own reports, this participant has made enormous progress, with his vision improving from 20/400 to 20/40.

The primary goal of the trial was to see if stem cells are safe to use in this context. With these new developments, though, their focus may have shifted. And even with the miraculous success of this single participant, the company warns that this participant's progress may not be indicative of future results in the clinical trials.

"We continue to be encouraged by the progress we see in our ongoing clinical investigations, though the results included in the article were confidential and not intended for publication at that time," said Rabin. "Our plan is still to publish additional results from the clinical investigations when we have a significant aggregation of data."