Researchers at Moorfields Eye Hospital in London treated the patients as part of a clinical trial on patients who have lost their sight from chemical accidents or a rare genetic disease.
Using stem cells from tissue donors, surgeons grew the cells in the laboratory before transplanting them onto the patients' eyes.
Dr Julie Daniels, who is leading the research team, will present the results at a conference on regenerative medicine being held in Welwyn Garden City, Hertfordshire, today.
She said: "Before the surgery the patients were barely able to recognise when someone was waving a hand in front of their face but we have restored their vision to the point they can read three to four lines down the eye chart."
Nineteen patients have now received the treatment, known as limbal stem cell therapy, at Moorfields Eye Hospital.
The patients were chemical burn victims or sufferers of a rare genetic disease known as aniridia. They had injuries to the limbal cells in their eyes, which are under the eye lid and maintain the transparent layer on the outside of the cornea.
Dr Daniels said: "Their cornea becomes opaque, blood vessels grow across it and their eyes become inflamed and they can't see anymore. It is very painful.
"By replacing the limbal stem cells, the cornea begins to clear up as the cells are replaced with the healthy transparent layer again.
"We can't restore sight completely yet as the material we are growing the stem cells on is slightly opaque, but patients are certainly reporting an improvement."
Ten patients were given the transplant 32 months ago and six of those have showed remarkable recovery. The remaining nine patients were treated eight months ago and are still to have their recovery assessed.
Scientists at Moorfields Eye Hospital are also hoping to use stem cells to treat other causes of blindness by creating small patches of retina cells, which detect light at the back of the eye.
The Royal National Institute for the Blind (RNIB) welcomed the results of the limbal cell trial.
Barbara McLaughlin, campaigns manager at RNIB, said: "Anything that can restore sight to people who thought they had irretrievably lost their eyesight is a major step forward.
"This research is very exciting, but we would caution that these treatments can take a significant amount of time and research before they can be widely used."
More than 250,000 people suffer injuries to their eyes every year as a result of accidents, although only a small proportion of these are due to burns.