If the results can be translated into a treatment for human eye disease, it could help millions of people suffering with conditions ranging from age-related macular degeneration to diabetes. In U.K., a team of scientists took cells from three to five-day old mice, a stage when the retina is about to be formed. The cells were then transplanted into animals, which had been genetically designed to have conditions, which meant they would gradually lose their sight - either mimicking the human disease retinitis pigmentosa or age-related macular degeneration. The transplants were successful; the photoreceptors implanted and made electrical connections to the animals' existing retinal nerve cells. That is the key to regain vision. Tests showed that the mice's pupils responded to light and that there was activity in the optical nerve, showing signals were being sent to the brain. They were able to help them see again by transplanting immature retinal stem cells into their eyes. The research holds the potential to reinstate vision even in those who have already lost those crucial cells, scientists said.The study is funded by the Medical Research Council. The team included scientists from the University College London Institutes of Ophthalmology and Child Health andMoorfields Eye Hospital.