Completely blind mice can now see after getting special injections in an experiment by scientists.
Cells that can sense light were injected into the rodents' eyes by a team in Oxford, England.
After two weeks, the injections had helped to rebuild the eye's retina - a layer at the back of the eye that converts light into something you can 'see'.
It's thought this finding could help humans who have lost their sight.
Professor Robert MacLaren from the study said it was like "restoring a whole computer screen".
But there are still questions over how good the quality of restored vision is.