Ageing is a degenerative process that leads to tissue dysfunction and death. At a molecular level, disruption to patterns of gene expression caused by the accumulation of epigenetic ‘noise’ has been suggested as a potential mechanism for the decline in tissue function. In this week’s issue, David Sinclair and his colleagues report that expression of three Yamanaka transcription factors in ganglion retina cells reprograms them to a more youthful epigenetic state and turns back the clock for nerve cells in the eye. The researchers found that the transcription factors restored youthful DNA methylation patterns and transcriptomes in the tissue. As a result, mice with damaged optic nerves were able to regrow axons, and vision loss was reversed in a mouse model of glaucoma and in old mice. The team found that enzymes that remove DNA methylation were required to repair eyesight. These results show that mammalian tissues retain a record of youthful information, encoded in part by DNA methylation, which can be accessed to improve tissue function and potentially to reverse the effects of ageing.