An example of the sort of work presently taking place aimed at retinal regeneration:
The researchers worked with mice that are blind due to complete loss of the light-sensing photoreceptor cells in their retinas. This is the most relevant mouse model for treating patients who are blind from retinitis pigmentosa. After two weeks, the researchers showed the cells transplanted into the eye had re-formed a full light-detecting layer on the retina and the mice could see. The cells used were mouse 'precursor' cells that are on an initial path towards developing into retinal cells.
A pupil constriction test showed that, of the 12 mice that received the cell transplant, 10 showed improved pupil constriction in response to light. This shows that the retinas of the mice were sensing the light once more, and this was being transmitted down the optic nerve to the brain.
"We found that if enough cells are transplanted together, they not only become light sensing but they also regenerate the connections required for meaningful vision. Stem cells have been trialled in patients to replace the pigmented lining of the retina, but this new research shows that the light-sensing layer might also be replaced in a similar way. The light-sensing cells have a highly complex structure and we observed that they can resume function as a layer and restore connections after transplantation into the completely blind retina."