Scientists have learned how to make eyes grow on a tadpole's back and head. They did so by manipulating cell membranes in those areas. Says study author Vaibhav Pai,
The hypothesis is that for every structure in the body there is a specific membrane voltage range that drives organogenesis. These were cells in regions that were never thought to be able to form eyes. This suggests that cells from anywhere in the body can be driven to form an eye.
Yes, pretty soon we will be able to have eyes anywhere we want. This will no doubt lead to moms requesting eyes in the backs of their heads, and hopefully to at least one person getting eyes in his hands like the scary guy from Pan's Labyrinth.