Methods and apparatus for representing user output data by transcutaneous stimulation of a user's optic nerve

An apparatus comprising:

• at least one processor;
• memory storing a program of instructions;
• wherein the program of instructions is configured to, with the at least one processor, cause the apparatus to perform actions comprising at least:
• generating user output data;
• converting the user output data to representations corresponding to light signals;
• and
• performing control functions to at least two current sources to cause generation of electrical outputs in the form of at least a balanced differential signal which, when applied to the skin of a user, stimulate an optic nerve of the user so as to cause the user to perceive the light signals.

A non-transitory computer readable medium storing a program of instructions, execution of which by a processor configures an apparatus to perform actions comprising at least:

• generating user output data;
• converting the user output data to representations corresponding to light signals;
• and
• performing control functions to at least two current sources to cause generation of electrical outputs in the form of at least a balanced differential signal which, when applied to the skin of a user, stimulate an optic nerve of the user so as to cause the user to perceive the light signals.