Eye Drive
From Tardis Wiki, the free Doctor Who reference
The Eye Drive is a device created by The Silence to allow selected individuals to remember them when they are not present. The device forms a neural link with the user's mind and continually reminds them of The Silence existence. Despite its appearance, it does not inhibit vision out of the covered eye.
The Silence built a fail-safe into the devices that causes pain or death when activated, depending on the individual. This fail-safe is integral to the functioning of the device; any duplicates include it.
