When I close my eyes, I see just blackness, from the left of this blackness a greyish/whiteish line that runs from top to bottom, sweep across the blackness from left ro tight.

This has happended all my life and I don't know what it is or why it happens, I don't need to concentrate to make it happen, infact I can't stop it happening, I can't stop the line moving and I can't speed it up, all I can describe it like is a sweep of a radar line across a radar scope (not the round type)

Does anyone know what this could be?