Like Mr Draper I suffer from 'visual disturbances'. Fortunately, do not get any headaches associated with them. After reading the link posted by Turin, I conclude that these are Occular migraines.
The boring attacks are just like grey clouds that obscure the vision, can be frightening if they come on whilst driving.
They can, however, be quite spectacular at times, like looking into a kalaidescope, full of jagged patterns that swirl and move. Who needs mind enhancing drugs, this comes free!