Glenn: Thanks for your thoughts, on potential 'Visual Phantom Limb'.
In more detail, the term 'first derivative' comes to mind, perhaps only vaguely applies here:
Sweeping the hand, with eyes closed, you have to, first, realize the nature of the 'appearance' of your visual field, like in a darkroom. Many folks experience a slightly granular and mottled field, looking like a close-up magnification of human skin.
Actually, as an aside, MY latent visual field has taken a decidedly 'Polka-Dot' resemblance, (since started on typical blood pressure MEDS, a decade or so ago).
With a minor amount of searching, I haven't found any medical / neurologist research on this exact topic, (latent visual static field, aside from visual 'noise'.)
I suspect, that much of the bulk of literature involves descriptions and texts relating YOGA practices, in older cultures of INDIA and nearby.
(I like Chi-Gung, loosely termed as a Moving Yoga.)
That (cultural) history is not fiction:. Many stories exist, relating 'great visions' and sense of 'future' events. Any 'clinical' criteria seeks to confirm a lack of psychosis or other blatant mental illness, I don't know much about that angle.
But anyway, back to my observation:
It's as if there is a 'mottled' visual image, perhaps that's bundles of neurons, (also in v cortex): and this pattern, grainy pattern is 'disturbed' kind of like if it was a some loose feathers, sitting on a flat surface, and your 'hand' waving across those loose feathers causes some to shift, a little. After the 'hand sweep' it doesn't really look any different, (loose fluffy feathers),
but it just seems like some parts shifted, some places slightly darkened, after hand passes over.
So it's subtle.
For the 'mental illness' factors, that's beyond my expertise, but consider, for a second, VAN GOGH, with the swirling patterns in some of his art. THAT, there looks more like poison or other massive toxic, some have said he 'tasted the paint'.
I, I don't know, about that.
But, Visual Phantom Limb might be due to the literally billions of hand movements we use, there in front and center, inches from eyes.