My eigengrau is not completely uniform: there are subtle variations in monochrome intensity. If I concentrate on the eigengrau, interesting patterns can appear. I have some indirect conscious control over the patterns. For example, if I concentrate and ask for a red spot to appear, usually some shade of dim red will appear forming some pattern, but I don't have control over the details. I lost this ability some number of years ago, then practiced until I got it back.
I can only do this in perfect darkness with a lot of concentration, and I need practice to maintain and improve the ability. I think it's like this article titled "Direct Control of the Visual Field", where you teach yourself to control the Eigengrau: <https://zenodo.org/record/1429102>
The article on Visual Snow shows an actively animated noise field, and I don't see any animation unless I'm really in the groove. The Visual Snow article also implies that it causes distress, and that sufferers seek medical treatment to make it go away. That doesn't apply to me. I have never used hallucinogens, I've never had a migraine, etc. I consider myself creative, so that might be correlated.
For some reason I’m better at getting triangles to form.
I’m also the same as you- no migraines or anything that’d I’d consider a negative symptom.
The other optical-related illusion that someones happens with me is that if I’m focusing on something, occasionally everything else may ‘dim’ and that object will ‘feel’ subjectively closer/zoomed in, but a couple blinks and everything goes back to normal.
I’ll also add that I consider myself to have a terrible visual imagination. If I try and imagine a face (even my parents) I basically don’t get anything. If I concentrate very hard I can imagine something basic - like the wireframe of a cube - but requires a lot of effort to maintain.
To use your metaphor, my mental images are in an offscreen buffer. My eigenbrau is more like my on-screen buffer, but I can't see eigenbrau with my eyes open, presumably because then my eyes are using that channel.
I see wonky shit all the time, and have just put it down to individual differences in retina & processing sensitivity. But, I have the occasional migraine with aura, AND have used hallucinogens in the past.
So now I wonder how much my visual perception is caused by heredity, and how much by external influences...
There is also a disfunction of your cornea, "Fuchs' corneal dystrophy", which can cause glare, halos and streaks, especially at night. I just found this by googling.
Wikipedia defines visual snow as a neurological condition, and I don't wish to conflate that with floaters or corneal problems.
I can experience afterimages if I look at a strong coloured light for a while, then immediately look at a white piece of paper. I'll see an after image in the complementary colour, because the image is temporarily "burned in" to my photoreceptors. I understand that this is a universal experience.
What I'm looking for is different names for each of these distinct visual experiences, if they have different underlying mechanisms.
I always thought this is the way human see the world. But no it's just me and some other unfortunate people it seems. I too always assumed it's associated to migraines. Thanks for the visual snow hint!