There are things we see that are almost impossible to reproduce on canvas, or digitally. Things like the patterns behind our eyelids that propagate geometrically when you press on your eyes, or the beautiful prismatic chromatic aberrations from sunlight through your eyelashes as you hold them open ever so slightly. Here are samples from a series of images I’ve been creating called “Eyes Half Closed.” These were created in Photoshop, using photos which I took through polarized mylar sheets and glass marbles. I added things like “floaters,” trying to reproduce the loose blood cells we observe floating inside our eyes. I’ve got quite a few of these which I want to make into an interactive looping slideshow to soothing music. (click to view full size.)
Meinert Hansen 
I’ve always been facinated by this effect. Esspecially the colors and bokeh it produces. So glad I am not the only weirdo who thinks of this stuff :D.
Beautiful project, Meinert!
Indeed, you are not alone. I too am coming out of the closet with my previously unrevealed interest in this subject. The inner nerd in me theorizes that these effects are physiologically produced through a combination of the following processes:
1) Circles of confusion resulting from light passing through spaces between eyelashes which each act like the aperture of camera obscure, much like the spaces between leaves in a tree acting as multiple apertures, and projecting circles of confusion of sunlight on a wall or a sidewalk if conditions are just right.
2) Diffraction effects, with the eyelashes acting as a diffraction grating.
3) Floaters (deposits in the vitreous humour of the eyeball that cast shadows on the retina).
4) Refraction effects from the precorneal film layer being uneven due to squinting and therefore producing irregularities as different wavelengths of light pass through it.
Just guesses, except for the floaters.
Frank, you’re amazing! These are wonderful astute descriptions, and far from guesswork in my opinion. Our eyes behave so similarly to cameras sometimes. It’s the aqueous nature of our physiology that adds an extra effect that cameras don’t quite capture. Thanks for your comments!