Jonny B
Youre seeing floaters, we all have them some more than others, the macular fluid in the eye over the years hardens and forms these tiny fibrous strands that look like all sorts of shapes.. its normal and you can expect to see more of them as you get older!

Fifa
It is cos of Phosphene production... "The most common phosphenes are pressure phosphenes, caused by rubbing the closed eyes. The pressure mechanically stimulates the cells of the retina. " Check the link for info :

reggieman
For the same reason I see spots arranged in Polygons.... You're pressing the liquid that presses against the nerves which fire off the receptors....the nerve bundles are arranged in a geometric pattern and you're firing off the MAIN substation where all the surrounding nerves send their messages to.... The smaller nerves are overwhelmed by the pressure, so you don't SEE the finer detail...you SEE the local substation message to your brain.....

toogethr
Any pressure on the eyeball - such as that produced when you rub your eyes, sends signals back to the retina. The retina of your eye is composed of millions of nerve endings (rods & cones) which are only able to transmit the signals to the brain. The brain interprets all these signals as "light". Rubbing the eyes produces many many signals together from your retina to your brain and since the brain can only interpret these as light thats why you see geometric patterns. Ever hear of someone getting punched in the face and seeing stars? Same thing happening.