Why You Get Squiggly Shit in Your Vision
Your eyes are immensely intricate machines built through millions of years of evolution, so it's only reasonable that they should have developed a few glitches along the way. For instance, the dots or squiggly lines that are sometimes visible off to the sides of your visual field. They float around and then dart out of sight immediately if you try to get a good look at the bastards.
These damn things.
And then you have the bright spots that appear in front of your eyes ("seeing stars") when your body suddenly strains really hard. Maybe you sneezed, or pulled an intense, full-body Valsalva maneuver trying to squeeze out a dissident turd, or just rubbed your eyeball.
Both phenomena are completely normal, yet the explanations are weirder than you think.
It Happens Because ...
First of all, "eye floaters" are not a) just lint and shit that fell into your eye or b) unusually upstart sperm that got really really lost.
Your eyes are mostly made up of a jelly called vitreous fluid, and this gel undergoes many changes as you age. As it slowly shrinks, it loses its smoothness and starts to look stringy. The vitreous can also become more liquid, and this allows for tiny fibers in your eye to come together and form (relatively) large clumps. These get big enough to become visible and freak us out, but they eventually sink down and settle at the bottom of your eyes where you can't see them. So technically, they're your little buddies for life.
Everyone you love will die, leaving ocular degeneration your only friend.
As for the bright dots that flash and move in front of your eyes, they're called phosphenes, and they're caused when cells in your retina are messed with (by rubbing your eyes or having a large person slap you in the dark), causing them to misfire. Strangely, scientists have found that they can also stimulate phosphenes by running electricity across the visual cortex part of your brain. Try it on a friend!