Have you ever noticed something swimming in your field of vision.it may look like a tiny worm or a transparent blob,and whenever you try to get a closer look,it disappears.only to reappear as soon as you shift your glance.but don't rising out your eyes! What you seeing is a common phenomenon known as a floater.The scientific name for these objects is Muscae volitantes. and true to their name , that can be some what annoying.
But they are not actually bugs or any kind of external objects at all.Rather, they exist inside your eye ball. Floaters may seem to be alive, since they move and change shape,but they are not alive.Floaters are tiny objects that cast shadows on the retina,the light sensitive tissue at the back of your eye.They might be bits of tissue,red blood cells,or clums of protein.and because they are suspended within the vitreous humor, the gel- like liquid that fills the inside of your eye,floaters drift along with your eye movements, and seem to bounce a little when your eye stops
Floaters may be only barely distinguishable most of the time.They become more visible the closer they are to to the retina,just holding your hand closer to a table with an overhead light will result in a more sharply defined shadow. And floaters are particularly noticeable. when you are lokking form bright surface, like a blank computer screen,snow or a clear sky,where the consistency of the backgroundmakes them easier to distinguish. The brighter the light is, the more your pupil contracts.this has an effect similar to replace a large diffuse light fixture with a single overhead light bulb, which also makes the shadow appear clearer.
There is another visual phenomenon that looks similar to floaters but in fact unrelated.if you seen tiny dots of light darting about when looking at a bright blue sky, you have experienced what is known as the blue field entoptic phenomenon. In some ways this is the opposite of seeing floaters.here you are not seeing the shadows but little moving windows letting light through to your retina.the windows are actually caused by white blood cellsmoving through the capillaries along your retina's surface.