Floating Away: What exactly are those things in your eyes?

We have all done it at some time or another, either on purpose as kids or inadvertently as adults. You firmly press down on your closed eyes and then open them and immediately look at a bright light. Suddenly your scope of vision is turned into a veritable petri dish as dozens of little floaty amoebas dance in your periphery. You try to focus in on the little transparent blobs but they clear away, only to reappear as soon as you stop trying to catch them. In the eye care world, these amoebas are known as floaters, but what exactly ARE they? 

Floaters are a visual phenomenon known as “muscle volitantes” which translates to “flying flies.” As their name suggests floaters, like flies, can be highly annoying. However, these two traits are about the only things they share with the insect world. In fact, floaters aren’t external objects at all as they exist inside your eyeball, and although floaters change shape and appear to move on their own, they are not alive. They are tiny objects that cast shadows on the eye’s retina. They can be bits of tissue or protein or even red blood cells, and they float suspended in the gel-like liquid inside the eye. Because they drift along with your eye movements, they appear to be able to move on their own. Floaters are barely distinguishable most of the time, but as they drift closer to the retina, they become more visible. They also appear more in focus when you are looking at a uniformly bright surface because the even background makes them easier to make out. 

Similar to floaters are the tiny dots of light you might see when looking at a bright blue sky. These lights are known as “Blue Field Entopic Phenomenon” and they are actually the opposite of floaters. They are not shadows but little moving windows letting light through to the retina caused by white blood cells moving through the capillaries along the retina’s surface. The white blood cells are more transparent to blue light than the red blood cells or the capillaries themselves, so we see a moving dot of light whenever we look at a brightly lit blue background. 

Most of the time, floaters and other visual phenomena are harmless and the brain is able to ignore them. If the floaters are abnormally large or plentiful, however, they could be a sign of a more serious condition and an eye care specialist should be consulted. If you think your eyes contain an excess of floaters, please contact Dr. Vu and her friendly staff and we will make sure your vision is restored to its clearest potential.

Tim Cruz