Ever Wondered how eye floaters work?

You walk out of the house on a bright day and clear blue skies, but suddenly you see little transparent worm or blobs floating in your field of vision. If you try concentrating on these, they suddenly seem to disappear but when you shift glance it's right back in front of your eyes. Have you ever wondered why this happens?

This phenomenon is known as eye floaters. The scientific term for this is "Muscae Volitantes". What you see aren't actually bugs or any external objects. Rather they exist inside the eyeball. The movement of these floaters might make it seem like it's alive but it's not. If you are familiar with the structure of our eyes, then you might be familiar with vitreous humor. Vitreous humor is a gel-like substance that fills the cavity of the eyeball between the lens and the retina. Tiny objects that such as bits of tissue, red blood cells or clumps of protein float in this vitreous humor tend to cast a shadow on the retina. This shadow is what is seen as these floaters. These floaters move with the movement of the eye, which is why they seem to be alive. The floaters will be more distinguishable and visible the closer it is to the retina, just like how shadows are darker when you are closer to the light source.

You might have also noticed that you tend to see floaters more often when you are under brighter conditions. Floaters are particularly more noticeable when under a consistent backdrop such as a white screen or clear blue skies. The brighter the light is, the more your pupil contracts and mores the focus on the floaters. 

There is another phenomenon that is similar to floaters that could be causing this. Blue field entoptic phenomenon is where dots of light darting about when looking at a bright blue sky. This sensation is not caused by shadows but by white blood cells. White blood cells can be so large that when they move along capillaries along the retina they slow down red blood cells following behind. This creates a plasma space to open up. This pile-up of red blood cells prevents light from passing through them, whereas light can pass through the plasma spaces and the white blood cells. Where ever this happens, a moving spot of light is observed. Sometimes a black tail also might visible, which is the red blood cell part. 

When these phenomena happen very mildly our brain tends to ignore them. Only when the floaters are in large number of large sizes is when we notice it. 

So next time you catch the floaters, remember that scrubbing your eyes is not going to shoo them away;)