Have you ever noticed a strange little worm-like speck drifting aimlessly about in your field of vision? These annoying little squiggly lines, or “cobwebs,” are called floaters and are experienced by around 70% of people. So what are they?

Floaters are actually shadows cast by objects suspended in the clear, gel-like substance that makes up the majority of the eye’s interior. This substance is called vitreous humor and helps to maintain the eye’s round shape. After passing through the lens, focused light has to pass through the vitreous humor in order to reach the retina at the back of the eye. It’s mostly composed of water but also contains proteins and various other substances.

Floaters are normally merely proteins of the vitreous gel that have clumped together. These stringy clusters of proteins block light and therefore cast a shadow on the retina. These floaters usually appear as transparent circles or tadpoles and stay permanently in your eye.

Sometimes, small hemorrhages in the eye can cause floaters as red blood cells enter the vitreous. This can occur if the gel pulls on blood vessels located in the retina. These floaters might take on a smoky appearance and disappear as the blood is absorbed.

Lastly, floaters can be caused by shrinkage of the vitreous gel that occurs naturally as we age. As the vitreous pulls away from the retina, bits of debris can enter the gel and become floaters. These usually look like cobwebs.

Floaters are particularly pronounced if you gaze at something particularly bright, such as a piece of white paper or a blue sky. You’ll notice that they move as your eyes move and appear to zoom across your eye as you try to look at them directly.

Floaters are usually just an annoyance that people get used to, but sometimes they can hamper vision and therefore require surgery. This procedure involves removing the vitreous and replacing it with a saline liquid.