Floaters are the small spots you may occasionally see in your field of vision.
The medical name for floaters is muscae volitantes. Floaters can be seen in many different forms, including dots, threads, or cobwebs. Floaters may seem to dart away when you try to look at them.
Inside your eye, there is a clear, gel-like fluid called the vitreous. You may see floaters if some of the gel in your vitreous clumps together. Small flecks of protein or other material that were trapped in the vitreous when your eye was formed can also cause floaters. The floaters in your eye are seen as shadows by your retina. The retina is the light-sensitive inner layer of your eye.
Floaters are a natural part of the eye’s aging process. As you age, your vitreous gel shrinks and may detach from your retina. If this happens, it can cause a small amount of bleeding. This is a common cause for floaters in people who are very nearsighted or who have had cataract surgery. Floaters are not a definite sign of a retinal detachment.
Other not as common causes for floaters are other types of eye surgery, eye disease, eye injury, or crystal-like deposits that form in the vitreous.
Surgery to remove floaters is rare and only suggested for very severe cases. Generally, floaters are not treated and people who see floaters learn to ignore them. If a floater appears in your line of vision, you should move your eye around. This causes the fluid inside your eye to shift and allows the floater to move out of the way. Looking up and down may be more helpful for moving floaters than looking side to side.
Do not worry if you have a few floaters. Generally, a small number of floaters does not mean that you have a serious eye problem.
You need to see your eye doctor for an eye exam if a large number of floaters suddenly appears in your vision, or if they seem to worsen over time.
NOTICE: If the floaters appear along with flashes of light or if you have any vision loss, you should seek immediate medical attention. These could be signs of a serious condition, such as, retinal tears, hemorrhaging due to diabetes, high blood pressure, or uveitis (a kind of eye inflammation). It is important that you see a doctor because retinal tears and hemorrhaging can cause vision loss.
Source. Allaboutvision