Floaters are considered anything that floats or drifts in the vision. There is a large variety of floaters and some are characteristic of certain eye conditions. The way to tell the difference between a floater and a blind spot in the vision is that a floater will continue to drift in the vision after the eye stops moving, but a blind spot will stop moving as soon as the eye stops.
Common aging floaters. These usually present as one or two blobs, strands, cobwebs, or “amoebas” floating in the vision. They often develop fairly suddenly and can be associated with flashing lights. They are usually the result of shrinkage and liquification of the vitreous gel, which is common with aging and in nearsighted patients. Floaters can persist for a long time, even indefinitely, but in most cases they tend to improve over time. As the gel continues to liquify, the floaters tend to settle and move away from the center of vision. The brain tends to screen them out at this point and, although they are still there, they are much less bothersome and noticeable.
Pathological floaters. When multiple small floaters are seen, dozens or hundreds, this is more likely to be associated with a more serious abnormality. This usually starts suddenly, but in some conditions it can slowly get worse over a period of days or weeks. These are often seen best against a bright background, such as the sunny sky. These can occur with retinal tears and detachments, bleeding into the eye (vitreous hemorrhages), and inflammation or infection in the eye. They can also occur in a condition known as “Asteroid hyalosis” in which small white particles accumulate in the eye like a small snow storm. This condition is not harmful to the eye and most people tolerate the floaters well, but occasionally the floaters can be come very bothersome and have to be surgically removed.
When many small floaters appear suddenly this is of greater concern than a few larger floaters. If you have never had floater in the past we would recommend that you schedule a dilated examination of the eyes with an ophthalmologist. There is no way to make a definitive diagnosis without an examination. This is more urgent with many small floaters than with one or a few larger floaters, especially if they have been present and unchanged for weeks or months and are not associated with any other visual symptoms or pain.