Floaters are a common optical phenomenon.
Floaters often look like small specks, strands, “cobwebs”, or other shapes floating in front of your eyes. They are more noticeable when you look at a light colored background (such as the sky, a window, a white wall).
Floaters are tiny clumps of cells floating inside your eyes in the vitreous, a gel-like substance that occupies the posterior chamber of the eye. Usually they are not dangerous and result from deterioration of the vitreous fluid due to age, injuries, surgeries, and certain eye diseases. However, a suddent new onset of flashing lights and/or floaters can result from a retinal tear or detachment which should be evaluated and treated as soon as possible.
When we are young, the vitreous is transparent and is firmly attached to the retina. As we age, the vitreous begins to liquify causing areas of optical imperfections to develop. When struck by incoming light, these areas cast shadows on the retina and are perceived as spots, threads, or cobwebs floating in our vision. Though part of the normal aging process, floaters are more commonly seen in people who are nearsighted, or who have undergone certain types of eye surgery such as a cataract extraction.
As the vitreous continues to liquefy and collapse, it may pull away from the retina. This is known as a Posterior Vitreous Detachment (PVD) (not to be confused with a retinal detachment). The function of the retina is to respond to light. Therefore, any stimulation of the retina is perceived by the brain as light. During the process of liquefaction, collapse and detachment, the vitreous can "tug" on the retina. This mechanical stimulation of the retina is perceived by the brain as bursts of light and explains the momentary flashing or visual aura often accompanying the onset of "floaters."
A sudden onset of flashes and floaters can be most disturbing to patients, but in most cases it is benign. However, when the vitreous pulls away from the retina during a vitreous detachment, it can cause a tear in the retina, which will require treatment. Although occurrences of a retinal tear or detachment are less common, patients should not take the sudden onset of flashes and floaters lightly. Since there aren’t any pain receptors in the retina inside your eyes, you will not experience any pain or discomfort if this happens. A careful examination of the retina and vitreous through a dilated pupil is absolutely essential following the onset of "flashes and floaters" because your optometrist can determine if what you are seeing is harmless, or the symptom of a more serious problem.