What are Floaters?
Have you ever noticed something swimming in your field of vision? It may look like a tiny worm, spot or transparent cobweb. When you try to take a closer look, it disappears, only to reappear as soon as you shift your glance. This is a common, usually normal, phenomenon known as a floater. While floaters may look like a mosquito or a live worm in front of you, they are not actually external objects in the world. In fact, they are particles that exist inside your eyeball.
The most common type of floater results from a normal, age-related change of the eye called posterior vitreous degeneration or detachment. The inside of the eyeball is comprised of a jelly-like substance called the vitreous humor. When we are born, the vitreous has a gel-like consistency and parts of it are attached to the inner back lining of the eyeball, called the retina. As we age, the vitreous gel begins to contract and liquefy, detaching itself from the neurosensory retina. During this process of liquefaction and contraction, pieces of the undissolved gel are left behind. These undissolved gel particles floating in the eye cast their shadow on the retina, which we ultimately perceive as a floater in our field of vision.
Floaters can drift along with your eye movement and seem to bounce when the eye comes to a stop. They are particularly noticeable when looking at a uniform bright surface such as a blank computer screen, snow, a white wall or a clear sky where the consistency of the background makes them easier to distinguish.
When Floaters are Serious
Noticing a few floaters from time to time is common and usually not a cause for concern. However, there are times when floaters and flashes can be a sign of a medical emergency. If you suddenly see a new shower of floaters and many spots in your vision, especially if they are accompanied by flashes of light, it is important to seek medical attention immediately from an eye care professional.
The sudden appearance of these symptoms could mean two things: the vitreous is pulling away from the retina (posterior vitreous detachment) or that the retina itself is becoming dislodged from the back of the eye’s inner lining (retinal detachment). As mentioned earlier, a posterior vitreous detachment is a normal age-related change of the eye. A posterior vitreous detachment often is not a medical emergency even when a shower of floaters appears suddenly, as long as there are no complications. Sometimes however, when the vitreous gel separates itself from the retina, it can tug on the delicate retina and create a small tear or hole in it. When the retina is torn, vitreous can enter the opening and push the retina farther away from the inner lining of the back of the eye. This is called a retinal detachment, a process that can potentially cause irreversible vision loss if not treated immediately.
What Causes Floaters?
While posterior vitreous degeneration is easily the most common cause of eye floaters, blood particles or inflammatory particles in the vitreous humor can also be perceived as floaters. Bleeding in the back of the eye can result from a number of different conditions, most commonly, diabetic retinopathy. In proliferative diabetic retinopathy, new fragile blood vessels grow into the vitreous humor and bleed easily, lodging blood particles into the vitreous gel. Other causes of bleeding in the back of the eye include trauma, central retinal vein occlusion, hypertensive retinopathy, and cytomegalovirus retinopathy. Inflammation of the eye, also known as uveitis, can also be a cause of eye floaters. Inflammation of the eye can be caused by a bacterial infection, a viral infection, an autoimmune condition, trauma, or can be idiopathic in nature. In intermediate and posterior uveitis, white blood cells and inflammatory cells collect in the intermediate portion of the eye as well as the vitreous humor, which can be perceived as floaters.
While floaters can be extremely annoying to the individual living with them, they are merely harmless. With time, patients will learn to adapt to them and the floaters will become less bothersome. In most cases, no treatment is necessary. One of the treatments for floaters is an invasive surgery called anterior vitrectomy, where the vitreous humor is removed from the eye and replaced with a sterile clear fluid. However, the risks of anterior vitrectomy outweigh the benefits for eye floater treatment. A newer form of treatment called laser vitreolysis is an in-office procedure that projects a laser into the pupil and breaks apart large floaters. In some cases, the laser will break apart a large floater into many tiny floaters, which can potentially be even more bothersome to the patient. Therefore, it is generally best to educate the patient to allow themselves time to adapt.