Sight + Sound, Fall 2020
by Craig Smith
Why am I seeing Floaters?
Consider the eye or eyeball as a camera with a lens in the front and film in the back. The retina works like the film in a camera and lines the inside of the eyeball as a wallpaper. The central cavity of the eyeball is filled with a gel called vitreous. The vitreous gel is like eye white, clear, and gooey. The vitreous serves an essential function of nourishing the retina as it develops when one is still in the womb.
As we age, the vitreous gel begins to liquefy, and it pulls away from the retina. In nearsighted people, this can actually occur earlier in life. This separation of the vitreous from the retina may be very subtle, or it may be very obvious. When the gel separates, it is often like pulling a piece of tape from your wallpaper. The tape may pull a few flecks of paper or paint chips from the wall. When the vitreous gel pulls away from the retina, it may pull some “paint chips” from the retina. This often appears as a ring or cobwebs. When you look at something bright like a computer screen, a newspaper, or the sky, you may see these cobwebs floating in the vision. They are never seen in dim lighting or a dark room. In order to see these floaters, there must be a lot of light entering the eye. In a sense, the floaters are casting a shadow on the retina. This process of separation of the vitreous gel from the retina is called Posterior Vitreous Detachment or PVD. This is not the same as a retinal detachment.
Why do I see Flashing Lights?
When the vitreous gel pulls on the retina, there is never any pain or headache. However, this pulling can stimulate the retina and produce a flash of light. These light flashes tend to be very brief, like a lightning streak, often appearing in the upper part of your vision. Although brief, these flashes may be repetitive. Interestingly, these flashes tend to only be seen in dim light. The flashes of light from a vitreous separation (PVD) are very different from the type of light flashes seen with an ocular migraine. Ocular migraine flashes tend to last much longer, occur in daylight, and are usually very geometric in configuration.
What are the risks of a Posterior Vitreous Detachment?
When the vitreous gel separates from the retina in addition to creating floaters, in some people, the retina may actually tear, usually in a horseshoe shape. There are many blood vessels within the retina that serve to nourish it. When the retina tears, it may also tear a blood vessel. When this occurs, the eye can fill with blood, which looks like reddish-black smoke. Sometimes the bleeding can be very intense and totally block the vision. An untreated retinal tear can lead to a retinal detachment.
How do you treat a Retinal Tear?
When a person has a sudden onset of floaters and flashing lights, this is a sign of an acute posterior vitreous detachment or PVD; they need to have an urgent dilated retinal examination to look for a retinal tear. If a retinal tear is detected, it must be treated with either laser or cryotherapy (using a freezing pencil). Without treatment, a retinal tear can develop into a retinal detachment.
How do you treat a Vitreous Hemorrhage?
When the vitreous hemorrhage is really dense, not only does it block a person’s vision, it also blocks our ability to see the retina. When we are unable to see the retina, then a person can possibly have a retinal tear. Again, an untreated retinal tear can lead to a retinal detachment. Therefore, we will often recommend surgery to remove the blood, simply to allow us to examine the retina for tears that need to be treated. This surgery is called a Vitrectomy and it is done in the operating room.
How do you treat a Retinal Detachment?
Consider the retina as the wallpaper inside the eyeball. In order to remove wallpaper, one must use steam to get beneath the seam and break the seal, and it peels away. The retina is “seamless.” In order for the retina to detach, there must be a defect for fluid to seep beneath the retina and create the detachment. A PVD occurs as the vitreous gel begins to age or liquify. When there is a tear in the retina, this liquified gel will seep through the retinal tear, leading to the formation of a retinal detachment.
Once the retina detachment occurs, it cannot be treated with laser or a freezing treatment alone, and surgery is performed in the operating room. Sometimes a scleral buckle or band is placed around the eye, and in other situations, a vitrectomy is performed to remove the gel. Then a gas bubble is injected into the eye to hold the retina in place, and laser treatment is applied. In some instances, a small retinal detachment can be fixed in the office with the injection of a gas bubble followed by laser treatment a day or two later.
My floaters are really bothersome. What can be done about them?
After a couple of months after the development of floaters, the risk of getting a retinal tear and detachment are significantly reduced, but the floaters may still be present and very annoying. Over time, these floaters tend to shrink just a bit. Fortunately, most people are able to adapt and ignore these floaters. Sometimes people find these floaters to be almost incapacitating. There are advertisements for laser treatment of floaters. For some people, this treatment may be successful, but there are some associated risks, such as damage to the retina. Other times the laser will break-up the larger floaters and create zillions of very small floaters, which can be worse. Vitrectomy surgery can be performed to remove floaters, but it should be considered an option of last resort. The risks of a vitrectomy in an eye with floaters and 20/20 vision may be substantial as they include infection, bleeding, glaucoma, cataract formation, and retinal detachment. Some of these conditions can lead to blindness.