Eye floaters are caused by tiny clumps of collagen fibers floating inside the gel-like substance that fills your eyeball. As this gel ages and breaks down, these fibers cast shadows on the light-sensitive tissue at the back of your eye, producing the drifting spots, squiggly lines, or cobweb shapes you see. Floaters affect somewhere between 27% and 76% of people depending on the study, and most cases are harmless, though a sudden increase can signal something serious.
How the Gel Inside Your Eye Breaks Down
Your eye is filled with a clear, jelly-like substance called the vitreous. When you’re young, it has a firm, consistent texture. Millions of microscopic collagen fibers run through it, helping it hold its shape. Over time, the vitreous gradually liquefies. As it does, those collagen fibers shrink, tangle together, and form small clumps. When light enters your eye, these clumps block some of it and cast tiny shadows onto your retina. Those shadows are what you perceive as floaters.
This process of liquefaction is called vitreous syneresis, and it’s as universal as getting wrinkles. It happens slowly, which is why many people notice a floater here or there over the years without any dramatic change.
Posterior Vitreous Detachment
The most significant age-related cause of floaters is posterior vitreous detachment, or PVD. As the vitreous continues to shrink, it eventually pulls away from the retina entirely. The collagen fibers connecting the gel to the retina snap, and the vitreous separates and floats freely inside the eye. This usually produces a noticeable burst of new floaters, sometimes accompanied by brief flashes of light.
PVD happens to most people by age 70 and is considered a normal part of aging. It often occurs earlier in people who are nearsighted, have had eye surgery, or have experienced eye injuries. The floaters from a PVD tend to be most bothersome in the first weeks and gradually become less noticeable as your brain learns to filter them out, though they don’t truly disappear.
Why Nearsightedness Increases Your Risk
If you’re significantly nearsighted (myopic), your eyeball is physically longer than average. Research has shown that the longer the eye, the greater the density of debris in the vitreous and the worse the visual impact. That elongated shape puts more mechanical stress on the vitreous gel, causing it to break down and detach from the retina earlier in life. This is why people in their 30s and 40s with strong glasses prescriptions often develop floaters well before their peers do.
Inflammation and Infection
Not all floaters come from aging. Inflammation in the back of the eye, a condition called posterior uveitis, can release inflammatory debris and white blood cells into the vitreous. These particles scatter light the same way collagen clumps do, creating floaters. Posterior uveitis can result from autoimmune disorders, infections, or other inflammatory diseases. Floaters caused by inflammation tend to appear alongside other symptoms like eye pain, redness, or blurred vision, which helps distinguish them from the ordinary age-related kind.
Bleeding Inside the Eye
When blood vessels in the eye leak or rupture, blood cells enter the vitreous and create floaters that may look like a sudden shower of dark spots or a hazy, cloudy film across your vision. This is called a vitreous hemorrhage. Several things can cause it: a direct blow to the eye, the vitreous pulling away from the retina and tearing a small blood vessel in the process, or diseases like diabetic retinopathy that weaken blood vessels over time. Even excessive straining (like heavy lifting or forceful coughing) can occasionally break a fragile vessel. Vision loss from vitreous hemorrhage can range from mild floaters to nearly complete obstruction, depending on how much blood enters the eye.
Floaters After Eye Surgery
Cataract surgery is one of the most common triggers for new floaters. The most frequent cause is a posterior vitreous detachment that occurs in response to the procedure. These floaters typically appear about a day after surgery and fade over the following months. In some cases, the floaters were already present before surgery but invisible because the cloudy cataract was blocking them. Once the lens is replaced and vision sharpens, pre-existing floaters suddenly become obvious.
Any intraocular surgery carries some risk of triggering vitreous changes, so new floaters after an eye procedure are not unusual.
When Floaters Signal an Emergency
Most floaters are benign. But a sudden shower of new floaters, especially paired with flashes of light or a shadow creeping across your peripheral vision, can indicate a retinal tear or retinal detachment. When the vitreous pulls away from the retina, it sometimes tears the tissue. Vitreous fluid can then seep through that tear and lift the retina away from the back of the eye. Left untreated, retinal detachment causes permanent vision loss.
The specific warning signs to watch for:
- A sudden burst of many new floaters, different from the one or two you may be used to
- Flashes of light in one or both eyes
- A dark curtain or shadow spreading across part of your vision
- Rapidly worsening peripheral vision
Any of these symptoms calls for an immediate eye exam. Retinal tears caught early can often be sealed with laser treatment before a full detachment develops.
How Floaters Are Diagnosed
An eye doctor checks for floaters using a dilated eye exam. Drops widen your pupil so the specialist can see the back of your eye clearly and look for vitreous debris, retinal tears, or signs of detachment. The exam itself is straightforward and takes about 20 to 30 minutes, though your vision will be blurry for a few hours afterward from the dilation drops.
Treatment Options
Most floaters don’t require treatment. They tend to settle below your line of sight over weeks or months, and your brain gradually tunes them out. For floaters that remain large, dark, and disruptive to daily life, two interventions exist.
Laser vitreolysis uses a focused laser to break apart collagen clumps inside the eye. In a clinical trial, 54% of patients reported improvement after a single session. Many people need two or more sessions for meaningful results. The procedure carries small risks including increased eye pressure, retinal tears, and lens damage, though in the trial no significant difference in adverse events was found between the laser group and a placebo group.
Vitrectomy is a surgical procedure that removes the vitreous gel entirely and replaces it with a saline solution. It’s highly effective, with patients typically achieving clear vision within a week of surgery. But it’s a more invasive step. Three small incisions are made in the eye, which carries a small risk of infection. Vitrectomy also accelerates cataract formation because removing the vitreous changes the oxygen environment inside the eye. The most concerning complication is retinal detachment, reported in up to about 11% of cases in some published studies. Because of these risks, vitrectomy is generally reserved for people whose floaters severely impair their quality of life or vision.