The harmless 'floaters' popping up in your vision could be a sign of permanent eye damage, a new study has found.
Studies estimate as many as three in four Americans occasionally have tiny specks or cobweb-like shapes called vitreous floaters in their eyesight.
These floaters are caused by fibers of collagen, a structural protein, clumping together in the eye's gel-like substance called the vitreous, which sits behind the lens and in front of the retina.
While most common with age and nearsightedness, floaters are usually harmless, and the brain eventually learns to ignore them.
But researchers in the Netherlands have warned that the sudden onset of floaters could be a sign of retinal detachment, which occurs when the light-sensitive retina pulls away from the back of the eye.
Without immediate surgical or laser treatment, retinal detachment can cause permanent vision loss.
Other signs of retinal detachment include flashes of light and dark shadows or curtains moving across the field of vision.
Roughly 28,000 Americans suffer retinal detachment each year, which is usually caused by eye injuries, severe nearsightedness and aging.
The study, published earlier this month in Annals of Family Medicine, looked at nine years' worth of electronic health records from seven family medicine practices in the Netherlands, covering about 42,000 patients.
Researchers from Radboud University Medical Center in Nijmegen identified 1,181 visits involving 1,089 patients 18 and older who went to the doctor for new floaters, flashes of light or both.
The team sorted the patients into three groups: floaters only, flashes of light only or both symptoms at the same time.
About 61 percent of participants were women, and 57 percent fell between ages 50 and 70, a time during which the vitreous naturally shrinks and pulls away from the retina.
This can trigger floaters and potential tears.
Of the 1,181 visits, 77 ended with a diagnosis of retinal detachment or retinal tear, which is a break in the retina that can eventually cause detachment.
Among participants who only had flashes of light, 4.7 percent had a retinal detachment or tear compared to 6.1 percent of those with only floaters. Patients with both symptoms together had the highest rate of detachment or tear at 8.4 percent.
This means patients with both symptoms together were 56 percent more likely to have retinal detachment or tear compared to those who only had flashes of light.
Additionally, patients who experienced multiple floaters had a 19.8 percent chance of retinal detachment, and that risk climbed to 29.4 percent when the floaters were accompanied by flashes.
There were also 36 cases involving other serious conditions such as cataracts, bleeding in the eye and stroke-related events.
However, the study authors caution that most floater episodes are not a sign of a medical emergency.
The most common diagnosis in the study was simply 'floaters,' accounting for 36.7 percent of all visits, and the next most common, at 32.3 percent, was harmless, age-related separation of the vitreous from the retina.
About 10 percent of visits were also attributed to migraine, which can cause visual auras and disturbances.
The researchers urged family medicine physicians to urgently refer any patients who experience sudden onset of floaters, especially when accompanied by flashes, to look for retinal detachment.
Retinal detachment can be diagnosed through dilated eye exams from an ophthalmologist or optometrist. It's treated with prompt surgery ideally within 24 to 48 hours. Procedures may include vitrectomy, which removes the vitreous damaging the retina, or a scleral buckle, done by placing a silicone band around the outside of the eye to support tears and reattach the retina.
In some cases, laser therapy can weld the retina back to the eye wall.