Patients who present to their primary care providers experiencing new-onset or multiple floaters in their vision could be at risk for retinal tears or detachment and should be referred promptly to an ophthalmologist, Dutch researchers found.

The risk is particularly high for people with more than 10 floaters and those whose eye issues began in the previous 2 weeks, according to the researchers, whose findings appear in the Annals of Family Medicine.

“Our results show that floaters (with or without flashes) represent a clinically relevant risk for [retinal detachment], especially with a recent onset or if there are many of them,” Floris van de Laar, MD, PhD, of Radboud University Medical Centre in Nijmegen, Netherlands , and his colleagues wrote. “Therefore, we recommend urgent referral of these patients to confirm or rule out” detachment.

van de Laar, family physician, said he got the idea to study the association when an ophthalmologist colleague mentioned patients with floaters were often referred to him too late and were already experiencing a detached retina. A pilot study they published in the Dutch journal Huisarts & Wetenschap in 2021 hinted at the association, which prompted this follow-up.

Posterior vitreous detachment (PVD), the separation of the posterior vitreous membrane from the retina, is a normal part of aging, van de Laar explained. Resulting symptoms include the onset of floaters and flashes. While PVD itself is harmless, about 6%-18% of patients experience complications such as vitreous hemorrhage, retinal tear, or retinal detachment, which can lead to permanent vision loss, he said.

van de Laar and his colleagues performed a retrospective cohort study of patients aged 18 years or older with new-onset floaters or flashes from the Family Medicine Network, a research collective of seven family physician practices and 35 family practices containing data for 42,000 patients, from December 2012 to July 2021. They included all new episodes that started with vitreous floaters or flashes as the reason for the visit. Floaters were defined as symptoms of vitreous floaters or black spots, including clouds, hazes, or moving curtains. Flashes were defined as beams of light or flickering light.

Reviewing electronic health records, they categorized 1181 episodes (1089 patients) into either floaters alone, flashes and floaters, or flashes alone. They looked at duration of symptoms (acute defined as 14 days or fewer) and number of floaters (many, defined as 10 or more, or described as a cloud or haze or curtain) as subgroups and calculated the relative risk for flashes alone as the reference group.

The researchers identified 77 episodes of vision-threatening retinal detachment that started with floaters alone and/or flashes (floaters, n = 42 [54.5%]; flashes, n = 8 [10.4%]; floaters and flashes, n = 27 [35.1%]). The absolute risk for detachment with floaters was 6.1%, 4.7% for flashes alone, and 8.4% for the combination of floaters and flashes.

The incidence of floaters was 5.5 per 1000 patient years, and of flashes, 2.7 per 1000 patient years. The adjusted relative risk for retinal detachment linked to floaters alone was 1.29 (95% CI, 0.62-2.67) and 1.54 (95% CI, 0.72-3.29) for floaters and flashes compared with flashes alone. However, significantly greater relative risks were found among those experiencing more than 10 floaters (4.20; 95% CI, 1.87-9.40), floaters and flashes occurring within the prior 2 weeks (2.39; 95% CI, 1.11-5.15), and “many” floaters and flashes (6.20; 95% CI, 2.47-15.55).

Ten episodes of retinal detachment resulted from a different reason for the exam than floaters or flashes, such as vision loss or visual field loss, for an overall incidence of retinal detachment of 0.47 cases per 1000 patient years. About 60% of participants were female, and the majority (57%) were aged 50-70 years.

Cases resulted in 36 diagnoses, the most common of which were vitreous floaters or spots or flashes that did not evolve into classifiable disease, PVD, and migraine.

The paper highlights simple questions to ask patients to get at a potential diagnosis, said Henry Bair, MD, MBA, ophthalmology resident at Wills Eye Hospital in Philadelphia.

“People don’t always describe floaters the same way,” Bair said. When he sees a patient who says they are experiencing floaters, he said, the first questions he asks are when it started and how many there are.

“When it’s a few larger floaters, I’m more reassured that it’s a PVD, which is basically the jelly in the eye peeling away from the retina,” he said. “That’s benign. It happens to almost everybody at some point in their lives, and there’s no need to treat for that.”

“What we worry about is the many floaters, hundreds of little floaters, because that is more suggestive of pigment or blood being released into the jelly in the eye,” Bair added, noting some patients describe it akin to a swarm of flies or mosquitoes.

The main takeaway from the study, however, is that it sets a benchmark for how many floaters clinicians should be concerned about, especially when combined with flashes. “That is reasonable grounds for same-day or next-day referral to an ophthalmologist,” he said.

van de Laar and Bair reported having no relevant financial disclosures.

Karen Blum is a freelance medical/science writer in the Baltimore area.