Findings from a recent study published in Annals of Family Medicine show that vitreous floaters, with or without flashes, carry a clinically meaningful risk of retinal detachment (RD) in primary care.
The data challenges a long-standing assumption: that flashes are the more important warning sign.
Give me some background first.
Floaters are small clumps of vitreous gel inside the eye that drift through the vision, often appearing as small moving spots, clouds, or cobweb-like shapes Flashes (photopsias) are perceptions of light without an external stimulus.
Both can signal posterior vitreous detachment (PVD), which is common with aging but can also mean something more serious like a retinal tear or detachment.
Go on …
Current Dutch primary care guidelines list flashes and vision loss as the key alarm symptoms for urgent referral.
However, floaters get less emphasis—and ophthalmology data has shown that acute floaters may carry a stronger association with retinal tears than flashes do.
- The gap: Until now, no study had examined the association between floaters, flashes, and RD specifically in a primary care population.
Now, talk about the study.
A team at Radboud University Medical Center in the Netherlands ran a retrospective cohort study using data from the Dutch Family Medicine Network.
- They pulled electronic health records from seven family practices covering roughly 42,000 patients, spanning December 2012 to July 2021.
The aim: Calculate the absolute risk (AR) and relative risk (RR) of RD in patients presenting with new-onset floaters, flashes, or both.
Flashes alone served as the reference group for relative risk calculations.
Who was included in the study?
All new episodes where floaters or flashes were the reason for the encounter in adults aged ≥18 were included. Cases were identified by International Classification of Primary Care (ICPC) codes and confirmed through medical record review.
The final sample included a cohort of 1,181 episodes from 1,089 patients across 184,885 patient-years (the cumulative time all enrolled adults were tracked at their family practices).
- Of those 691 presented with floaters, 170 with flashes, and 320 with both floaters and flashes.
- Demographics: The study skewed female at 60.6%. The majority (57.1%) were aged 50 to 70.
Episodes were further categorized by duration (acute, defined as ≤14 days, vs. chronic) and number of floaters (many, defined as ≥10 floaters or a cloud/haze/curtain, vs. few).
Findings?
A total of 77 episodes (6.5%) resulted in a retinal tear or retinal detachment.
Absolute risk by symptom type: Floaters alone had an AR of 6.1%. Flashes alone, 4.7%. Floaters and flashes combined, 8.4%.
- Floaters consistently carried a higher absolute risk than flashes, whether they appeared alone or alongside flashes.
Acute symptoms drove the risk up: Among patients with acute floaters (≤14 days), AR jumped to 8.5%. For acute floaters and flashes together, it reached 11.3%.
Many floaters were an even stronger signal: Patients reporting ≥10 floaters, a cloud, haze, or curtain had an AR of 19.8% for floaters alone and 29.2% for floaters and flashes combined.
Tell me more.
Relative risk calculations (how much that chance changes compared to another group) used flashes alone as the reference group.
After adjusting for age and gender, the overall RR for floaters alone was 1.29 (95% confidence interval [CI], 0.62 to 2.67), and for floaters and flashes combined it was 1.54 (95% CI, 0.72 to 3.29).
- Neither reached statistical significance.
And where did the numbers get significant?
Specific subgroups showed substantially elevated relative risk compared to flashes alone.
Acute floaters and flashes: RR 2.39 (95% CI, 1.11 to 5.15). Many floaters alone: RR 4.20 (95% CI, 1.87 to 9.40). Many floaters and flashes: RR 6.20 (95% CI, 2.47 to 15.55).
In other words: A patient showing up with a sudden onset of numerous floaters had roughly four to six times the risk of RD compared to someone presenting with flashes alone.
Anything else worth flagging?
The study found 36 different final diagnoses across the full cohort.
The most common outcome was a symptom-only diagnosis (vitreous floaters/spots/flashes) at 36.7%, followed by PVD at 32.3%. Migraine came in third at 9.8%.
Limitations?
Considering this was a retrospective design relying on EHRs, the usual caveats around missing data apply.
- Several additional variables (vision loss, visual field loss, Amsler grid results) were not consistently documented.
And a classification challenge: Floater quantity and duration were based on textual descriptions in clinical notes, not standardized assessments—which introduced some information bias.
There was also no control group of patients without floaters or flashes.
- As such: This limited the ability to draw conclusions about general population risk.
Expert opinion?
Floaters, not flashes, should be treated as the primary alarm symptom for RD in primary care, the study authors reasoned.
They argued that recent onset and high floater count are the two characteristics that matter most for risk stratification.
Also noted was the third most common diagnosis among these patients (migraine), which may explain some reluctance around an ophthalmic referral.
- The authors emphasized that clear safety-net instructions are essential even when migraine is the working diagnosis.
Take home.
For family physicians triaging patients with new visual symptoms: this study makes the case that floaters are a stronger predictor of RD than flashes, particularly when they’re acute or numerous.
Patients presenting with ≥10 floaters, a cloud, a haze, or a curtain, especially within the first 14 days of onset, warrant urgent referral to rule out retinal detachment.
With this in mind: Current guidelines emphasizing flashes over floaters may need updating.