Floaters are symptoms caused by opacities in the vitreous (the transparent gel-like tissue filling the eyeball) projecting onto the retina. Against bright backgrounds such as white walls, bright skies, or windows, objects like mosquitoes, soot, or rings appear to drift with eye movements.
Floaters are one of the most common complaints in ophthalmology outpatient clinics 3). The underlying causes range from age-related physiological changes to urgent conditions such as retinal tears and retinal detachment. Therefore, it is important to carefully assess the nature of symptoms, onset, and accompanying symptoms to avoid missing pathological floaters.
Blue field entoptic phenomenon is a phenomenon in which small white dots appear to move randomly in the visual field when looking at a bright blue light such as a blue sky, and is distinguished from floaters. This is the perception of the movement of white blood cells within the retina and is not pathological.
Posterior vitreous detachment (PVD) is an age-related change that occurs frequently in people over 50 and is the most common cause of floaters. Reports indicate that about 14% of patients with acute symptoms of PVD are found to have retinal tears 1), and it is not uncommon for it to be asymptomatic. The combination of unilateral acute floaters and photopsia requires fundus examination 3).
Physiological Floaters
Definition: Caused by age-related posterior vitreous detachment (PVD) or minor fibrous vitreous opacities.
Characteristics: Not a target for treatment. They are most noticeable immediately after PVD, but as vitreous liquefaction progresses, the prepapillary glial ring (Weiss ring) moves away from the retina, and symptoms gradually diminish.
Movement with gaze changes: Floaters move in conjunction with eye movements.
Pathological Floaters
Definition: Associated with conditions such as retinal tear, retinal detachment, vitreous hemorrhage, or uveitis.
Characteristics: Require active treatment. Often accompanied by a sudden increase in floaters, tobacco dust, photopsia, or visual field defects.
Urgency: Depending on the underlying cause, emergency surgery may be necessary.
| Feature | Physiological Floaters | Pathological Floaters |
|---|---|---|
| Onset pattern | Gradual (weeks to months) | Sudden (days to hours) |
| Number and appearance of floaters | Few, ring-shaped, thread-like | Many, smoke-like (tobacco dust) |
| Associated photopsia | Usually none | Present (tractional) |
| Visual field defect | None | Possible (retinal detachment) |
| Visual acuity loss | Usually none | Possible (vitreous hemorrhage, etc.) |
| Need for treatment | Not needed (observation) | Needed (treatment according to underlying cause) |
Note that vitreous opacities in asteroid hyalosis (calcium crystal deposits in the vitreous) are an exceptional disease that is often not perceived as floaters.
Physiological floaters do not require treatment and often become less noticeable as vitreous liquefaction progresses. Pathological floaters may improve with treatment of the underlying cause. Typical treatments include laser photocoagulation for retinal tears, surgery for retinal detachment, and treatment of the cause of vitreous hemorrhage. Active treatment for physiological floaters (YAG laser vitreolysis, vitrectomy) is considered only in limited cases when quality of life is significantly impaired.
| Underlying disease | Main features | Urgency |
|---|---|---|
| Posterior vitreous detachment (PVD) | Most common. Age-related separation of vitreous from retina. Typical Weiss ring. High frequency in those aged 50 and older | Low (but need to check for tear complication) |
| Retinal tear | The retina is torn by vitreous traction during PVD. Often accompanied by tobacco dust and photopsia2) | High (urgent fundus examination, laser photocoagulation) |
| Retinal detachment (rhegmatogenous) | Fluid enters the subretinal space through a retinal tear. Visual field defect, curtain-like visual field loss4) | Emergency (surgery) |
| Vitreous hemorrhage | Mainly caused by diabetic retinopathy and retinal vein occlusion5). Sudden increase in floaters and decreased vision | High (investigate cause, treat) |
| Uveitis | Inflammatory cells in the vitreous are perceived as floaters. May be accompanied by redness and eye pain | Moderate to high (control inflammation) |
| High myopia (pathological myopia) | Vitreous liquefaction progresses from a young age, making floaters more likely6). Also at high risk for peripheral retinal degeneration | Low to moderate (regular follow-up) |
| Urgency Level | Combination of Symptoms | Recommended Action |
|---|---|---|
| Same-day visit | Visual field defect, tobacco dust, photopsia combined, sudden increase in floaters with vision loss | Visit an ophthalmologist on the same day. A facility capable of emergency care is preferable. |
| Early visit (within a few days) | Sudden onset of floaters, clear increase in number of floaters, change in shape | Visit an ophthalmologist within 1 to 3 days. |
| Regular follow-up | Pre-existing floaters unchanged, only swaying against bright background | Continue regular eye examinations |
Within 6 weeks after onset of PVD, the risk of retinal tear is highest 2), and if symptoms change during this period, prompt medical attention is required.
A sudden increase in floaters or change in their characteristics (increase in number, change in shape, appearance of new black spots like tobacco dust) may indicate pathological floaters. Especially if photopsia occurs simultaneously, early ophthalmologic examination is necessary as a warning sign of retinal tear. If pre-existing floaters continue unchanged, they are likely physiological, but regular fundus examinations are recommended.
After visiting an ophthalmologist, the first step is to determine whether the floaters are physiological or pathological. A vitreous examination using a slit-lamp microscope and a non-contact biconvex lens is performed to check for the presence of a prepapillary glial ring (Weiss ring) as an indicator of PVD and to assess vitreous opacities.
In vitreous examination, it is important to narrow the slit beam width and maximize illumination intensity to dynamically observe the vitreous movement. If only PVD is present without obvious vitreous opacities other than the prepapillary glial ring, physiological floaters can be diagnosed. However, if tobacco dust, hemorrhage, or flare is observed, a detailed fundus examination is necessary.
After instilling mydriatic drops, the peripheral fundus is examined extensively to check for retinal tears, retinal detachment, and vitreous hemorrhage.
| Condition | Treatment | Details |
|---|---|---|
| Physiological floaters | Observation | No treatment needed. Symptoms may decrease as vitreous liquefaction progresses. |
| Physiological floaters (significantly reduced QOL) | YAG laser vitreolysis | RCT reported significant symptom improvement compared to sham control (p=0.02)7). Limited indications. |
| Physiological floaters (severe QOL impairment) | Vitrectomy (vitreous surgery) | High symptom improvement rate, but surgical risks (cataract, retinal detachment, etc.) must be fully considered8). |
| Retinal tear (tear only) | Laser photocoagulation | Coagulates around the tear to prevent progression to retinal detachment. |
| Retinal detachment (rhegmatogenous) | Vitrectomy / Scleral buckling4) | Early surgery improves visual prognosis. Emergency response required. |
| Vitreous hemorrhage | Treatment of underlying disease (DR, RVO, etc.)5) | If hemorrhage does not resolve, consider vitrectomy |
| Uveitis | Inflammation control (steroids, etc.) | Workup and treatment of underlying disease required |
When dilating drops (e.g., tropicamide) are used, the pupils usually return to normal within 4 to 6 hours. During this time, light appears bright and near vision is blurry, so driving a car or bicycle should be avoided. It is recommended to bring sunglasses. The effect of dilating drops varies among individuals, and recovery may take 6 to 8 hours.
The vitreous is a transparent gel-like tissue that fills the eye, composed mainly of collagen fibers and hyaluronic acid. With aging, collagen fibers aggregate and degenerate, leading to vitreous liquefaction (syneresis). The liquefied areas form lacunae, and the surrounding residual gel becomes opaque, scattering light. This opacity projects onto the retina and is perceived as floaters.
As vitreous liquefaction progresses, the adhesion between the vitreous and retina weakens, and eventually the posterior vitreous membrane separates from the retina (posterior vitreous detachment: PVD). Immediately after PVD occurs, the prepapillary glial ring (Weiss ring) is located just above the retina, causing strong perception of floaters. As vitreous liquefaction further progresses to complete PVD, the Weiss ring moves away from the retina, and symptoms tend to diminish.
During PVD, in areas where the vitreous and retina are locally strongly adherent (e.g., lattice degeneration), traction forces concentrate when the vitreous separates, potentially tearing the retina (retinal tear)2). This traction stimulates the retina and is perceived as photopsia. If fluid enters the subretinal space through the tear, it can progress to rhegmatogenous retinal detachment4).
In high myopia, the eyeball volume increases due to axial elongation, so vitreous liquefaction progresses from a young age 6). In addition, lattice degeneration and retinal tears in the peripheral retina are more frequent, and the onset of floaters tends to occur at a relatively younger age.
Even when floaters do not cause vision loss, they can have a significant impact on patients’ mental burden and quality of life. In a study by Wagle et al. (2011), the utility value associated with floaters averaged 0.98, but patients with more severe symptoms showed significantly lower QOL scores 9). It is important not to treat floaters as a minor symptom and to listen carefully to patients’ complaints.
In an RCT by Shah et al. (2017), YAG laser vitreolysis for symptomatic vitreous opacities resulted in significant symptom improvement compared to sham control (53.3% vs 8.7%, p=0.02) 7). However, the procedure is highly dependent on the operator’s skill, and there are risks of complications (increased intraocular pressure, lens damage, retinal damage), so careful selection of facilities and indications is important.
A treatment method involving intravitreal injection of an enzyme (ocriplasmin) to chemically release vitreous traction is being studied. In an RCT by Stalmans et al. (2012), the efficacy of ocriplasmin for vitreomacular traction and macular hole was demonstrated 10). Its application to floaters themselves is still at the research stage.
Byer et al. (1994) showed in a natural history study after PVD onset that the risk of retinal tears is highest immediately after the onset of posterior vitreous detachment 2). Subsequent studies have indicated that follow-up observation within 6 weeks after the onset of acute symptomatic PVD is a key strategy to prevent tears and detachment, and standardization of follow-up timing is being promoted 3).
