Acute onset flashers and floaters

Background

Eye anatomy.
  • Photopsia is defined as a visual phenomenon characterized by the perception of flashes of light or flickering in the visual field[1][2]
  • Acute onset flashers and floaters is a common ED complaint, especially in older adults
  • The critical EM concern is ruling out retinal detachment and vitreous hemorrhage, which are sight-threatening
  • Most common cause is posterior vitreous detachment (PVD), which is benign but has ~10-15% risk of associated retinal tear
  • Risk factors for retinal detachment: myopia (nearsightedness), prior cataract surgery, prior retinal detachment in other eye, trauma, family history, increasing age

Clinical Features

Floaters

  • A sensation of gray or dark spots, cobwebs, or strands moving in the visual field
  • Caused either by light bending at the interface of fluid pockets in the vitreous jelly or cells/blood located within the vitreous
  • May persist for months to years
  • New onset of many floaters ("shower of floaters") or sudden increase in existing floaters is more concerning than a single new floater

Flashes (Photopsia)

  • Monocular, repeated, brief flashes of white light in the peripheral visual field
  • Related to traction on the peripheral retina from areas of tightly adherent vitreous jelly
  • Flashes occurring with movement or position change suggest mechanical traction (vitreous on retina)
  • Distinguish from migraine aura: migraine visual symptoms are typically binocular, with scintillating scotoma lasting 15-30 minutes, and often followed by headache

Red Flags for Retinal Detachment

  • "Curtain" or "shadow" coming across visual field (indicates retinal detachment in progress)
  • Dense new floaters or shower of floaters (may indicate vitreous hemorrhage from retinal tear)
  • Decreased visual acuity (suggests macular involvement)
  • Visual field deficit
  • Loss of red reflex on fundoscopy
  • Pigmented cells ("tobacco dust" / Shafer's sign) in anterior vitreous on slit lamp

Differential Diagnosis

Acute onset flashers and floaters

Posterior Vitreous Detachment (Most Common)

  • Age-related separation of vitreous from retina
  • Benign but 10-15% risk of associated retinal tear

Sight-Threatening

  • Retinal detachment: flashes, floaters, visual field curtain, decreased acuity
  • Vitreous hemorrhage: sudden dense floaters, decreased acuity, absent or diminished red reflex
  • Retinal tear (without detachment): may progress to detachment if untreated

Other

  • Migraine with visual aura (binocular, scintillating, lasts 15-30 min)
  • Ocular migraine (monocular, but transient)
  • Posterior uveitis (cells in vitreous, pain, redness)
  • Endophthalmitis (post-surgical, painful, decreased vision)

Evaluation

Bedside Exam

  • Visual acuity (each eye separately) — decreased acuity suggests macular involvement
  • Visual field confrontation test — detect curtain or field defect
  • Pupillary exam: RAPD suggests significant retinal pathology
  • Direct ophthalmoscopy: look for blood in vitreous (obscured view = vitreous hemorrhage), retinal tears, detached retina
  • Slit lamp exam: look for pigmented cells ("tobacco dust") in anterior vitreous — highly suspicious for retinal tear
  • Intraocular pressure: may be low with retinal detachment

Bedside Ultrasound (POCUS)

  • Ocular ultrasound is highly sensitive for detecting retinal detachment and vitreous hemorrhage
  • Retinal detachment appears as a bright membrane tethered to the optic disc
  • Vitreous hemorrhage appears as swirling echogenic material in posterior chamber
  • Can be performed at bedside when direct fundoscopy is limited (e.g., by vitreous hemorrhage obscuring view)

Retinal Images

Management

Retinal Detachment

  • Macula-on detachment (macula still attached): ophthalmologic emergency — same-day or next-day repair for best visual outcomes
  • Macula-off detachment: urgent but not emergent (macula already detached); repair within 24-72 hours
  • Position patient with detachment side down (gravity helps keep retina in place)
  • Emergent ophthalmology consultation

Vitreous Hemorrhage

  • Ophthalmology consultation within 24 hours
  • Head-of-bed elevation (allows blood to settle inferiorly, clearing visual axis)
  • Identify and treat underlying cause (diabetic retinopathy, retinal tear)

Posterior Vitreous Detachment (No Tear or Detachment)

  • Reassurance that floaters typically improve over time
  • Ophthalmology follow-up within 1-2 weeks (retinal tear can develop days to weeks after PVD)
  • Strict return precautions

Disposition

Referral of patients with presumed posterior vitreous detachment

Clinical Assessment Disposition
  • Floaters and/or flashes with “red flag” sign of acute Retinal Detachment
    • Monocular visual field loss (“curtain of darkness”)
  • Same-day (immediate) referral to retinal surgeon (minutes may matter)
  • New-onset floaters and/or flashes with high-risk features:
    • Subjective or objective visual reduction examination
    • Vitreous hemorrhage or vitreous pigment on slitlamp examination
  • Same-day referral to ophthalmologist or retinal surgeon
  • New-onset floaters and/or flashes without high-risk features
  • Referral to ophthalmologist within 1 to 2 weeks
    • Counsel patient regarding high-risk features
  • Recently diagnosed uncomplicated posterior vitreous detachment with
    • New shower of floaters
    • New subjective visual reduction
  • Rereferral to ophthalmologist to rule out new retinal tear or detachment
    • Contact ophtho to help determine urgency
  • Stable symptoms of floaters and/or flashes for several weeks to months, not particularly bothersome to the patient and without high-risk features
  • Elective referral to ophthalmologist
    • Counsel patient regarding high-risk features that should prompt urgent reassessment

Emergent Ophthalmology Consultation

  • Macula-on retinal detachment
  • Retinal tear identified on exam
  • Vitreous hemorrhage with suspected retinal detachment

Urgent Ophthalmology Referral (24-48 Hours)

  • Vitreous hemorrhage without retinal detachment
  • Macula-off retinal detachment
  • High-risk features (many new floaters, visual field changes, decreased acuity)

Routine Ophthalmology Follow-Up (1-2 Weeks)

  • Isolated posterior vitreous detachment with normal exam and acuity
  • Single new floater without associated flashes, visual field changes, or decreased acuity

Return Precautions (All Patients)

  • New or worsening floaters
  • New flashes of light
  • "Curtain" or shadow in peripheral vision
  • Decreased vision

See Also

Eye Algorithms

References

  1. ↑ Hollands H, et al. Acute-onset floaters and flashes: is this patient at risk for retinal detachment? JAMA. 2009 Nov 25;302(20):2243-9. PMID 19934426
  2. ↑ Powell SK, et al. Presentations to eye emergency departments with flashes and floaters differ dependent on incident solar radiation. Ir J Med Sci. 2023 Oct;192(5):2527-2532. PMID 36658378
  1. Hollands H, Johnson D, Brox AC, Almeida D, Simel DL, Sharma S. Acute-Onset Floaters and Flashes: is this patient at risk for retinal detachment? JAMA. 2009;302(20):2243-2249.
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