Flashing And Floating

aka Ophthalmology Befuddler 012

A 65 year-old comes into the ED saying that he thinks ‘the jelly’ in his eye has ‘peeled off again’. He says he been seeing flashes of light as well as blobs and cobwebs floating in front of his right eye. He experienced the same thing about a year ago in his other eye. His visual acuity is similar in both eyes.


Q1. What is the differential diagnosis?
Answer and interpretation
  • Posterior vitreous detachment
  • vitreous haemorrhage
  • retinal break
  • retinal detachment
  • retinal hemorrhage

A bedside ultrasound shows this:

Q2. What is the likely diagnosis?
Answer and interpretation

Posterior vitreous detachment — the ultrasound shows fine linear and granular echogenicities in the posterior segment of the eye, which swirl around as the eye moves. There is no tethering to the optic disc.

This is consistent with vitreous debris seen in posterior vitreous detachment.

This is common in patients older than 60 years. With age the vitreous gel pulls away from the retina, which can lead to symptoms similar to those of retinal break, vitreous hemorrhage, and retinal detachment.

Q3. What are the features of this condition on history and examination?
Answer and interpretation


  • Presence of floaters, cobwebs, or blobs obscuring the visual field of the affected eye that change position with movement. Vision may be blurred.
  • Flashes of light — especially in the dark and located temporally.
  • Check for risk factors for a retinal break (see below).


  • Visual acuity — may be reduced
  • Red reflex — abnormal — floaters may be detected.
  • Slit lamp and ophthalmoscopy — look for discrete light grey to black opacities, may be in the form of a ring (a Weiss ring) or a broken ring over the optic disc. Get the patient to look up down and left right.
  • Check for the presence of retinal tears or detachment, retinal hemorrhage. Look for pigmented cells in the anterior vitreous (‘tobacco dust’) and retinal hemorrhages that may suggest these complications.

Q4. How often is a retinal break associated with a PVD, and what features are suggestive?
Answer and interpretation

About 10%

Suspect retinal tears if you see ‘tobacco dust’ in the anterior vitreous or evidence of retinal or vitreous hemorrhage.

Q5. What aspects of the history should be considered risk factors for a retinal break?
Answer and interpretation
  • past ocular surgery
  • previous retinal tear
  • family history
  • ‘‘curtain coming down’
  • high myopia

Q6. Describe the role of ultrasound in the assessment of the patient with ‘flashes and floaters’. How is ocular ultrasound performed?
Answer and interpretation

Ultrasound is highly specific and sensitive for the diagnosis of both retinal detachment and vitreous detachment. It is particularly useful for detecting retinal detachment when the retina is obscured by vitreous hemorrhage.

Ocular ultrasound should be performed by appropriately trained and accreditated practitioners. It is performed as follows:

  • The ocular exam is performed using a high frequency linear array probe with appropriate settings for the appropriate depth, high gain and high resolution.
  • Gel is placed on the probe and the patient closes their eyelids while the probe contacts the external surface of the eyelid. Enough gel should be applied so that the probe applies no pressure to the surface of the eyelid.
  • The structures of the eye are identified from front to back: lid, cornea, anterior chamber, iris, lens, posterior segment containing the vitreous humour, the retina and sclera, and the optic nerve.
  • The patient looks up, down, left and right at the sonographer’s request to check for movement of structures within the eye.

Features of vitreous detachment are:

  • the presence of an amorphous swirling cloud-like opacity the moves with ocular movement and is not tethered to the optic disk or retina

Features of retinal detachment are:

  • a delicate linear opacity attached to the posterior of the globe that is shown to be tethered to the optic disk when the eye moves

Q7. Describe the investigation and management of this condition.
Answer and interpretation

PVD requires no specific treatment.

However, a coexistent retinal tear requires repair and must be ruled out by an ophthalmologist.

Long-term ophthalmology follow up is required and the patient is warned to seek medical attention if they develop symptoms of retinal detachment.

What if the patient has markedly decreased visual acuity in the affected eye, a markedly reduced (almost black) red reflex, the fundus cannot be visualized on funduscopy, and you see something like this on ultrasound?

Q8. What is the likely diagnosis?
Answer and interpretation

Vitreous hemorrhage — the ocular ultrasound demonstrates the ‘washing machine’ sign. Blood (granular echogenicities) swirl with eye movement and settle when the eye is still.

Vitreous hemorrhage results from bleeding into the preretinal space or into the vitreous cavity. Ultrasound findings include:

  • Fresh mild hemorrhages — small dots or linear areas of low reflective mobile vitreous opacities
  • More severe and older hemorrhages — blood organizes and forms membranes.
  • Vitreous hemorrhages may also layer inferiorly due to gravitational forces.

Q9. What findings on history and examination are consistent with this condition?
Answer and interpretation


  • It may present like a retinal detachment — with floaters that progress over hours to severe visual loss without pain.


  • Visual acuity — markedly reduced
  • Red reflex — absent (black) or only partially present (reddish haze)
  • Pupils — RAPD may be present, but suggests a coexistent retinal detachment behind the hemorrhage.
  • Funduscopy — the view of the retina is obscured, although the hemorrhage may be evenly distributed throughout the vitreous or focal. Long-standing preretinal hemorrhage may form a white mass.

Ultrasonography can be used to determine whether a retinal detachment is present and may also help determine the cause of the vitreous hemorrhage.

Q10. What are the causes of this condition?
Answer and interpretation

There are lots — but the first two are the most important ones:

  • diabetic retinopathy
  • retinal break or detachment
  • posterior vitreous detachment
  • ocular tumor
  • central or branch retinal vein occlusion aka CRVO or BRVO (associated with neovascularisation)
  • Terson syndrome in subarachnoid hmorrhage (e.g. subhyaloid hemorrhages)
  • Trauma
  • Sickle cell disease
  • age-related macular degeneration
  • retinal artery microaneurysm
  • Other rare causes like Eales disease

Q11. Describe the management of this condition.
Answer and interpretation
  • ophthalmology referral
  • bed rest with head elevation for ~3 days
  • avoid drugs that contribute to bleeding (e.g. anticoagulants, antiplatelet drugs)
  • screen for and treat underlying causes
  • retinal breaks are treated with cryotherapy or photocoagulation
  • vitrectomy may be required (e.g. retinal detachment, or persistent hemorrhage)



Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.