Flashing And Floating

• Posterior vitreous detachment
• vitreous haemorrhage
• retinal break
• retinal detachment
• retinal hemorrhage

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.

History:

• 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).

Examination:

• 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.

About 10%

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

• past ocular surgery
• previous retinal tear
• family history
• ‘‘curtain coming down’
• high myopia

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
  

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.

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.

History:

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

Examination:

• 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.

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

• 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)

• LITFL Top 100 Ultrasound – Case 28 Vitreous haemorrhage
• LITFL Top 100 Ultrasound – Case 38 Retinal detachment
• Ehlers JP, Shah CP, Fenton GL, Hoskins EN. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease Lippincott Williams & Wilkins
• NSW Statewide Opthalmology Service. Eye Emergency Manual — An illustrated Guide. [Free PDF]