Other / Other / MRI

Posterior vitreous detachment

Posterior vitreous detachment (PVD) is evaluated when patients present with sudden onset floaters or photopsia, particularly in older adults over 60 years where it is a common age-related condition occurring in over 70% of the population.

Key Images

Look For First

Linear, echogenic membrane in the posterior vitreous compartment that is freely mobile with eye movements
Characteristic exaggerated 'after movements' (persistence of motion after eye stops moving) more prominent than retinal detachment
Membrane crossing the optic nerve sheath-posterior globe wall intersection, distinguishing it from retinal/choroidal detachment

Key Image Findings

On ultrasound, PVD appears as a linear echogenic membrane within the posterior vitreous compartment
The membrane is freely mobile with oculokinetic ultrasonography, demonstrating pronounced 'after movements' in acute stages that persist longer than expected from retinal or choroidal detachments
The vitreous base represents the point of attachment of the hyaloid membrane and may demonstrate tethering near the ora serrata
Unlike retinal and choroidal detachments, the PVD membrane crosses the intersection of the optic nerve sheath and the posterior wall of the globe
Thickening of the membrane may be observed in the presence of associated hemorrhage or inflammation
Mobility of the detached hyaloid membrane may decrease over time, making differentiation from other vitreous pathologies more difficult in chronic cases
PVD may be associated with complications including retinal detachment, vitreous hemorrhage, and other posterior segment pathology

Differential Diagnosis

Retinal detachment: distinguished by fixed membrane that does not show prominent after movements and does not cross the optic nerve sheath
Choroidal detachment: identified by location in the choroidal space with characteristic appearance differing from vitreous membrane position
Vitreous hemorrhage: echogenic appearance without discrete membrane formation; typically more diffuse opacification
Asteroid hyalosis: multiple small echogenic foci throughout vitreous rather than single linear membrane; typically stable and non-mobile

Discussion

Posterior vitreous detachment is a normal age-related phenomenon occurring in over 70% of patients over 60 years and is the most common cause of acute floaters

The classic clinical presentation of floaters reflects vitreous condensations along the detached hyaloid membrane that cast shadows on the retina

Photopsia (flashing lights) occurs due to mechanical traction on the retina during eye movements

The prominent 'after movements' on ultrasound represent the fluid nature of the subhyaloid space and the freely mobile hyaloid membrane

While PVD is usually benign, it can be associated with serious complications including retinal tears, retinal detachment, and vitreous hemorrhage that require careful evaluation

Chronic PVD may lose its characteristic mobility, necessitating correlation with clinical presentation and careful differentiation from other posterior segment pathology

Reporting Pearls

Describe PVD as a "freely mobile linear echogenic membrane within the posterior vitreous compartment with prominent after movements, consistent with posterior vitreous detachment," and specifically note the relationship to the optic nerve and confirm absence of associated retinal detachment or hemorrhage.

Pitfalls

Mistaking the PVD membrane for retinal or choroidal detachment by failing to assess mobility and after movements; key distinguishing feature is the prominent persistent motion
Assuming immobile hyaloid membrane is retinal detachment without careful evaluation of membrane position and its relationship to globe wall landmarks
Overlooking associated complications such as retinal tears, retinal detachment, or vitreous hemorrhage that may require urgent clinical attention
Failing to correlate ultrasound findings with clinical presentation; acute symptomatic PVD should have prominent characteristic after movements whereas chronic PVD may have reduced mobility