Posterior Vitreous Detachment Flashcards
Describe a PVD:
It’s a separation of vitreous from the sensory retina
Where does the PVD occur?
It occurs posterior to the vitreous base
What specifically detaches in a PVD?
The posterior hyaloid membrane detaches from the retina
What does the posterior hyaloid membrane line?
The surface of the retina from the vitreous base back to the optic nerve
In a PVD, which attachments are intact?
The attachment between the anterior hyaloid and the ora serata (vitreous base attachments)
What is the actual cause of PVD?
It’s caused by degeneration. Synchysis and synersis which cause tension on the weak attachments between the post vitreous and the retina. In the youth they’re strong but progressively weaken over time
What does weakening of the attachments cause (besides a PVD 😬)
It leads to vitreo retinal dehiscience which is a separation of vitreous from the retina which allows the vitreous to collapse in
What will happen if a hole develops in the cortex?
It allows the fluid (due to synchysis) to leak in the space between the inner limiting membrane and the posterior vitreous which is the retrovitreous space and this then causes an enlargement of the retrovitreous space and catalyses the detachment of vitreous from retina
Where do PVD’s start and what are they referred to as?
In the macula area and they are called partial detachments
Explain the development of a posterior vitreous detachment
1-in tact vitreous
2- small detachment temporal to the macula
3- detachment progressed and only fovea is attached
4-vitreous is close to complete detachment but an attachment in the middle of the fovea occurs
5- the fovea pit disappears as the vitreous pulls the fovea up
6-vitreous is fully detached from the macula but remains attached at the ONH
Where does the detachment occur?
Inward to the globe
In a PVD, which attachments survive the longest?
The attachments between the posterior vitreous and the optic nerve head
What indicates when a PVD is complete?
Detachment of the vitreous from the optic nerve head
For PVD, will all the attachments become ruptured?
No, the ones at the vitreous base will survive because they’re the strongest
What gives rise to a Weiss ring?
Detachment of the vitreous from the optic nerve head