Posterior Vitreous Detachment

Question 1

Describe a PVD:

Answer 1

It’s a separation of vitreous from the sensory retina

Question 2

Where does the PVD occur?

Answer 2

It occurs posterior to the vitreous base

Question 3

What specifically detaches in a PVD?

Answer 3

The posterior hyaloid membrane detaches from the retina

Question 4

What does the posterior hyaloid membrane line?

Answer 4

The surface of the retina from the vitreous base back to the optic nerve

Question 5

In a PVD, which attachments are intact?

Answer 5

The attachment between the anterior hyaloid and the ora serata (vitreous base attachments)

Question 6

What is the actual cause of PVD?

Answer 6

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

Question 7

What does weakening of the attachments cause (besides a PVD 😬)

Answer 7

It leads to vitreo retinal dehiscience which is a separation of vitreous from the retina which allows the vitreous to collapse in

Question 8

What will happen if a hole develops in the cortex?

Answer 8

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

Question 9

Where do PVD’s start and what are they referred to as?

Answer 9

In the macula area and they are called partial detachments

Question 10

Explain the development of a posterior vitreous detachment

Answer 10

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

Question 11

Where does the detachment occur?

Answer 11

Inward to the globe

Question 12

In a PVD, which attachments survive the longest?

Answer 12

The attachments between the posterior vitreous and the optic nerve head

Question 13

What indicates when a PVD is complete?

Answer 13

Detachment of the vitreous from the optic nerve head

Question 14

For PVD, will all the attachments become ruptured?

Answer 14

No, the ones at the vitreous base will survive because they’re the strongest

Question 15

What gives rise to a Weiss ring?

Answer 15

Detachment of the vitreous from the optic nerve head

Question 16

Summarise the PVD process:

Answer 16

Youth= gel vitreous and vit/retinal adhesion – liquefaction without vitret dehiscience – anomalous PVD

Ageing= liquefaction and vitret dehiscience–complete PVD floaters

Question 17

Explain anomalous PVD:

Answer 17

Degenerative changes occur without dehiscence (seperation of vitreous and retina). This then leads to residual adherence between the vitreous and retina. Making eye movements causes the adherences to come under strain due to increased mobility of the vitreous. These adherences will then detach.

Question 18

What can anomalous PVD lead to?

Answer 18

Vitreoretinal traction which can lead to tears, holes and epiretinal membranes

Question 19

Name risk factors of PVD:

Answer 19

Age. 8% 40-50 years
44% 60-70
86% 80-90.
No PVDs in younger than 40 patients

Myopia: 29% 40-50 and myopia increases the risk by 4-5x but also depends on the magnitude of myopia. More myopic= increased risk

Females: more at risk by 2-3x

Trauma: increases the risk. Cataract surgery especially. 58.6% got PVD within 1 year. They can develop immediately and there can be longer delays

Question 20

Why does myopia increase the risk of PVD?

Answer 20

Because of myopic elongation and the attachments at more risk than normal patients

Question 21

Explain the symptoms of PVD

Answer 21

It’s associated with flashing lights and floaters. Flashes are more noticeable in dim lights and in the temporal field and are thought to be caused by tugging on the sensory retina. Floaters are described as cobwebs or threads or flies and move with the eye and are more noticeable under bright and plain backgrounds. Weiss ring will show up as a large circular floater

Question 22

Besides PVD and she related loss of vitreal transparency, what else causes floaters?

Answer 22

Vitreous haemorrhages or posterior uveitis.

Question 23

Why are floaters an issue?

Answer 23

Because they’re a nuisance and reduce the impact on the quality of life

Question 24

Why did floaters impact the quality of life for patients?

Answer 24

Because they cause a reduction in CS and images appear washed out

Question 25

How do we assess the fundus that has a PVD?

Answer 25

With dilation

Question 26

Does a Weiss ring indicate that PVD is incomplete?

Answer 26

No because it doesn’t always form and could be destroyed during detachment or adhesions at the macula persist beyond the onh

Question 27

When detached, where does the vitreous move?

Answer 27

It moves and pushes more anterior

Question 28

What appearance does the detached vitreous have?

Answer 28

Crumpled milky white transparent appearance

Question 29

What’s the most visible portion of the detached vitreous?

Answer 29

Posterior hyaloid membrane

Question 30

The space occupied by the vitreous (behind the posterior hyaloid membrane) how does this appear?

Answer 30

Optically clear