L Vitreoretinal disease Flashcards
What is PVD?
separation of cortical vitreous from neurosensory retina
What can vitreous detachment lead to
Damage to blood vessel = haemorrhage
Retinal hole
Retinal tear
What is vitreous syneresis?
What is vitreous?
What are the symptoms of a PVD?
- Flashes
- floaters
3.black dots/shadow
4.black strand/spider webs.
What do flashes and floaters look like for someone with PVD?
flashes=Fraction of a second
Usually occurs on eye movement Usually perceived in dim light
floaters= Continues to move after eye comes to a rest
What are the causes of flashes?
Posterior vitreous detachment
Retinal tear / detachment Retinal Vasospasm
Migraines
Occipital Lobe lesions
History of vitreoretinal surgery
Inflammations
What are the causes of floaters?
Vitreous syneresis
Posterior vitreous detachment
Vitreous Haemorrhage
Retinal tear / detachment
Intermediate & Posterior uveitis Tumours
Asteroid Hyalosis (occasionally)
exact cause of flashes?
The vitreous pulling on the retina
What is the exact cause of floaters?
Collagen strands are present in vitreous
After vitreous liquefaction, gel pockets occur and collagen strands thicken.
Vitreous liquid allows more movement of strands
vitreous opacities cast shadow on retina
How does the vitreous change with age?
- gel shrinks amd pockets of fluid (from gel form)
- thick collagen strands in the vitreous
- pockets of fluid converge to create larger pocket s
- increases mobility of vitreous
- vitreous still remains attached (at ora errata, ONH , blood vessels)
weiss ring
-ring of cortex around ONH
-If it becomes removed, it may be seen as an annular (ring-shaped) floater
-sign vitreous has separated from retina
What does Weiss ring lead to?
Liquefied vitreous can build up behind the gel and move behind the retina if a tear occurs
This can lead to a retinal detachment
How is the ora seratta affected if there is a retinal detachment ?
if RD occurs it will not extend beyond the ora seratta
Sub retinal fluid cannot t spread forwards.
difficult to view retina at this point-= so scleral indentation during head mounted indirect ophthalmoscopy required
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