Vitreous Flashcards
how much % of the eye does the vitreous occupy
80%
where is the vitreous most strongest
at the vitreous base, which is a circumferential band from posterior plans plan to a few mm behind the ora serrata
where is the vitreous loosely attached
most loosely attached to the retina
which three things is the vitreous most strongly attached to
most strongly attached at the:
- optic disc/ONH around annulus of zinn
- macula
- along retinal blood vessels
what are three symptoms associated with the vitreous
- floaters
- vision
- flashes
what is floaters and what symptoms can they cause
compressed cells or strands of the vitreous clumped together, so they are less transparent than the rest. some are harmless remnants of the hyaloid artery.
symtoms is may be a bit annoying and rarely interfere with activities
what are the treatments for floaters
on the whole there is no treatment, or you can do:
- victrectomy - take the vitreous out, but is rare as can tear retina as well
- laser vitreolysis - is risky and rarely justified, this dissolves vitreous floaters
what is floaters and what symptoms can they cause
compressed cells or strands of the vitreous clumped together, so they are less transparent than the rest. some are harmless remnants of the hyaloid artery.
symtoms is may be a bit annoying and rarely interfere with activities, only reduces vision is floaters are very numerous i.e. significant amount
what causes flashes
photopsia from traction of the vitreous on the retina & not from the vitreous itself
retina has no pain receptors so it flashes light instead
what are the three types of cells that can be found in the vitreous
- leucocytes (white BC)
- erythrocytes (red BC)
- pigment cells in anterior vitreous
what are leucocytes in the vitreous indicative of
inflammation
what are the four types of cells that can be found in the vitreous
- leucocytes (white BC)
- erythrocytes (red BC)
- pigment cells in anterior vitreous
- tumour cells
what are leucocytes in the vitreous indicative of
inflammation
where can tumours in the vitreous come from
an intra ocular tumour such as melanoma or retinal blastoma
what are white cells in the vitreous
either inflammatory or denatured (old) red blood cells
what are white cells in the vitreous a sign of
- intermediate uveitis (pars planitis) or posterior uveitis
- inflammatory disease of the posterior segment
- anterior uveitis which can lead to a ‘spill over’ of cells into the anterior vitreous
what can stay in the vitreous for a very long time
inflammatory cells so doesn’t mean its active inflammation if you see white cells, it may just mean they had inflammation in the past
what is the vitreous very useful for
a convenient place for posterior segment drug delivery via the pars plana, the vitreous represents an inert depot location that holds the drug for medium term drug release
which three drugs and what are they for, can be injected into the vitreous as an inert depot that holds it
- anti-VEGF: for AMD to treat new blood vessels
- triamcinolone: steroids, which treats macula oedema or uveitis that doesn’t respond to other drug treatments
- methotrexate: autoimmune drug to treat macula oedema
what do red cells in the vitreous represent
vitreous haemorrhage (bleeding somewhere)
name 4 potential causes of red cells in the vitreous
- PVD with traction along a retinal blood vessel
- Retinal tear involving a retinal blood vessel
- proliferative retinopathy from diabetes or other neovascularising cause of ocular ischaemia (e.g. central retinal vein occlusion), causing new blood vessels
- breakthrough bleeding from a choroidal neovascular membrane or retinal macro aneurysm
what symptoms can a vitreous haemorrhage cause
obstruct vision
what can vitreous haemorrhage cause
can lead to fibrosis within the vitreous and can also cause a vitreous detachment
what is the appearance of pigment in the vitreous
pigment cells are, larger, darker and more irregularly shaped than red blood cells
