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Introduction to Eye Disease - Year 2 > Vitreous > Flashcards

Vitreous Flashcards

1
Q

What does the vitreous consist of and what is its composition?

A

•Consists of collagen, soluble proteins, hyaluronic acid and water

–98% water + 2% structural macromolecules

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2
Q

How is vitreous humour ‘attached’ to the eye?

A

It has a strong ‘attachement’ at the vitreous base - i.e. a circumfrential band from posterior plars plana to a few milimeters behind the ora serrata.

It also has tight adhesions to the optic disc, macula and retinal blood vessels as well as the inner limiting membrane.

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3
Q

What are functions of Vitreous humour?

A

To provide structural support to the globe.

To be transparent in order to let light through to the retina.

Posterior segment drug delivery via the pars plana (basically it is good for drug delivery as it is inert and so can hold a drug for a long period of time for medium/slow drug release)

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4
Q

When may the vitreous humour be used for drug delivery?

A

In the following cases:

–anti-VEGF drug delivery in cases of AMD and chemotherapy for intraocular tumours

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5
Q

What are floaters?

A

Floaters (sceintific name: muscae volitantes)

  • Most floaters are compressed cells or strands of vitreous clumped together so they are less transparent than the rest of the vitreous.
  • These are Probably embryological remnants (hyaloid artery)
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6
Q

What is the entopic phenomenon?

A

When floaters cast a shadow on the retina

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7
Q

How do floaters affect px vision?

A
  • Vision rarely affected unless floaters are numerous eg in posterior vitreous detachment (PVD)
  • Px may find floaters annoying but they rarely interfere with activities
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8
Q

What is the treatment for floaters?

A

•On the whole there is no treatment.

[Surgery or laser vitreolysis is risky and rarely justified]

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9
Q

How do we examine the vitreous via a slit lamp?

A
  • Narrow slit-beam, small angle between observation and illumination
  • Moderate magnification ~ 15-24x
  • Ask the patient to make rapid saccades (rapid eye movements in different directions)
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10
Q

What are general signs of vitreous disorders?

A

Cells in Vitreous

Pigment Cells in Vitreous

Vitreous Haemorrhage

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11
Q

What are ‘cells in the vitreous’?

A

Either denatured (old) red blood cells or leucocytes (white) blood cells

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12
Q

Why may cells in the vitreous be present?

A

–inflammation eg uveitis (intermediate or posterior or pan)

–Inflammatory cells stay in the vitreous for a very long time so may be new or old

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13
Q

True or false- Anterior uveitis can also lead to “spillover” of cells into the anterior vitreous

A

True

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14
Q

What clincal procedure must you do if you see cells in the vitreous?

A

Dilated Fundus Examination via Slit Lamp

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15
Q

What is the anterior vitreous and the posterior vitreous?

A

The anterior vitreous is basically just behind the lens and the posterior vitreous is just before the retina.

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16
Q

What is Schaffer’s sign?

A

Pigment cells in the Anterior Vitreous

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17
Q

How can we tell the difference between pigment cells and red blood cells in the vitreous?

A

Pigment cells are larger and less regular than red blood cells

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18
Q

What clinical procedure must you do if you see pigment cells in the vitreous?

A

Dilated fundus Examination (DFE)

19
Q

How do pigment cells in the vitreous arise?

A

They are as a result of macrophages containing pigmented RPE cells that have gained access to vitreous via a tear in neurosensory retina.

20
Q

What are potential causes of a Vitreous Haemorrhage?

A
  • Posterior Vitreous Detachment (PVD) with traction along a retinal blood vessel
  • A Retinal tear involving a retinal blood vessel
  • Proliferative retinopathy eg diabetic,vein occlusion or other neovascularising cause of ocular ischaemia
  • Breakthrough bleeding from a choroidal neovascular membrane or retinal microaneurysm
  • Trauma
  • And more….
21
Q

Whta clincal procedure must you undertake if you see a Vitreous haemorrhage?

A

Dilated Fundus Examination SL Biomicroscopy (DFE SL BIO)

22
Q

What does a vitreous haemorrhage tend to look like?

A

A ‘boat shaped haemorrhage’

That tends to sit towards the bottom due to gravity.

It sits in the pre-retinal space and so obscures the retina (i.e. it would block the view of retinal blood vessels)

23
Q

What are symptoms associated with a vitreous haemorrhage?

A
  • Sudden onset of floaters
  • A Mild bleed results in:
  • blurred vision (diffuse), but VA maybe unaffected

•A Severe/dense bleed results in:

  • reduced VA
24
Q

What is the treatment of a Vitreous Haemorrhage?

A
  • Treatment depends on severity and cause (e.g. in diabetic retinopathy you would want to manage the diabetes too)
  • May require vitrectomy
25
Q

What is Asteroid Hyalosis and how can we identify it?

A
  • It is a Common degenerative condition
  • Whereby there are Small, yellow-white opacities in the vitreous - these are calcium phosphate and lipid deposits
  • These Move with eye movements, but do not settle when eye is immobile (so stay suspended in the vitreous)
26
Q

What condition is Asteroid Hyalosis possibly asspciated with?

A

Diabetes

27
Q

True or False- Asteroid Hyalosis is more common in females than men

A

False- It is more common in men

28
Q

True or False- Prevalence to Asteroid Hyalosis increases with age

A

True

29
Q

True or False- Asteroid Hyalosis is a mainly bilateral condition

A

False- It is a unilateral condition 75% of the time

30
Q

What are symptoms of Asteroid Hyalosis?

A

Usually Asymptomatic

VA is rarely affected

31
Q

How may Asteroid Hyalosis affect fundus examination?

A

They may impair visualisation of the fundus by the optometrist (basically they block the view).

32
Q

What is the optometric management of Asteroid Hyalosis?

A

None (You just want to record its presence on px notes).

33
Q

What is Synchysis Scintillans?

A

A condition in which cholesterol conditions are present in the vitreous humour.

34
Q

What do cholesterold crystals in Synchysis Scintillans arise as a result of and how do they settle in the eye?

A

They arise from extravascular blood and so are normally the result of chronic vitreous haemorrhages.

These cholesterol crystals which are golden brown in colour, move within liquefied vitreous and settle inferiorly when the eye is immobile

[These cholesterol crystals may also be present in the anterior chamber]

35
Q

What may be underlying causes of Synchysis Scintillans?

A

–severe trauma

–chronic intraocular haemorrhage

–severe inflammation

–chronic retinal detachment

36
Q

What clincial technique would you do if you encountered Synchysis Scintillans?

A

Dilated Fundus Examination (DFE SL BIO)

37
Q

What is bergmeister papilla and how does it affect vision?

A

Remnants of the hyaloid artery seen as tuft on the Optic Disc

It doesn’t affect vision

38
Q

What is persistent hyperplastic primary vitreous?

A

When a px has a very obvious/distinct bergmeister papilla and Mittendorf dot. We call this a persistent hyperplastic primary vitreous

39
Q

What is Posterior Vitreous Detachment (PVD) and why does it occur?

A
  • It is the Separation of vitreous from neurosensory retina
  • Due to liquefaction (synchesis) of vitreous gel with age
  • This creates pockets of fluid filled cavities, which condense (syneresis) so that the liquid part of the vitreous sits pre-retinally and pushes the gel forward
40
Q

Will a patient know they have had a PVD?

A
  • No as it is Often spontaneous, without any adverse effects
  • ~25% will have complications e.g. retinal break that will require treatment
41
Q

What are possible symptoms of Posterior Vitreous Detachment (PVD)?

A

•Photopsia (flashes of light)

–Temporal

–More noticeable in dim light

–Momentary flashes

•Floaters

–Described by patient as spots/cobwebs/flies

–But…these may be present without a PVD

•Blurred vision/haziness may be reported if floaters on visual axis

42
Q

What are signs of a Posterior Vitreous Detachment (PVD)?

A
43
Q

What are possible complications of a Posterior Vitreous Detachment (PVD)?

A
44
Q

How may a Posterior Vitreous Detachment (PVD) result in a retinal detachment?

A

At an area of abnormal vitreoretinal adhesion, pressure exerted by the detached vitreous gel may cause a tear or break in the retina,this allows vitreous liquid to pass into subretinal space causing a Rhegmatogenous Retinal Detachment.

Introduction to Eye Disease - Year 2 (40 decks)

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