DIS - Diseases of the Vitreous Humour I - Week 8 Flashcards by B H

Describe the vitreous humour (2).

A clear avascular and acellular gel

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What is the typical volume of the vitreous humour and what percent of it is water?

~4mL
99% H2O

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Describe the structure of the vitreous humour. What kind of strength is conferred with this structure?

Complex parallel structure of collagen fibres
Confers antero-posterior strength

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What are collagen fibres in the vitreous humour separated by and what is the significance of this?

Fibres separated by hyaluronic acid pockets, which contain water

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What is the main collagen matrix of the vitreous humour held in place by? What does this improve?

It is cross-linked by type 2 collagen
Improves lateral structure and strength

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What does the collagen matric of the vitreous humour provide a frame for? What does this act as and what does it attract? What is the outcome (2)?

Provides a frame for hyaluronic acid coils to anchor to
Coils act as a spring
Coils attract and bind water
-results in the formation of a gel to cushion the eye

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While the vitreous humour is relatively acellular, list 6 cells you could expect to find here.

Hyalocytes
RPE cells (fibroblasts)
Myo-fibroblasts
Astrocytes
Macrophages
White blood cells

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What is the vitreous humour surrounded by (aside from the retina) and what is it exactly? What is this fused with?

By a hyaloid membrane
-condensation of collagen IV fibres
-fused with the retinal internal limiting membrane

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Where are the strongest adhesions of the hyaloid membrane to the eye (4)? List in order starting with strongest.

Pars plana
ONH
Foveola
Retina (BV and other)

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Where is the vitreous base and how long is it?

3 to 4mm zone straddling pars plana and ora serrata

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List 6 functions of the vitreous humour.

Maintains eye shape and structural support
Sustains retinal apposition
Promotes optical clarity
Provides shock absorption
Prohibits migration of cells/blood
Inhibits neovascularisation

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What compound of the vitreous humour inhibits neovascularisation?

Opticin

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What is the tunica vasculosa lentis, what does it do, and when does it form?

A vascular sheath to the lens, supporting active lens growth
Forms 1 month in utero

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Where can the hyaloid artery be found and within what structure?

In cloquet’s canal within the tunica vasculosa lentis

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Describe how the tunica vasculosa lentis forms and degenerates and when.

As the hyaloid system atrophies near term, a secondary vitreous humour forms near the retina, surrounding and compressing the primary vitreous humour into the TVL, extending from the ONH to the lens
It degenerates with time by 1 month post-natal

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What are congenital abnormalities of the vitreous humour mostly due to?

Partial decay or remnants of the tunica vasculosa lentis

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List the three most commn tunica vasculosa lentis remnants and where they are found.

Mittendorf dot (lens)
Bergmeister’s papilla (ONH)
Perisistent primary hyperplasic vitreous humour

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Describe perisistent primary hyperplasic vitreous humour and what it encroaches on.

Thickened due to compression by secondary vitreous humour formation
Encroaches on the lens

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What is a mittendorf dot? Use the SOAP acronym.

Anterior remnant of the hyaloid artery
S - patients usually asymptomatic
O - opacity and condesation just below and nasal to the posterior pole
A - advise patient and build confidence
P - none required

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What slit lamp technique is best for mittendorf dots?

Best seen with red reflex, direct view for location

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What is bergmeister’s papilla? Use the SOAP acronym.

Posterior remnant of the hyaloid artery
S - asymptomatic
O - remnant of the hyaloid system
A - DFE, look for traction
P - advise patient

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How does bergmeister’s papilla look compared with a persistent hyaloid artery?

BP - solid mass of whitish tissue or delicate glial strands stretching over the disc
PHA - glia emanating from ONH towards lens

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What is persistent hyperplasic primary vitreous humour? Is it anterior or posterior? Is it serious or benign?

When the tunica vasculosa lentis persists and proliferates
Anterior (mostly) or posterior (rare)
-potentially very serious

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What are the signs of anterior persistent hyperplasic primary vitreous humour (3)?

Visual obstruction (amblyopia and strabismus)
Leukocoria (white pupil)
Fibrovascular proliferation behind the lens

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List three possible diseases secondary to anterior persistent hyperplasic primary vitreous humour.

Lens swelling/cataract 2° glaucoma 2° retinal detachment

What is posterior persistent hyperplasic primary vitreous humour often associated with (3)?

Retinopathy of prematurity Signs of retinal detachment Posterior uveitis/inflammation

List four objective signs of posterior persistent hyperplasic primary vitreous humour.

Fibrovascular proliferation on the disc/retina Traction on the retina/ONH from shrinkage (twisted disc appearance) Lens opacity 2° retinal detachment

List four differential diagnoses for persistent hyperplasic primary vitreous humour.

Retinoblastoma Retinopathy of prematurity Cataract Glaucoma

What is the management for persistent hyperplasic primary vitreous humour (4)?

Refer to an ophthalmologist Provision of aphakic Rx Manage amblyopia/BV Note milder cases in adults - monitor traction for RD

What is a vitreous cyst (2)?

Uncommon remnant of the hyaloid system or overgrowth of CB epithelium

List two signs of a vitreous cyst.

Persistent floater Visual disturbance

How does a vitrous cyst appear?

Vague spherical mass in the vitreous humour

List three differential diagnoses for vitreous cyst.

PVD Cells due to uveitis Traction

What is the management for vitreous cyst (3)?

Monitor symptoms -refer for vitrectomy or photocystotomy if problematic

What is syneresis?

Age-related liquefaction of the vitreous humour

Does syneresis occur sooner or later in myopes?

Sooner

Describe how syneresis occurs .

Involves the release of previously bound water which accumulates in lakes This is accompanied by a collapse of the gel structure and condensation of collagen into clumps or threads Lakes coalesce eventually

What gives most traction on the superior retina and where?

PVD at the blood vessels

What are lacunae?

Lkes of accumulated water with syneresis

What are three signs of syneresis?

Floaters from collagen condensations/water release Posterior vitreous detachment Traction/retinal detachment (flashes)

How does syneresis appear on slit lamp examination (2)?

Floaters appear as ghost veils Liquefaction (things swimming around)

What is the best method to assess syneresis?

OCT for PVD

What is the management for syneresis?

Advise and monitor

What are vitreous floaters?

Any object in the vitreous humour seen by the patient

When are vitreous floaters often seen?

Lying back and looking up into the sky

What are operculum?

Floater due to retinal tissue

List 7 things that can be a floater.

Cells Vitreous strands Retinal tissue Foreign bodies Calcium phosphate Cholesterol Amyloid

What are four important signs/symptoms (history) that should be looked for if a patient presents with floaters?

Photopsia Distortion Trauma GH issues

List four differential diagnoses for vitreous floaters.

PVD Retinal detachment/tears Haemorrhage asteroid hyalosis Synchisis scintillans

Define posterior vitreous detachment.

Separation of the cortical vitreous from the ILM

Is posterior vitreous detachment more or less common in women vs men?

More common in women

Do lacunae form superiorly or inferiorly with syneresis and why is this so?

Usually superior due to gravity

What are two patient signs of posterior vitreous detachment?

A large central floater (ring shape) Photospia

What are three things that may be found on a fundus exam for posterior vitreous detachment?

Peri-papillary large oval or partly oval floater - overlies disc Hyaloid face well forward of the retina Small pre-retinal or vitreal haemorrhage -possible white retina due to traction

How should psoterior vitreous detachment be worked up during history and what three additional conditions should be considered?

Comprehensive history on recent floaters and photopsia Consider GH (diabetes), eye trauma, and inflammatory conditions

What should you look ofr on a slit lamp exam of posterior vitreous detachment?

Vitreous face

What should you do in the absence of a floater in a case of suspected posterior vitreous detachment?

OCT

What four things can photopsia from posterior vitreous detachment indicate?

Retinal tear RD from secondary retinal hole Macular hole Retinal or vitreous haemorrhage

What is the management for posterior vitreous detachment? Include review schedule.

Educate patient to return if worse Follow up after 2/12

When should posterior vitreous detachment be referred (4)?

If it is recent and has resulted in -visible retinal tears/tobacco dust -persistent unexplained photopsia -vitreous haemorrhage

Does photopsia with posterior vitreous detachment tend to subside over time or get worse?

Will eventually subside

What is asteroid hyalosis?

Lipids ebedded in a calcium phosphate matrix attached to the collagen framework

How does asteroid hyalosis appear?

Yellow/white specks that move with the framework but come back to the original position (sway)

True or false Asteroid hyalosis is never found in eyes with posterior vitreous detachment

True

Is asteroid hyalosis common more in young or older patients?

Older

Is asteroid hyalosis typically uni- or bilateral? Are patients symptomatic?

Often unilateral and asymptomatic

List four conditions which have a suggested association with asteroid hyalosis.

Diabetes/glucose intolerance Hypertnesion Atherosclerosis Hyperopia

Does asteroid hyalosis have any effect on vision?

Minor to none

What is the treatment for asteroid hyalosis?

None

What should be done if a patient have GH issues in addition to asteroid hyalosis?

Refer to GP for a workup

True or false Synchisis scintillans is never found in eyes with posterior vitreous detachment

False It is only found in eyes with posterior vitreous detachment

What is synchisis scintillans?

Cholesterol crystals that form in a liquid vitreous humour

When does synchisis scintillans appear in the vision and what happens after and why?

Appears with eye movement and sinks due to gravity

Is synchisis scintillans typically uni- or bilateral?

Bilateral

When does synchisis scintillans tend to occur?

In younger patients after PVD

What three conditions is synchisis scintillans associated with?

Advanced eye disease Chronic vitreous haemorrhage Trauma

What is the management for synchisis scintillans?

None, but monitor underlying eye condition and possible glaucoma