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Stage 1 Visit 2 > Competency 6.1.12 > Flashcards

Competency 6.1.12 Flashcards

1
Q

Physiological Sites of Vitreous Attachment

A
  • The vitreous is loosely attached to the inner limiting membrane of the retina
  • Stronger sites of vitreo-retinal adhesion are at:
    • Vitreous base (very strong)
    • Optic disc margins (fairly strong)
    • Perifoveal (fairly weak)
    • Peripheral Blood vessels (usually weak)
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2
Q

Pathological Sites of Vitreous Attachment

A
  • Lattice degeneration
  • Vitreomacular traction
  • Retinal neovascular vessels e.g. in DR
  • Snailtrack degeneration
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3
Q

What is Lattice Degeneration?

A
  • is a thinning of the retina that happens over time
  • most with this condition never have any symptoms or a loss in vision
  • prevalent in around 8% of the population however it is found in around 40% of those who have had a retinal detachment
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4
Q

How does Lattice Degeneration Cause Retinal Detachment?

A
  • Lattice degeneration causes a RD by premature PVD and tractional tears.
  • The vitreous overlying an area of lattice degeneration are synchytic however the attachments either side of this area are stronger than usual.
  • Tears may develop after a PVD in the area affected by lattice degeneration
  • Atrophic holes may lead to RD
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5
Q

What is Retinoschisis?

A
  • degeneration of the peripheral retina which causes the retina to split into two different layers
  • split often occurs at the level of the outer plexiform layer
  • results in severing of neurons and therefore a complete loss of visual function in the affected area
  • present in around 5% of the population and is more common in hypermetropic patients
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6
Q

Retinoschisis Symptoms

A

It is often asymptomatic as it lack the vitreo-retinal traction required to cause flashes/floaters, even if the RS is located posterior to the equator the patient seldom notices a field defect.

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7
Q

Retinoschisis Signs

A
  • usually bilateral
  • typically begins by involving the extreme infero-temporal peripheral fundus.
  • appears as a smooth dome-shaped elevation of the retina
    o elevation is smooth and relatively immobile compared to the opaque and corrigated appearance of a rhegmatogenous RD
  • The lesion may progress until it has involved the entire circumference of the peripheral retina
    o The typical form usually stays out here
    o The reticular type is more likely to spread posteriorly
  • The presence of a pigmented demarcating line is likely to indicate RD rather than retinoschisis
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8
Q

What is a Posterior Vitreous Detachment?

A
  • separation of the vitreous body from its sites of attachment posteriot to the vitreous base
  • This occurs due to synchysis of the vitreous humour which forms small fluid filled cavities.
  • PVD is a normal age related event and PVD prevalence increases with age.
  • usually be a spontaneous event, it can be induced by the likes of surgery, trauma or uveitis
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9
Q

Posterior Vitreous Detachment Prevalence

A

Only around 10% of those inder 50 years of age have had a PVD however this is around 66% of those over 70 years.

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10
Q

How Often Does Posterior Vitreous Detachment lead to Retinal Detachment

A

Normally 10% of those with a symptomatic PVD will have suffered a retinal tear, however if there is a haemorrhage this rises to 60%.

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11
Q

The Usual Sequence of Events of a PVD

A
  • Perifoveal detachment
  • Foveal separation
  • Detachment from posterior retina as far as equator
  • Initially disc attachment may remain
  • Peripheral detachment as far as vitreous base (only attachment to remain)
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12
Q

Posterior Vitreous Detachment Symptoms

A
  • Flashes
    o Described as lightning arc-esq
    o Can be induced by eye or head movement
    o Mostly seen in temporal periphery
    o More noticeable in dim illumination
  • Floaters
    o Mobile vitreous opacities
    o Most evident against a bright pale background
    o Can be Weiss ring/vitreous blood
  • Blurred vision
    o Can be due to dispersed haemorrhage
    o Can be due to floaters on visual axis
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13
Q

Posterior Vitreous Detachment Signs

A
  • Posterior hyaloid membrane can sometimes be seen on posterior examination
  • Haemorrhage may be indicated by small red cells in the vitreous cavity
  • Weiss ring
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14
Q

What is a Retinal Break?

A
  • often occurs due to vitro-retinal traction at sites of adhesion, whether than be physiological or pathological
  • When there is a retinal break the vitreous fluid has access to the area behind the retina.
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15
Q

Retinal Break Prevalence

A

Retinal breaks occur in around 20% of eyes with a symptomatic PVD and belived to be around 8% of eyes in the general population

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16
Q

Retinal Break Timing

A
  • Usually present sooner after symptoms of a PVD
  • Tear formation can be delayed in rare cases
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17
Q

Retinal Break Location

A
  • Tears aossciated with a PVD usually located in upper retina
  • More often temporal than nasal
  • Macular breaks related to PVD are rare
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18
Q

Retinal Break Morphology

A
  • Retinal breaks may be flat or may have aossicated area of sub-retinal fluid
  • If there is more than 1 disc diameter of fluid form the edge of the break then this is defined as a retinal detachment
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19
Q

Types of Retinal Tears

A
  • Horseshoe Tears
  • Operculated Tears
  • Retinal Holes
  • Dialysis
  • Giant Retinal Tear
20
Q

Features of Horseshoe Tears

A

o Consists of a flap
o Its apex is pulled anteriorly by the vitreous
o Base remains attached to retina

21
Q

Features of Retinal Holes

A

o Round/oval
o Usually smaller than tears
o Lower risk of RD
- If RD occurs then is usally:
 slowly progressing
 in a young female myope
o PVD not necessarily present

21
Q

Features of Operculated Tears

A

o The flap is completely torn away by the vitreous leaving a round/oval break
o The patch of torn away retina can be seen in the vitrous cavity

22
Q

Features of Dialysis Retinal Detachment

A

o Circumferencial tear along ora-serrata
o Usually due to trauma
o Vitreous remains attached at posterior part of break
o Appears as large RD
o Slowly progressive in absence of PVD

23
Q

Features of Giant Retinal Tear

A

o Involving 90 degrees or more of retinal circumference
o Vitreous remains attached to anterior part of break (unlike dialysis)
o Most often located at immediately posterior to ora-serrata but can be at equator

24
Q

What is a Rhegmatogenous Retinal Detachment?

A
  • often characterised by a retinal break often due to vitreo-retinal traction
  • allows for liquified vitreous to travel under the retina which separates it from the RPE
  • A RD will almost never occur in this manner if the vitreous is not liquified and there is no traction.
25
Q

Rhegmatogenous Retinal Detachment Risk Factors

A
  • Myopic eyes
  • Vitreous degeneration
  • PVD
  • Lattice degeneration
  • Snailtrack degeneration
  • Vitreous loss during cataract surgery
26
Q

Distribution of Breaks in Rhegmatogenous Retinal Detachment

A
  • Where are Breaks located?
    o 60% superotemporal
    o 15% superonasal
    o 15% inferotemporal
    o 10% inferonasal
  • Multiple Breaks?
    o Half of eyes with retinal detachment have two holes
  • Often within the same quadrant
27
Q

Rhegmatogenous Retinal Detachment Symptoms

A
  • Flashes and floaters (due to PVD)
    o Location of photopsia is of no use in locating the primary break
  • Curtain-esq peripheral VF defect appears
    o Sometimes can resolve and not be present upon waking in the morning due to spontaneous absorption of SRF
    o The quadrant of VF affected will often be the oppose quadrant of the primary break
    o A lower VF defect if more often appreciated earlier by patient than a superior defect
  • Loss of central vision
    o Could indicate macular involvement
    o Or obstruction of visual axis of large detachment
28
Q

Rhegmatogenous Retinal Detachment Signs

A
  • RAPD
    o Present in eyes with extensive RD
  • IOP
    o Normally around 5mmHg lower than normal eye
    o If extremely low then a choroidal detachment could be present
    o Can be increased if there is Uveitis associated with trauma
  • Iritis
    o Usually mild
  • Tobacco Dust
    o Highly suggestive of retinal break
    o Pigment cells located in anterior vitreous
  • Blood cells or inflammatory cells are also highly specific
  • Retinal Breaks
  • Visible retinal detachment
29
Q

Appearance of a Fresh Rhegmatogenous Retinal Detachment

A
  • RD has a convex shape
  • Slightly opaque
  • corrugated appearance (due to retinal oedema)
  • Loss of underlying choroidal pattern
  • BVs appear darker than in flat retina
  • SRF extends up until ora-serrata (unless caused by macular hole)
  • Macular pseudohole
  • Will be quite mobile
30
Q

Appearance of a Longstanding Rhegmatogenous Retinal Detachment

A
  • Retinal thinning
    o Due to atrophy
  • Intraretinal Cysts
    o May develop if detachment has been present for about 1 year
  • Subretinal Demarcation Lines
    o Caused by proliferation of RPE cells at junction of flat and detached retina
    o Takes around 3 months to develop
    o Does not limit spread of SRF
31
Q

What is a Tractional Retinal Detachment?

A
  • Tractional RD is caused by contraction of fibrovascular membranes in areas of vitreo-retinal traction
  • PVD in eyes with DR is often incomplete and more gradual which is thought to be due to leakage of plasma into vitreous gel
  • If a break occurs in a tractional RD then it assumes the characteristics of a rhegmatogenous RD and progresses rapidly.
32
Q

Tractional Retinal Detachment Causes

A
  • Proliferative DR
  • Retinopathy of prematurity
  • Penetrating posterior segment trauma
33
Q

Tractional Retinal Detachment Symptoms

A
  • Flashes and floaters usually absent as not associated with an acute PVD
  • VF defect
    o Slowly developing over months of years
34
Q

Tractional Retinal Detachment Signs

A
  • RD has concave form
  • Breaks usually absent
  • Retinal mobility is severely reduced with no shifting fluid
  • Less expansion of SRF
  • Highest elevation occurs at site of traction
35
Q

What is an Exudative Retinal Detachment?

A
  • characterised by the accumulation of SRF in the absence of a retinal break or traction
  • often due to fluid leaking out of vessels out of vessels and accumulating under the retina.
  • If the RPE is able to cope and pump out the fluid into choroidal circulation then there is no RD
36
Q

Exudative Retinal Detachment Causes

A
  • Choroidal tumours
    o Intraocular tumour should be considered the cause of exudative RD until proven otherwise.
  • Inflammation (incl posterior scleritis)
  • Bullous central serous chorioretinopathy
  • Iatrogenic
  • Choroidal Neovacularisation
37
Q

Exudative Retinal Detachment Symptoms

A
  • no flashes as no vitreoretinal detachment
  • Floaters may be present only if there is associated vitritis
  • VF defect may develop suddenly and progress rapidly
38
Q

Exudative Retinal Detachment Symptoms

A
  • Convex profile
  • Surface is smooth and not corrugated
  • Very mobile
  • Shifting fluid detaches the area of retina where it is located
39
Q

What is Pneumatic Retinopexy?

A
  • Outpatient procedure
  • a bubble of gas alongside laser/cryotherapy is used to seal a rhegmatogenous RD
  • This procedure is usually reserved for the treatment of uncomplicated RD with a small retinal break in the peripheral retina.
40
Q

Advantages and Disadvantages of Pneumatic Retinopexy

A

Advantages:
- Quick
- Minimally invasive

Disadvantages:
- Success rated lower than conventional scleral buckling

41
Q

What is Scleral Buckling?

A

Is a surgical procedure where material sutured onto the sclera creates a buckle which aims to close retinal breaks by:
- placing the RPE next to the sensory retina
- Reduce dynamic vitreoretinal traction

42
Q

Complications of Scleral Buckling

A
  • Diplopia
    o Due to mechanical effect of buckle
    o Early spontaneous resolution is typical
  • CMO
    o Occurs in 25% but usually responds to treatment
    o Can also be epiretinal membrane
  • Anterior Segment Ischaemia
    o Due to vascular compromise
  • Infection
  • Elevated IOP
43
Q

Indications for a Vitrectomy

A
  • When retinal breaks cannot be visualised due to e.g haemorrhage or debris etc
    o Scleral buckling prognosis is poor if any breaks are missed
  • When retinal breaks are unlikely to be closed by scleral buckle alone
    o Giant tears
  • Tractional RD
  • Prevention of tractional retinal detachment
44
Q

Goals of a Vitrectomy

A
  • Separate the posterior hyaloid from retinal surface
  • To remove the epiretinal tissue to release retinal traction
  • Close retinal breaks if present
45
Q

Vitrectomy Complications

A
  • Intraoperatively
    o retinal breaks
    o choroidal haemorrhage
  • Postoperatively
    o Retinal breaks and rhegmatogenous RD
    o Retinal fold
    o Inflammation
    o Raised IOP
    o Cataract

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