Vitreous and Retinal Detachment

describe the anatomy of the vitreous

Transparent gel

Water (98%), collagen, hyaluronan

Viscoelastic

Deforms and returns to original shape

Structural support

Shock-absorber

where is the strongest attachment in the back of the eye

Vitreous base

where are the looser attachments in the Vitreous-Retina

posteriorly

what is the vitreous base

ring-shaped attachment which extends around the ora serrata

At the vitreous base, it is the _____ ______ _______ which is attached around the ora serrata

anterior hyaloid membrane

where is the posterior vitreous cortex loosely attached to

inner limiting membrane of the retina

what is ageing associated with in Vitreous Degeneration

liquefaction of the vitreous; vitreous progressively transforms to become more fluid

what is vitreous syneresis

shrinkage of the vitreous

what does vitreous syneresis lead to

liberation of small collagen fibrils from the vitreous structure; these collagen fibrils then aggregate to form strands which ‘float’ within the liquefied vitreous

what does Liberation of collagen fibril strands form

floaters

Degeneration of vitreous degeneration is accelerated in?

myopic patients

what is Healthy degeneration of vitreous

bilateral, gradual, long-standing floaters

what is Posterior Vitreous Detachment

Detachment of posterior hyaloid membrane from retina

what still remains intact during a Posterior Vitreous Detachment

attachment between the anterior hyaloid membrane and the ora serrata typically remains intact

what does Vitreous degeneration causes vitreous to

collapse anteriorly

what is the underlying cause of a PVD

vitreous degeneration: syneresis (shrinkage) and synchysis (liquefaction)

what does degeneration of PVD place tension upon

the weak attachments between the posterior vitreous and the retina: the vitreo-retinal interface

what is vitreoretinal dehiscence

separation of vitreous from retina which allows the vitreous to collapse inwardly toward the centre of the globe- away from the retina

describe the time period that a PVD occurs in

slowly, over the course of several months

where do PVD’s often start

at macula

how would an advanced PVD be described

Detachment from optic nerve head

why does a Weiss ring occur

Detachment of the vitreous from the optic nerve head

describe anomalous PVD

• Residual vitreous-retinal adherence

• Vitreo-retinal traction

• Retinal tears

name 4 risk factors of PVD

1. age

2. myopia

3. female

4. cataract surgery

symptoms of Posterior Vitreous Detachment

Painless

Usually unilateral (both eyes eventually involved)

Sudden onset symptoms

Many are asymptomatic

Flashing Lights (Photopsia)

Floaters

what are the signs of a Posterior Vitreous Detachment

Dilated, indirect ophthalmoscopy

Posterior vitreous floaters- pull joystick back

Weiss ring

Detached posterior vitreous

Vitreous Haemorrhage

describe the Vitreous Haemorrhage found in PVD

• Strong attachments over retinal blood vessels, due to thin inner limiting membrane

• Tension placed on strong attachments; tension tears retinal blood vessel- haemorrhage

A vitreous haemorrhage may cause the patient to report symptoms oF

sudden shower of small, dark floaters (red mist)

management of PVD

benign, require no treatment

Examine carefully for retinal break/tear or detachment

for the management of PVD, when would patients be asked to attend A&E?

➢ Increase in floaters

➢ Flashing lights

➢ Curtains/shadows developing over their vision

when would we review the patient with a further dilated fundus examination

6 weeks time

what should we provide the px with, during the management of a PVD

written information about the symptoms of retinal detachment

when would an emergency referral be made for a PVD

PVD complicated by a vitreous haemorrhage

what is the most common retinal detachment

Rhegmatogenous Retinal Detachment

why does a Rhegmatogenous Retinal Detachment occur

formation of a break in the retinal tissue

what does Rhegmatogenous Retinal Detachment lead to

influx of vitreous fluid into the area directly underneath the retina

what does the sub-retinal fluid separate

the retina from the underlying retinal pigment epithelium (RPE)

why does a rhegmatogenous detachment tend occur

the smooth, continuous retinal tissue is perforated by a break; often caused by PVD

why does a PVD cause perforation of a break

tension between the detaching posterior vitreous and the inner limiting membrane

what treatment can be done to protect against development of break

prophylactic treatment of a retinal break (tear/hole) with laser or cryotherapy (to burn or freeze retinal tissue)

Once a break in the retinal tissue has been made, fluid from the degenerated vitreous can flood into ______?

the sub-retinal space

where does fluid accumulate in Rhegmatogenous Retinal Detachment

sub retinal space; photoreceptors and RPE

what are the risk factors of Rhegmatogenous Retinal Detachment

1. PVD

2. age

3. myopia

4. ocular trauma

what are symptoms of Rhegmatogenous Retinal Detachment

Flashing Lights (Photopsia)

Floaters

Curtain, Veil or Shadow

what are signs of Rhegmatogenous Retinal Detachment

VA

IOP (modest reduction (≈5mmHg))

Pupils (RAPD)

Visual fields

Anterior vitreous (tobacco dust or Shafer’s sign)

what causes the tobacco dust in Rhegmatogenous Retinal Detachment

release of RPE cells into the vitreous

describe the appearance of tobacco dust

small, dark brown cells in the anterior vitreous

what are the most common types of breaks found in Rhegmatogenous Retinal Detachment

‘U’ or ‘horseshoe’

what is a operculated tear

rather than simply being ripped, a round segment has been completely torn from the rest of the retina, leaving a distinct hole

Retinal breaks are initially ____?

flat

why does Oedema occur

vitreous fluid flowing through the break into the sub-retinal space

As the sub-retinal fluid accumulates, the retinal break smoothly transforms into a _____ ______?

retinal detachment

what would require an emergency referral for retinal breaks

• Vitreous haemorrhage

• Positive Shafer’s sign/tobacco dust (i.e. RPE cells in the anterior vitreous)

• Retinal break, tear or hole

• Retinal detachment

what would confirm diagnosis of uncomplicated PVD diagnosis

• The patient’s symptoms of flashing lights have resolved, and the floaters have become stable

• Vision is normal • We have located a Weiss ring floater

• There is no tobacco dust in the anterior vitreous/Shafer’s sign is negative

• A dilated fundus exam has reveal no sign of a vitreous haemorrhage

• A dilated fundus exam has revealed no sign of a retinal break

what conditions is Tractional Retinal Detachment usually associated with

advanced diabetic retinopathy retinal vein occlusions

Tractional Retinal Detachment is associated with?

retinal isachaemia; lack of oxygenated blood supply to the retina

what does Lack of oxygen supply trigger in Tractional Retinal Detachment

neovascularisation

what is neovascularisation

development of very fine, thread-like new blood vessels which are intended to restore the supply of oxygenated blood to the deprived retinal region

why is neovascularisation bad

fragile and prone to leakage (haemorrhaging)

what does the body produce In order to support the new blood vessels in neovascularisation

fibrovascular membrane

describe where the Fibrovascular membrane extends from

retina into vitreous

fibrovascular membrane then contracts which creates?

tension between the vitreous and retina

why does tractional retinal detachments occur

This fibrovascular membrane extends from the retina, into the vitreous and attaches to the gel. The fibrovascular membrane then contracts which creates tension between the vitreous and retina. This tension pulls the retina away from its attachment, creating a tractional retinal detachment.

Tractional retinal detachments develop more _______ than rhegmatogenous detachments.

gradually

what symptoms may patients experience during tractional detachments

curtain/veil or shadow

what does tractional retinal detachments not feature?

retinal break or tear; therefore no no tobacco dust

= Shafer’s sign is negative

why is there no tobacco dust in tractitional detachment

there is no route for RPE cells to reach the anterior vitreous

what is Exudative Retinal Detachment

accumulation of fluid underneath the retina

what sort of swelling is present in Exudative Retinal Detachment

dome-like swelling

what causes the sub retinal fluid in Exudative Retinal Detachment

• Posterior uveitis

• Posterior scleritis

• Inter-ocular or retro-bulbar tumours

what does Exudative Retinal Detachment seperate

Separates retina from underlying RPE

what is not present in Exudative Retinal Detachment

• No retinal break/tear

• No tobacco dust/Negative Shafer’s sign

• No symptoms of photopsia

• No floaters, unless posterior uveitis (vitritis)