Retina And Vitreous Flashcards
What is the vitreous made up of?
- Water (98%)
- Collegen
- Hyaluronan
- Combo of other materials
Whats another name for the vitreous core?
Vitreous cortex and hyaloid membrane
4 facts about the vitreous
Its the bulk of the globe
Provides structural support
Shock obsorber
Visoelastic
What are the vitreous attachment and their order of strongest attachment?
- Vit base (strongest)
- Post Lens
- Optic Disc
- Macula
- Vessels
What is the function of the hyaloid artery?
Connects blood supply of optic nerve and anterior eye
What is pointed at here?
The hyaloid canal or cloquets canal
What 2 aspects are being pointed at here?
Top arrow: Mittendorf dot
Bottom arrow: hyaloid artery
Whats another name for a persistent hyaloid artery?
A bergmeister papilla
What are the potential signs symptoms that can arise with a mittendorf dot?
Signs: Circular opacity attached to posterior lens. Similar to PSC
Sxs: No sxs, may have reduced VA if close to visual axis
What happens to the vitreous with age?
Liquefaction process- becomes less gel more fluid
Shrinkage process- liberation of small collegen fibrils from vit
What is the shrinkage and liquefaction called?
Liquefaction= Synchesis Shrinkage= Syneresis
When are fibril floater most visible?
Bright and plain background
What are signs of a healthy vitreous degeneration
Gradual onset
Longstanding
Bilateral
What part of the vitreous detaches from the retina?
Posterior hyaloid membrane
What aspect remains intact in PVD?
Anterior hyaloid membrane and ora serrata
What is vitreous ret dehiscence and causes it?
Seperation of vitreous from reti a allowing vit to collapse centripetal
Cause: weakening of vitreous ret interface with age
What will catalyse the detachment?
Perforation which allows fluid to leak b/w ILM and post vit which will enlarge the spaces
Where does PVD start?
Macula region
What is a partial detachment?
Attachments between retina and vitreous remain intact elsewhere
When is PVD complete?
When its detached from the ONH
What is shown here and how does it occur
A weiss ring- occurs when vit detaches from the ONH
What is an anomalous PVD?
Vit degeneration without detachment
What is residual adherence?
Adherence between vit and retina become under strain due to the ocular mobility
What can anomalous detachment lead to?
Vitreo ret traction which then leads to tears
What are the risk factors to PVD?
- Age (80-90 yrs= 86%
- Myopia- 4-5x earlier
- Gender- Females 2-3x
- Ocular Trauma- Cataract extraction (76%)
How long after would a PVD occur post cataract surgery?
1 week to 1-2 yrs
Mean time- 7 months
What are the sxs of PVD?
- Painless
- Flashes
- Floaters
What are the signs?
- Floaters
- Weiss ring
- Crumpled vit (partial- crumpled milky white, comlete- empty space
Where are the flashes more commonly perceived by the patient?
Temporal VF
Aside from eye movements, what else cause traction as part of anomalous PVD?
Vit haemmorage
What are the signs of vit haemm?
- Fresh well defined edges
2. Obscured blood vessels
What are the sxs of vit haemmorage?
- Sudden
- Small dark floaters
- Red floaters/mist
- Blurred vision/ cloudy vision
- Reduced VA
What other vit haemm causes are there?
Proliferative DM retinopathy
Ocualr trauma
What is the incidence of tears and retinal detachment in non diabetic pxs?
Tears- 70%
Retinal detachment- 40%
When is PVD managed by optoms without a need for referral?
Benign- no complications meaning no tx required
When is an emergency referral required for PVD?
- If increase or change in sxs alone
2. PVD Complicated by vit haemm
If the optom is unable to see the px, what is done in these cases?
Px goes to A+E
Following a PVD what most commonly develops and and long after?
Retinal breaks/tears- develops within 6 weeks
What sxs are suggestive of a retinal break/tear?
- Increase in numeber of floater size
2. ‘Curtain/shadow/cobweb’ develops on part of the VF
What assessment is needed to rule out any tears breaks or detachment?
Dilated fundus exam
Which is the most common form of retinal detachment out of the 3 major forms?
Rhegmatogenous RD
What is the cause of Rhegmatogenous RD?
Formation of breaks in the retinal tissue. This leads to influx of fluid under the retina
Which layers separate in a Rheg RD?
Neurosensory retina from the Retinal pigment epithelium layer
How does the Rheg RD occur?
Smooth continual retinal tissue must be perforated by break. The tension b/w the detaching post vit and ILM can cause the retina to tear
What is the estimated acute and sxs PVDs that will lead to Rheg RD?
7-13%
What keeps the RPE and NSR together?
Weak mechanical forces- microvilli
Where does the fluid accumulate in Rheg RD?
Subretina
What the risk Factors of Rheg RD?
- Fellow eye
- +ve Fam Hx
- PVD- (Acute, sxs, gradual, increased tension, vit haemm, incomplete PVDs)
- Age
- Myopia
- Ocular trauma
- Ocular surgery (Cat)
Which occupations are more at risks of RRD?
Boxers
How are 60 year old compared to <30 year olds likely o develop RRD?
20x more likely
What is the incidence of RRD?
6.8/100,000 people/ year in 25-44 yrs 69.5/100,00 people/ year in 75-84 yrs
How likely are myopes to develop RRD?
Low myopia= 3x
High myopia= 10x
Increase of Axial length by 1mm= risk increases by factor of 1.3x
What is likely risk of RRD post cat surgery?
0.68-0.9%…. usually develop within 1st 12/12
What are the sxs of RRD?
- Flashes and Floaters
2. Acute onset
What are the signs of RRD?
- VA- Unaffected if macula on
- Pupils -ve RAPD usually (extensive= +ve RAPD)
- IOP- compare with effected eye
- VF- Peripheral VF defects
- Tobacco and shafers sign (Ant vit)
- Retinal breaks and tears
What VF assessment would be suitable for a peripheral defects?
Confrontation method
If a positive shafers sign is present, what are the chances of a retinal detachment?
95%
What comprises of the neuro sensory layer?
ILM including the PRL. Tears are only through the neurosensory layer only
What is being shown here?
Shafers/Tobacco dust- small dark brown RPE cells
Where are breaks are commonly found?
Superior temporal 60%
What is a common type of tear?
A horse shoe or u shape. (The black arrow
How would you manage a px with tobacco dust?
TB dust but no tear- an emergency opinion
What signs require emergency referral to ophthalmologist?
- Vitreous haemm
- +ve shafers sign/tobacco dust
- Retinal break, tear or hole
- Retinal detachment
What is the gold standard to check for detachment in the most periphery?
Goldmann 3- mirror lens
(A sclera indentation may be required with this)
What are the different types peripheral Ret degeneration?
- Lattice
- Snail track
- White c pressure
- Other peripheral ret deg
a. Paving stone
b. Microcystoid
c. Honeycomb
Which is the most common and important peripheral degeneration?
Lattice deg
Where is lattice more commonly found?
Myopes
pxs with RRD
Areas with thin/Absent ILM
Why are breaks typical found in the superior temporal periphery?
Vitreous and retina are particularly strong over lattice areas. This increases tension which increases risk of retinal break
What is the distinguished feature of lattice deg?
Sclerosed blood vessels- hardened vessels that appear white. Cause is uncertain
Also feature hyperpigmentation
What to do if patient shows ASYMPTOMATIC lattice degeneration?
No referral needed. Give information about RD sxs and advise emergency eye exam if sxs present.
What are the college of optometrists guidelines for pxs with lattice deg?
Refer as emergency- lattice deg and sxs of PVD/RD even if signs are normal
What is the 2nd most important peripheral degeneration?
Snail track
Where is a snail track located?
Around the equator and young myopes
What are the signs of snail track?
Band of white frost like dots
What is being shown here?
White s pressure- areas are usually demarced
What is being shown here?
Paving stone deg
Which other retinal degeneration have no increased risk of RD?
Paving stone
Microcystoid
Honeycomb
Which degeneration allows you to see choroid blood vessels?
Paving stone
What is the typical location of paving stone degeneration
Inferior retina
What vitreous degeneration are there?
- Asterois hyalosis
2. Retinoschisis
What are the signs of asteroid hyalosis?
Pale yellow white lesions (calcium lipid deposits)
Unilateral ~75%
Move/float c eyemovements- can cause visual sxs
‘Snow globe’
Elderly ~3%
What are the signs of retinoschisis?
Smooth dome shaped elevation Hypermetropes Bilateral Asymptomatic F+F absent No tension NSL elevated Common in inferior retina May have small white dots
What causes retinoschisis?
Aggregation of microcyst in layers causing a split in OPL. This serveres connection between PRL and RGC
What is the prevelamce of retinochisis?
5-7% adults
What is the 2nd most common RD?
Tractional
What is tractional RD associated with?
- Proliferative diabetic retinopathy
- Retinal venous obstruction
- Prematurity retinopathy
- Sickle cell retinopathy
( ALL link to retinal ischaemia which contributes to vitreoretinal membranes)
What is not associated with tractional RD?
- Tears
2. Tabbaco sign
How is Exudative RD formed?
Fluid accumulation b/w BM and RPE also known as PED
What causes exudative RD?
Breakdown of the outer BRB which regulates flow of blood constituents b/w choroid and outer retinal layers
How is the outer BRB broken down and what conditions are responsible?
Inflammatory or retinovascular conditions:
a. Post uveitis
b. Post scleritis
c. Intra ocular or retro Bulbar tumours
d. Infections I.e. tuberculosis and syphilis
What is the ophthalmological management for retinal detachments?
REFER! Same day phone call
When calling the hospital, what information should we give to HES staff?
Case history info-
Is vision effected
When change in vision was noticed
Time scale between loss and F+F
What are the aim for surgical treatment?
Reattach NSR to RPE by - sealing breach, draining subret fluid and providing force c NSR and RPE
How long would a macula ‘ON’ px would be seen for a surgery?
24-48 hours
What surgical interventions are there?
Scleral Buckle
Pars Plana Virectomy
In scleral buckle how are breaks sealed?
Laser and cryotherapy
