Lab 3 - Peripheral Retina Flashcards
What is the difference between retinoschisis and retinal detachment?
Retinoschisis is usually bilateral whilst retinal detachment is generally unilateral.
Retinoschisis is immobile whilst retinal detachment may be mobile.
Retinoschisis results in an absolute visual field defect whereas retinal detachment results in a relative visual field defect
Retinoschisis tends to affect hyperopes whereas retinal detachment tends to affect myopes
Retinoschisis results in outer-inner retinal breaks whereas retinal detachment is a full thickness retinal break.
Describe what you would see upon fundoscopy of a patient with posterior vitreous detachment
Diffuse blurriness of image
Weiss ring - if detached from ONH
Shafer’s sign - brown pigment in vitreous that suggests a retinal tear has occured
Vitreous haemorrhage
What are the two kinds of retinal breaks?
Tear - horse-shoe shaped
Hole - atrophic / operculated
List the 3 kinds of retinal detachments, how they occur and what you would find upon fundoscopy
Rhegmatogenous
- retinal break present
- shafer’s sign may be present
Serous/Exudative
- no retinal break
- fluid accumulation below superficial retina
- dome shaped retina - looks as if a section of retina blurred or dark
Tractional
- secondary to previous haemorrhage, surgery, trauma, infarct, inflammation etc
- fibrotic/fibrovascular membranes = traction on retina
- immobile/does not shift with head movements
What is the difference between lattice and pavingstone degeneration?
Lattice
- linear trail of fibrosed vessels within atrophied retina in a lattice pattern
- atrophic holes often present
predispose to RRD
Pavingstone
- degeneration of choriocapillaris = reduced RPE
- areas of yellow thinned retina with increased visibility of choroidal vasculature with hyperpigmented margins
- does NOT predispose to retinal detachment
Describe what you would see upon fundoscopy of a patient with retinoschisis
Balooning retinal elevation with clearly demarcated borders
Holes may develop in inner/outer layers
Similar to RRD but immobile, asymptomatic and causes an absolute scotoma.
Describe what you would see upon fundoscopy of a patient with WWOP
grey/white, somewhat translucent retina
- looks like a foggy/desaturated retina with a clearly demarcated area
What is the pathophysiology of PVD
Aging results in a reduction of hyaluronic acid, resulting in a loss of support to collagen.
Fine collagen fibrils congregate, forming small floating opacities.
The vitreous moves more readily with eye movement and trauma, tugging the hyaloid membrane away from the inner limiting membrane.
The vitreous may collapse, with detachment of posterior hyaloid face from the ONH
What is the pathophysiology of lattice degeneration?
Dropout of peripheral retinal capillaries results in ischaemia, leading to thinning of all retinal layers. This causes:
Disturbance of the overlying vitreous which casues pockets of liquefaction overlying lattice lesions
Strong vitreoretinal adhesion along edges of lattice lesion
Disturbs RPE = RPE hyperplasia and pigmented appearance
Sclerosis of larger vessels gives lattice its characteristic fibrotic appearance
Retinal thinning can become so profound that a full thickness hole atrophies through retina at lattice lesion, leading to RRD
What is the pathophysiology of pavingstone degeneration?
Degeneration of choriocapillaris leads to subsequent loss of RPE
- allows direct contact between remaining thinned neural retina and choroidal connective tissue
What is the pathophysiology of retinoschisis
Splitting within retina at outer plexiform layer.
Degenerative form, due to coalescence of cysts from microcystoid degeneration. Retina splits into inner and outer cavity if enough cystic spaces coalesce
Inner/outer/both layers may develop holes, leading to RRD (if in outer layer)
