Retinal Pathology Flashcards
What is the most common cause of rhegmatogenous RD in childhood
Stickler’s syndrome (inherited)
What is retinoschisis and what can it lead to?
Acid mucopolysaccharide filled cavities split the neurosen- sory retina at the outer plexiform layer (typical retinoschisis) or the nerve fibre layer (reticular retinoschisis)
Can lead to rhegmatogenous retinal detachment
Where do retinoschisis occur?
Inferotemporal retina and bilateral
What is lattice degeneration?
Demarcated, circumferentially orientated areas of retinal thinning
Adjacent to the vertical meridian peripherally.
Atrophic small and round retinal holes can be present.
There is an associated risk of retinal detachment.
What histological abnormalities are seen in diabetic retinopathy?
Pericyte loss
Multilayering of the basement membrane
Degeneration of endothelial cells
Results in capillary non-perfusion and tissue ischaemia
What are signs of diabetic retinoapthy?
Micro-infarction (cotton wool spots)
Hard exudates
Microaneurysms
Haemorrhage
Neovascularisation
What are cotton wool spots? What layer of the retina?
Swollen ends of interrupted axons
NFL
What are hard exudates? What layer?
Reduced perfusion of the vascular bed and damage to the endothelium of the deep capillaries causing plasma leakage into the outer plexiform layer
Yellow well circumscribed area
What are hard exudates seen as histologically?
Foamy macrophaes with lipidW
hat are microaneurysms?
Ischaemia of the capillary bed - weakening of the wall by necrosis of the pericyte
- bulging of vessel wall
What are flame haemorrhages layer?
Rupture of small arteriole leading to leak in the NFL (superficial)
What are dot haemorrhages? Layer?
Rupture of capillaries in the outer plexiform layer
What are blot haemorrhages
Larger than dot haemorrhages
Bleeding from capillaries with tracking between photorecptors and RPE
What is the order of haemorrhages in terms of layers?
Superficial - NFL - flame
Between photoreceptors and RPE - blot
Outer plexiform - deep - dot
What are intraretinal microvascular abnormalities
New vessel growing from venous side of capillary bed within an area of arteriolar non-perfusion.
Can leak on FFA and progress to vasoproliferative retinopathy
Which side of the capillary bed do new vessels grow?
Venous side
What is vasoproliferative retinopathy?
Ischaemic areas of retina release VEGF
Diffuse into retina and vitreous
Stimualte endothelial cell proliferation at the edge of the ischaemic area
New vessels form in prevenular capillaries and venules and proliferate whtin and on surface of retina
Diffusion of vasoformative factors to the iris surface and trabecular meshwork can lead to ruebosis iridis
What happens in retinoapthy of prematuriy?
Blood vessels grow from disc towards periphery in utero driven by relative hypoxia
Prem infant on supplemental O2 - reduced hypoxic drive - extension of vascular bed inhibited
Infant returns to normal oxygen levels - excessive proliferation
Ischaemic peripheral non-vascularised retina
- further driving neovascularisation from peripheral vessels - grow rapidly and disorganised
Can lead to bilateral RD
What occurs in hypertensive retinopathy
Hylinization of blood vessels leads to the appearance of copper or silver wiring
Narrowing of the vessels with spasm produces ischaemic effect on endothelial cells
Endothelium swells and degenerates
Leakage of fibrin into the vessel wall occurs
Further narrowing of lumen
Fibrinoid necrosis of choroidal and retinal vessels
What is Eschnig’s spots
In hypertensive retinoapthy if the choriocapillaris is involved, lobular infarcts form Eschnig’s spots
What causes CRAO
USually embolus from atheromatous plaque of carotid artery
Why is the macula spared in retinal pallor?
Thinness of fovea and lack of neuronal tissue allowing a view of the choriocapillairs creating cherry red spot
Where is the central retinal vein narrowed/
In the lamina cribrosa fo the optic disc
- increased resistance provided by venous narrowing increases flow leading to turbulence and increased risk of thormbosis
When are patients more likley to develop neovascularisation and rubeotic glaucoma
CRVO
Unlikely in CRAO
