retinal vascular diseases

• diabetes

  type 1 - insulin deficiency, pancreas cant produce enough insulin; hyperglycemia

  type 2 - insulin resistance, body does produce insulin but it isnt effective

  gestational -cant make enough insulin during pregnancy

  specific types - monogenic diabetes syndrome - presentation of non insulin dependent diabetes occuring in young people with strong autosomal dominance
• complications of diabetes

  • diabetic retinopathy - high blood surgar damages retina affecting blood vessels and causing vision loss
  • diabetic maculopathy - blood vessles in macula become leaky and blocked
  • refractive error
  • iridopathy - change of iris colour
  • senile cataracts - high blood sugar can cause stuctural changes in the lens and accelerate cataract development
  • styes, bleph, xanthelasmata (plaques on lids)
  • subconj haem
  • ocular motor palsies - reduced eyeball movement
  • corneal ulcers and sesntivity
  • rubeosis iridis - new vessels grow in iris and can cover trabecular meshwork - leads to secondary glaucoma (neovascular)
• risk factors for retinopathy

  • duration - most important, 90% have diabetic retinopathy 30 years after diagnosis but onlt 5% show with it on initial presentation
  • increased chance of retinopathy while having type 2
  • poor control - good control reduces incidence and progression of DR especially in type 1
  • pregnancy - increases risk of DR progression
  • hypertension - good control reduces risk in type 2
  • nephropathy - severe disease impacts DR
  • obesity - linked to increase in DR risk
  • consider smoking, aenemia, hyperlipidemia (serum lipids)
• what does raised glucose result in

  • increased blood viscosity
  • basement membrane thickening and damage
  • pericyte degeneration
  • endothelial cell proliferation and degeneration
  • retinal capillary closure in both superficial and deep beds
• damage to microvasculature

  • affects organs
  • chronic leakage from vasculature results in oedema and exudates
  • bulges in side of walls breaching integrity
  • hard exudates will persist once oedema disappears
  • retinal ischaemia - loss of oxyfen stimulates productions of growth factors such as VEGF, IGF-1 leading to neovascularisation (new vessels are weak and leak so fluid leak of oedema and prone to haemorrhage)
  • AV shunts make up loss of vessles - role of capillaries

  
• Background diabetic retinopathy - earliest stage

  • microanyeurisms bulged on individual capillaries
  • dot and blot haemorrhages with leakage in outer nuclear and inner plexiform layers
  • flame haemorhages where vessels branch hearer to the retinal surface and hard exudates occur around area of oedema

  
• pre proliferative diabetic retinopathy

  • cotton wool spots - localised ischemia of nerve fibre layer causes swelling
  • intra retinal microvascular abnormality - capillary bed starts to break down, venous beading and looping due to damage, signs of ischemia in retina ie lack of oxygen
  • can get neovascularisation - new vessel growth which is leaky and prone to haemorrhage, obstructs vision and takes long time to clear, leads to fibrosis which contracts and leads to tractional retinal detachment

  
• proliferative diabetic retinopathy

  • neovasc at the disc (NVD) = leaky, fan like protrusions of vessels on disc
  • protrusions of vessels elsewhere = NVE
  • pre retinal and vitreous haemorrhages - flat top surface due to gravity in image 3
  • tractional retinal detachment

  
• diabetic maculopathies

  • diabetic changong occuring in the macula
  • exudative, focal, diffuse, cystoid/diffuse oedema
  • ischaemia - loss of capillaries means loss of oxygem but macula appears to look normal with poor VA

  
• clinically significant macular oedema

  • retinal oedema within 500um of centre of fovea
  • hard exudates within 500um of centre of fovea, if associated with retinal thickening can be outside this area
  • retinal oedema 1 disc area or larger, any part of which is within 1DD of the central fovea
  • exudates associated with oedema

  
• overview of diabtic retinopathy

  • see table

  
• crystaline lens and diabetes

  • diabetes and hyperglycemia can cause reversible snowflake and irreversible patterns
  • early onset of age related cataract - reversible or irreversible
  • nuclear catarct more common in diabetes with fast progression
  • classically myopic shifts because taking up sorbitol in lens changes refractive index
  • transient hyperopia after strict metabolic control
  • lens increases by0.3mm in diameter but refractive index reduces from 1.42 to 1.4 so about 3D
  • mean shift around 3 diopters

  
• iris complications with diabetes

  • iris transillumination in type 2 diabetes
  • rubeosis iris - new vessels growing on iris
  • pupil size - small and irregular, sympathetic denervation
  • increased IOP due to leakage of cells from new blood vessels due to build up of cells in trabecular meshwork
• extraocular muscle palsies and diabetes

  • px with 3rd nerve palsy affecting levator palpebrae superioris if raised lid then eye positions down and out
  • ischemic third nerve palsy can spread to pupil
  • ischemic microvascular damage - extra ocular muscle palsy
  • can affect 3,4,6 cranial nerves 6 most common in diabetic px - abducens
  • high HbA1c (poor control) associated with increased risk of developing a nerve palsy

  
• lids and lashes in diabetes

  • can get bleph, styes and infections
  • xanthelasma - associated with hyperlipidaemia; yellow tinge to lids

  
• corneal complications associated with diabetes

  • recurrent epithelial erosions
  • transient punctate keratitis
  • stromal oedema
  • reduced corneal sensitivity
  • reduced healing rate
  • increased fertility
  • reduced resistance to infection
  • increased association with arcus senilis - lipid deposits appear as ring around cornea
• hypertension

  • primary hypertension - 90% cases
  • secondary hypertensiuon - 10% cases from renal disease, endocrine disease or rarely congenital disease
  • resistant hypertension - BP cant be reduced by treatment
  • above 140/90 either systolic or diastolic
  • accelerated hypertension - BP 190/120 with signs of reitnal haemorrhage or papilloedema with optic nerve swelling - also known as malignant hypertension - med emergency
• hypertension and the eye

  • ocular signs are hypertensive retinopathy - high BP damages the retina
  • choroidopathy - affects blood vessel layer which supports the retina
  • disc oedema

  associated ocular complications

  • anterior ischemic optic neuropathy - optoc nerve cant recieve blood flow so vision loss, non arteritic so reduced VA and swollen disc
  • retinal arteriole and vein occlusions
  • retinal macro aneurysms - bulge in small retinal artery leading to vision loss and retinal emboli/ opacities in arterioles
  • ocular motor nerve palsy
  • glaucomatous optic neuropathy - disease damaging the optic nerve causing vision loss and blindness
• hypertensive retinopathy

  • vasoconstrictive phase - autoregulation mechanism results in vascularisation visible as generalised arteriole narrowing which affects BP
  • sclerotic phase - persistent high BP leads to hyalinised walls and loss of muscle cells around muscle walls associated with changes in arterial light reflex and A/V crossing seen in opthalmoscopy ; microanyeurisms, CRA and CRV occlusion, epiretinal membrane,
  • exudative phase - blood retinal barrier disrupted due to loss of smooth muscle and endothelial cells - haemorrhages, oedema, cotton wool spots, localised ischemia, disc swelling = malignant hypertension and high BP
• what is an epiretinal membrane

  • forms during complications in sclerotic phase of hypertensive retinopathy
  • thin layer of scar tissue forming on surface of retina which occurs when vitreous gel inside eye changes causing cells to multiply on the retina and form a sheet
• major signs of hypertensive retinopathy

  • retinal oedema
  • hard exudates - lipid deposits
  • cotton wool spots
  • retinal haemorrhages
  • FIPTS - focal intraretinal periarteriolar transudates = severe increase in blood pressure which damages blood retinal barrier, allows macromolecules to accumulate in retina, build up of plasma in retina and along deep retinal arterioles, white oval lesions 1/4 of DD size
  • IRMA - intraretinal microvascular abnormality due to capillary occlusion
• retinal grading

  2 grading systems

  • keith wagener barker classification
  • scheie classification system
  • nipping - arteries cross veins
  • arteriosclerosis - hardening of vessels and arteries
  • silver wiring or copper wiring - walls of arterioles become thickened and sclerosed so reflect more light on examination

  
• hypertensive retinopathy image and notation

  • silver wiring/ copper wiring = walls become thickened and sclerosed so reflect more light on examination
  • nipping - arterioles cause compression of veins due to hardening and sclerosis
  • cotton wool spots - ischaemia and infarction of retina causing damage to nerve fibres
  • hard exudates - caused by damaged vessels leaking lipids
  • retinal haemorrhages - vessels rupturing, dot and blot = deeper in inner nuclear layer or outer plexiform layer, flame haemorrhages in nerve fibre layer
  • papilloedema - ischaemia to optic nerve = swelling

  
• kieth - Wagener classification

  • mild narrowing of arteries
  • focal constriction of blood vessels and nipping
  • cotton wool spots, exudates and haemorrhages
  • papilloedema

  
• vessel changes

  Gunns sign - concealment of vein as artery overlaps it

  Salus sign - deviation of vein out of its path, deflection in vessel due to hardening of artery

  bonnet sign - elevation of vein over artert or compression of vein at crossinf causing stenosis of distil vein (narrowing on either side of artery)

  
• Gunns sign vs Bonnets sign in the eye

  • see images
  • copper wiring - reflex on top of vessel which is chronic once happens

  
• acute hypertensive signs

  • flame haemorrhages and cotton wool spots
  • exudates - can form macular star
  • blood retina barrier becomes compromised

  
• aneurysms in hypertensive retinopathy

  • bulge in vessel caused by weak spot in blood vessel

  
• disc oedema and malignant hypertension

  • caused by raised IOP or disc ischaemia so low blood flow
  • rule out AION as more likely

  
• hypertensive choroidopathy

  • severe hypertension - in young people
  • associated with renal disease, toxemia of pregnancy (disease caused by bacteria in blood stream) or collagen vascular disease
  • clinical signs are RPE lesions - Elshnigs spots, siegrists streaks
  • can develop serous detachments of neurosensory retina

  
• hypertensive retinopathy signs and stroke risks

  • cotton wool spots sign of ischemia
  • if present high risk of strokes
  • top 3 on graph are current symptoms whereas rest are chronic symptoms

  
• overview of hypertensive retinopathy

  • see table

  
• prevalence of hypertension in retinovascular disease

  • see graph
  • BRAO - branch retinal artery occlusion
  • CRAO - central retinal artery occlusion
  • BRVO - branched retinal vein occlusion
  • CRVO- central retinal vein occlusion
  • NAION- non arteritic anterior ischemic optic neuropathy
• causes of retinal vein and artery occlusions

  • caused by compression of vein wall
  • prevents normal blood flow
  • artherosclerotic changes in vessel walls
  • high intra arterial pressure which leads to narrowing of vessel and thrombus development which blocks flow of vein - occur in lamina cribrosa leading to central retinal vein occlusion
  • can be caused by increased blood viscosity, diabetes, vasculitis from inflammation or swelling of vessels, prothrombophillic disorders ie blood clots
• comparing occlusions

  CRVO - due to thrombosis of central retinal vein at the lamina crribrosa or retro laminar

  BRVO - occlusion at an AV crossing, 7x more common than CRVO and 2 thirds occur in the superotemporal quadrant

  Hemi retinal vein occlusion (HRVO) - occlusion at the optic disc, only affecting one of the 2 retinal branches
• central retinal vein occlusion

  • haemorrhages
  • dilated and tortuous veins
  • optic disc oedema
  • cotton wool spots - ischaemia
  • all 4 quadrants involved
  • no flow through veins causing haemorrhage and oedema

  
• branch retinal vein occlusion

  • disc swelling uncommon
  • may also have cotton wool spots and localised oedema
  • haemorrhages alongside one arcade only - normal vasculature not affected

  
• hemi retinal vein occlusion

  • one side of retina only
  • ischemia = less than normal blood flow to the body
  • haemorrhage only on one side of fundus

  
• ischaemic vs non ischemic occlusion

  • cant tell by looking
  • now thought to be a spectrum with all venous occlusions having an element of ischaemia
  • can lead to neovascularisation of the iris

  in ischaemic occlusions

  • VA less than 6/60 so more severe
  • RAPD present - pupils respond to light differently due to asymmetrical disease of retina or optic nerve
  • severe disc and macula oedema
  • neovascular changes = disc NVD, retina NVE or NVI iris

  differential diagnosis

  • ocular ischaemic syndrome
  • asymmetrical diabetic retinopathy - one eye rather than both
  • hypertensive retinopathy
  • macro aneurysm
  • peripheral choroidal neovascularisation
• optometric investigations

  • VA
  • colour fundus photography
  • gonioscopy - especially if ischaemic CRVO suspected, measure angle between cornea and iris to check for glaucoma - help to look for neovasc at the iris - fine and red
  • OCT - oedema picked uo
  • IOP check - understand retinal artery supply, recognise signs and symptoms of retinal artery occlusion, risk factors for occlusion and management/prognosis of artery occlusion