retinal arterial obstructions

Retinal Arterial ObstructionsRetinal Arterial Obstructions

DR.SHAH-NOOR HASSAN FCPS,FRCS Assistant Professor Vitreo-Retina Unit Dept. of Ophthalmology BSMMU

Introduction Introduction Retinal arterial obstructive diseases can

manifest in different clinical forms.Classification:

1. Central retinal artery obstruction (57%)2. Branch retinal artery obstruction (38%)3. Ciioretinal artery obstriction (5%)4. Combined CRAO and CRVO5. Cotton-wool spots

HistoryHistory

Von Graefe 1859: Embolic CRAO in patients with endocarditis

Sweiger 1864: Histopathological description

Mauthner 1868: Spasmodic contractions could lead to retinal arterial obstruction

Loring 1874: Focal obstructive disease within retinal vessels as the cause

AetiologyAetiology

Intramural◦ Emboli◦ Thrombus

Mural◦ Luminal narrowing

Extra-mural◦ External compression

Intra-mural- EmboliIntra-mural- EmboliMost common cause of retinal arterial

occlusionsVisible in 20-40% of arterial occlusionsSystemic implications◦ 9 year mortality-56% with emboli

27% without emboliTypes:◦ EXOGENOUS◦ ENDOGENOUS

Endogenous emboliEndogenous emboliCholesterol emboli◦ Glistening yellow◦ Small peripheral asymptomatic block

Fibrin-platelet emboli◦ Dull, grey, elonagetd, multiple◦ Fills the entire lumen

Calcific emboli◦ Larger, more severe obstruction◦ Single, white, near the disc

Endogenous emboliEndogenous emboli

Fat emboli Long bones

Amniotic fluid emboli Complications of pregnancy

Tumor emboli Atrial myxoma

Erythrocyte aggregation Sickle cell disease

Leuko-emboli

Exogenous EmboliExogenous EmboliAir emboli◦ Trauma or surgery

Talc◦ IV drug abuse impurities

Corticosteroid◦ Intralesional Rx

Synthetic material◦ Valves, catheters, prosthesis

Luminal narrowingLuminal narrowingAtherosclerosis with thrombosis◦ Commonly seen with CRAO

Haemorrhage into the atheromatous plaque

VasospasmVasculitis

Atherosclerosis-related thrombosis at the level of the lamina cribrosa is by far the most common underlying cause of central retinal artery occlusion (CRAO), accounting for about 80% of cases. Atherosclerosis is characterized by focal intimal thickening comprising cells of smooth muscle origin, connective tissue and lipid-containing foam cells .

Blood VesselBlood Vessel

External compressionExternal compressionDisc oedema◦ Papillitis◦ Papilledema◦ AION◦ CRVO

RB injectionOcular Compression◦ During surgery

Retinal HypoperfusionRetinal HypoperfusionSystemic hypotensionOcular hypertensionBlood dyscrasias

Central retinal artery occlusionCentral retinal artery occlusion

Introduction Introduction Blockage within the optic nerve

substance-CRAOBlockage distal to lamina-BRAO

Incidence and DemographyIncidence and Demography1:10,000 of outpatient visits57% of the arterial occlusionsOlder adultsEarly sixtiesM>F1%-2% bilateral: consider cardiac valvular

disease, giant cell arteritis and other vascular inflammations

Clinical featuresClinical features

Sudden onset painless visual loss occurring over several seconds

Preceding history of amaurosis fugaxAfferent pupillary defect develops

secondsAnterior segment:◦ Initially normal

Cont… Cont… Vision◦ 90% cases: CF to PL◦ No PL: choroidal or optic nerve damage◦ 10% cilioretinal artery spares foveola

VA>20/40 in 80% over 2 weeks Small island of central vision

Clinical features: posterior segmentClinical features: posterior segment

Yellow-white opacified retina :◦ Ischaemic necrosis affecting the inner half

of the retina◦ Less in areas outside the macular area

Cloudy swellingCherry red spot at the foveola:◦ Extremely thin foveal retina◦ View of underlying RPE and choroid◦ Nourished underlying choroid

Clinical featuresClinical featuresAttenuated retinal arteriesRetinal veins: can be thin, dilated or even

normal in appearanceSegmentation or “boxcarring” of the

blood column: in severe obstruction

Later stagesLater stagesOpacification vanishes in 4-6 weeksPale disc Narrowed retinal vesselsVisible absence of nerve fiber layer in the

region of optic discPigmentary changes: choroidal circulation

is involved

Clinical featuresClinical featuresPresence of emboli: poor prognosis

Emboli seen in 20%-40% of CRAO◦ Hollenhorst plaque (Cholesterol emboli)◦ Calcific emboli

Cholesterol emboliCholesterol emboli Hollenhorst plaque Most common variant Glistening, yellow coloured Small Usually do not obstruct the complete lumen Origin

atherosclerotic deposits in the carotid arteries Aortic arch Ophthalmic artery Proximal central retinal artery

Calcific emboliCalcific emboliLess commonLarger and cause more severe

obstructionOriginate from cardiac valves

Neovascularization Neovascularization 20 % acute central retinal artery

obstructionMean time of 4-5 weeks (range 1 to 15

weeks)NVD 2%-3%If NVI and NVD already present at the

time of acute CRAO- suspect underlying carotid artery obstruction

InvestigationsInvestigations

Fluorescein AngiographyFluorescein Angiography

Delay in the retinal arterial filling (most specific)

Delay in the arterio-venous transit time(most sensitive)

Late staining of the optic disc

Complete lack of filling of retinal arteries-2% cases

FAFA

FAFAChoroidal filling is usually normal◦ Prolongation of choroidal filling in presence of

cherry-red spot s/o ophthalmic or carotid artery obstruction

FA reverts back to normal at later stages as the circulation re-establishes

ERGERG Decrease in the amplitude of

b-wave a-wave is unaffected May be normal in some eyes

in spite of less vision because of re-establishment of retinal blood flow

Visual fieldsVisual fieldsRemaining temporal island-choroid

nourishing corresponding temporal retinaSmall island of central vision-patent cilio-

retinal artery

OCTOCT

Diffuse thickening of the neurosensory retina. Increased reflectivity was noted from the inner retinal layers corresponding to retinal ischemia and decreased backscattering was observed from the retinal photoreceptors.

OCT SpectralisOCT Spectralis

PathologyPathology Site: Lamina cribrosa or its posterior aspect First week:

Inner layer intracellular oedema

Pyknosis of the ganglion cell nuclei

Ischaemic necrosis Posterior pole:thick NFL and ganglion cells

Chronic: Diffuse inner retinal atrophy Homogenous scar formation

Pathology Cont..Pathology Cont..

Systemic associationsSystemic associations90% have systemic disease2/3rd of patients have HTN1/4th have DM45% show Carotid atherosclerosisIncreased thrombogenecityCardiac valvular disease

List of systemic causes…..List of systemic causes….. Arterial hypertension Carotid atherosclerosis Cardiac valvular disease Rheumatic mitral valve prolapse Mural thrombus after MI Cardiac myxoma Tumours IV drug abuse Lipid emboli Pancreatitis Purscher’s retinopathy

Loiasis Radiologic studies Carotid angiography Lymphangiography Hysterosalpingography Head & neck corticosteroid

inj Retrobulbar injections Trauma Orbital # repair Anaesthesia Drug or alcohol induced

stupor Coagulopathies Sickle cell disease

List continues…List continues… Homocystinuria Oral contraceptives Platelet and factor

abnormalities Pregnancy Prepapillary arterial

loops Optic disc drusen Increased IOP Collagen-vascular

diseases SLE PAN

GCA Ventriculography Fabry’s disease Sydenham’s chorea Migraine Hypotension Fibromuscular

hyperplasia Optic neuritis Orbital mucormycosis

Differential diagnosisDifferential diagnosisBilateral◦ Cardiac valvular disease◦ Giant cell arteritis◦ Vascular inflammations

Aminoglycoside toxicityPurtscher’s retinopathy

Management Management Ocular emergency Irreversible damage – 90 to 100 mins Aim: is to restore the circulation Recovery noted to occur till 3 days after the event Give ocular treatment if patient is seen within 24

hours

Modalities: Ocular massage Carbogen Anterior chamber paracentesis Fibirinolytic agents Other modalities

Transluminal Nd:YAG laser embolysis has been advocated for BRAO or CRAO in which an occluding embolus is visible; shots of 0.5–1.0 mJ or higher are applied directly to the embolus using a fundus contact lens. Embolectomy has been said to occur if the embolus is ejected into the vitreous via a hole in the arteriole. The main complication is vitreous haemorrhage

Ocular massageOcular massageIn and out movement with three-mirror

(Goldmann)contact lens or digital massage

Can dislodge an obstructing embolus-rare

Increase pressure for 10-15 secs followed by sudden release

Produces arterial dilatation improving retinal perfusion

86% increase in volume of flow

Oxygen and COOxygen and CO2 2 (Carbogen) (Carbogen)

95% O2 and 5 % CO2

CO2:◦ Vasodilator ◦ Increases retinal blood flow

100% O2

◦ Vasoconstriction◦ Normal pO2 through diffusion from choroid

◦ Improves visual function in CRAORebreathing in the paper bag

AC paracentesisAC paracentesisCauses sudden decrease in the IOPPerfusion pressure behind the

obstruction pushes the obstructing embolus

Fibrinolytic agentsFibrinolytic agentsDelivered via injection through

supraorbital arteryReaches CRA in doses 100 times greater

than by systemic administrationVision improvement noted in 50% of the

patients

Other treatment modalitiesOther treatment modalitiesRetrobulbar or systemic vasodilators:

papaverine or tolazolineSublingual nitroglycerineSystemic anticoagulants

Systemic EvaluationSystemic Evaluation

Many patients will have a history of vascular disease.

Enquiry should be made about smoking.       

Symptoms of GCA should be kept in mind in older age group   

  Pulse particularly to detect atrial fibrillation.

Blood pressure

   Carotid examination.       

   ECG to detect arrhythmia and other cardiac disease.

   Erythrocyte sedimentation rate and C-reactive protein to detect the remote possibility of GCA.  

   Other blood tests include FBC, random glucose, lipids, urea and electrolytes.

   Carotid duplex scanning is a non-invasive screening test involving a combination of high-resolution real-time ultrasonography with Doppler flow analysis. If significant stenosis is present, surgical management may be considered.

Special testsSpecial testsEchocardiography Usually performed

if there is a specific indication such as a history of rheumatoid fever, known cardiac valvular disease.

Chest X-ray - Sarcoidosis, tuberculosis, left ventricular hypertrophy in hypertension

Additional blood testAdditional blood test

   Fasting plasma homocysteine level Thrombophilia screen

   Plasma protein electrophoresis

   Autoantibody

   Blood cultures.

BRAOBRAO

PresentationPresentationSeventh decadeSudden, painless loss of visionCorresponding visual field deficitH/O amaurosisH/O transient ischaemic attack or

strokes1/3rd have H/O carotid occlusive disease

or hypertension

Funduscopically Funduscopically Localized region of superficial retinal whiteningProminent at the posterior pole, along

distribution of obstructed vesselIntense whitening at the borders of

ischaemic areas: secondary to blockage of axoplasmic flow

90% involve temporal retinal arteries

Prognosis Prognosis Good if foveola is not surrounded by

retinal whitening80% improve to 20/40 or betterResidual visual field remainsPosterior segment neovascularizationIris neovascularizationArtery-artery collateral vessels –

pathognomic of BRAO

FFAFFADelayed or no filling of occluded branchHypofluorescence◦ Lack of perfusion◦ Blockage by edema

Retrograde filling of distal veinsFlow restored after dissolution of

obstruction

Cilio-retinal artery Cilio-retinal artery obstructionobstruction

Cilio-retinal arteryCilio-retinal arteryClinically 20%; Angiographically 32%Fill concurrently with choroidal

circulation 1-2 secs before retinal circulation

Papillo-macular retinal circulationSupplies foveola in 10% of cases

Presentation Presentation Sudden onset visual lossArea of superficial retinal whitening 3 clinical variants◦ Isolated◦ Associated with CRVO◦ Aoosciated with AION

Isolated cilio-retinal artery obstruction (40%):◦ Good visual prognosis◦ 90 % 20/40 or better◦ Intact superior and inferior NFL bundles

With CRVO (40%)◦ Seen in 5% of CRVO (non-ischaemic)◦ 70% >20/40◦ Low hydrostatic pressure in cilio-retinal

artery as compared to CRA◦ Swelling of the optic disc

Associated with AION (20%): ◦ Poor visual prognosis◦ 20/400 to no PL◦ Optic nerve damage◦ Hyperaemic or pale disc along with retinal

whitening Acute pale swelling s/o GCA

◦ Posterior ciliary insufficiency

Carotid artery Carotid artery obstructionobstruction

Presentation Presentation Visual loss (20/20 to No PL)Severe pain due to ischaemia or NVGDot-blot haemorrhages, narrowed

arteries, dilated veinsFFA:◦ Increase in the A-V transit time (95% cases)◦ Prolonged patchy choroidal filling (60%)

CourseCourseVisual improvement takes several weeks◦ poor visual prognosis

Optic atrophy, arteriolar attenuation, NVE

NVI in 2/3rd cases (NVG in half)

InvestigationsInvestigations Digital ophthalmodynamometry

Decreased ocular perfusion pressure Diminished or absent pulse of ipsilateral

cervical carotid artery Bruit if partial stenosis

Absent if complete stenosis Digital subtraction angiography, MRI,

Intra-arterial angiography

Management Management To prevent permanent vision loss and

strokeScreen for systemic illnessesAntiplatelet therapyAnticoagulantsCarotid end-arterectomy◦ Stenosis greater than 70%

Combined retinal artery Combined retinal artery and vein occlusionand vein occlusion

Presentation Presentation Retrobulbar injections-1/4th of cases Clinical features of CRVO & CRAO Sudden onset of painless loss of vision Fundus:

Superficial retinal opacification Cherry red spot

Dilated and tortuous retinal veins Retinal haemorrhages Swollen optic disc

Central retinal artery obstruction

Central retinal vein occlusion

Fluorescein Angiography◦ Severe retinal capillary non-perfusion◦ Sudden termination of mid-sized retinal vessels◦ Minimal leakage-shutdown of retinal vessels

Visual prognosis◦ Poor ◦ Within HM range◦ 80% develop rubeosis and NVG (6 weeks)◦ Aggressive PRP to prevent rubeosis (may fail)

Cotton-wool spotsCotton-wool spots

Cotton-Wool Spots (soft exudate)Cotton-Wool Spots (soft exudate)Yellow white lesion in superficial retina

with feathery margins

Less than 1/4th DD

Correspond to areas of retinal capillary non-perfusion or bordered by microaneurysmal abnormalities

CWSCWSDevelop secondary to obstruction of a

retinal arteriole and resultant ischaemiaHypoxia ->blockage of axoplasmic

transport within NFL -> deposition of intra-axonal organnels

Largely made of mitochondria and lipidLight microscopy: ◦ Cytoid bodies◦ Cellular appearing bodies with psedonucleus

CWSCWS Spots in the visual field may cause a small

scotoma Most resolve within 5-7 weeks May remain longer in diabetic pts. 95% cases have some systemic disease Even one cotton-wool spot in non-diabetics

warrants evaluation Common causes:

Diabetes Mellitus Systemic Arterial Hypertension

To conclude…..To conclude…..Retinal artery occlusion is an ocular emergency

Immediate intervention improves chances of visual recovery, but even then, prognosis is poor.

Follow up for ocular neovascularization needed

Although restoration of vision is of immediate concern, retinal artery occlusion is a harbinger for other systemic diseases that must be evaluated .

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