RETINAL VEIN OCCLUSION

Dr KN POORNESH

WGH

03.11.2004

CLASSIFICATION

BRVO CRVO Major BRVO Non-ischemic

Minor Macular BRVO Ischemic

Peripheral BRVO Papillophlebitis

Hemiretinal Vein occlusion

PATHOGENESIS

Arteriosclerosis

Compression of the vein

Venous endothelial cell loss

Thrombus formation

Venous Occlusion

PATHOGENESIS

Venous occlusion elevation of venous

& capillary pressure

Stagnation of blood flow

Increased tissue pressure Hypoxia of the retina

Damage to capillary endothelial cells &

extravasation of blood constituents

RISK FACTORS(in order of importance)

1. Advancing age: 50% cases over 65 yrs.2. Systemic: HT, Hyperlipidemia, Diabetes,

Smoking, Obesity.3. Raised IOP: risk of CRVO4. Inflammatory: Behcet’s, Sarcoid,AIDS,

SLE, Toxoplasma.5. Hyperviscosity: Polycythemia, MM,

Waldenstrom macroglobulinemia.

RISK FACTORS6. Acquired thrombophilic: Hyperhomocystinemia,

Antiphospholipid antibody syndrome.7. Inherited thrombophilic: increased levels of

clotting factors 7 & 11, deficiency of antithrombin 3, protein C &S, resistance to activated protein C.

Other Risk factors: • Hypermetropia (BRVO), Congenital anomaly of

Central retinal vein (CRVO), Optic disc drusen, • Drugs (OC, Diuretics), Migraine (rare). • Retrobulbar external compression: Dysthyroid eye

disease, Orbital tumor

Major BRVO

COURSE of BRVO

6 to 12 months to resolve • Venous sheathing • Collateral venous channels • Microaneurysms, Hard exudates,

Cholesterol crystal deposition. • Macula: RPE changes or ER gliosis, chronic CME.

Prognosis and Complications of BRVO

Depends on • Site & Size of occluded vein • Integrity of perifoveal capillary network

50% : Recover VA of 6/12 or better.

Complications: 1. Chronic macular edema 2. Macular ischemia 3. Neovascularisation, NV (within 3 yrs) 10%- NVD, 20-30%- NVE 4. Recurrent VH, TRD.

Management of BRVO(BVOS)

Wait for haemorrhage to clear (3 months).FFA : Macular edema and VA 6/12 or worse after 3

months –grid laser & follow-up after 2-3 months.

Macular ischemia—no treatment. 5 DD or > area of CNP– 4 monthly follow- up

for 12-24 months. Neovascularisation– scatter laser

CRVO Ischemic Non-ischemic

Frequency 25% 75%VA 20/400 or < (90%) > than 20/400 (90%)

Site at lamina cribrosa Far behind lam crib

RAPD marked slight

VF defect common rare

Fundus Ext hgs & cotton wool spots, severe disc edema, marked tortuosity of vessels

Less exten hgs, few cotton wool spots, mild disc edema, variable tortuosity of vessels

CRVO Ischemic Non-ischemic

FFA Wide spread capillary non- perfusion

Delayed venous return, late leakage, good perfusion.

ERG Reduced “b” wave amplitude, reduced “b/a” ratio

normal

Prognosis 50% develop rubeosis & NVG in 2-4 months

3% develop rubeosis and NVG.

50% return to VA 6/12 or better.

Non-ischemic CRVO(Course and Follow-up)

Residual signs: Disc collaterals, epiretinal gliosis, pigmentary changes at macula.

Conversion to ischemic CRVO occurs in 15% of cases within 4 months and 34% within 3 years.

Follow-up: should be for 3 years.Prognosis: depends on initial VA, near normal

VA in 50%, Chronic CMO- unresponsive to laser (CVOS).

8-10% risk of BRVO or CRVO in the fellow eye.

Ischemic CRVO:Management (CVOS)

Follow-up: monthly for 6 months IOP, undilated gonioscopy & SLEAngle NV is the best clinical predictor

of NVG.Treatment: PRP in eyes with angle

or iris NV. Monthly follow-up until stabilisation or regression.

Hemiretinal vein occlusion

Less common than BRVO and CRVO

Occlusion of superior or inferior branch of the CRV.

Features of BRVO, involving the superior or inferior hemisphere

Prognosis depends on severity of macular edema and ischemia.

PAPILLOPHLEBITIS(Optic disc vasculitis)

Healthy individuals, < 50 years Optic disc swelling with secondary

venous congestion rather than venous thrombosis.

APD absent, retinal haemorrhages confined to posterior fundus.

Prognosis: 80% -- 6/12 or better 20% visual loss -- macular edema

Management:Recent advances Recent onset of non-ischemic CRVO–

high intensity laser to create chorioretinal shunt.

AV sheathotomy for treatment of CME due to BRVO.

Ischemic CRVO:- PP Vitrectomy + Intraocular gas + Radial neurotomy

Management: Recent advances

Intravitreal tPA Transvitreal vein cannulation Section of posterior scleral ring Drug therapy -- Troxerutin

-- Petroxyfylline

-- Hemodilution Intravitreal Triamcinolone