2CLASSIFICATION BRVO CRVO Major BRVO Non-ischemic Minor Macular BRVO IschemicPeripheral BRVO PapillophlebitisHemiretinal Vein occlusion
3PATHOGENESIS Arteriosclerosis Compression of the vein Venous endothelial cell lossThrombus formationVenous Occlusion
4PATHOGENESIS Venous occlusion elevation of venous & capillary pressure Stagnation of blood flow Increased tissue pressure Hypoxia of the retinaDamage to capillary endothelial cells &extravasation of blood constituents
5RISK FACTORS (in order of importance) Advancing age: 50% cases over 65 yrs.Systemic: HT, Hyperlipidemia, Diabetes, Smoking, Obesity.Raised IOP: risk of CRVOInflammatory: Behcet’s, Sarcoid,AIDS, SLE, Toxoplasma.Hyperviscosity: Polycythemia, MM, Waldenstrom macroglobulinemia.
6RISK 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
12Prognosis and Complications of BRVO Depends on • Site & Size of occluded vein • Integrity of perifoveal capillary network50% : Recover VA of 6/12 or better.Complications: 1. Chronic macular edema2. Macular ischemia3. Neovascularisation,NV (within 3 yrs)10%- NVD, 20-30%- NVE4. Recurrent VH, TRD.
16Management 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 months.Neovascularisation– scatter laser
23Non-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.
24Ischemic CRVO: Management (CVOS) Follow-up: monthly for 6 monthsIOP, 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.
25Hemiretinal vein occlusion Less common than BRVO and CRVOOcclusion of superior or inferior branch of the CRV.Features of BRVO, involving the superior or inferior hemispherePrognosis depends on severity of macular edema and ischemia.
26PAPILLOPHLEBITIS (Optic disc vasculitis) Healthy individuals, < 50 yearsOptic disc swelling with secondary venous congestion rather than venous thrombosis.APD absent, retinal haemorrhages confined to posterior fundus.Prognosis: 80% -- 6/12 or better20% visual loss -- macular edema
27Management: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