branch retinal vein occlusion (brvo)

8/2/2019 Branch Retinal Vein Occlusion (BRVO)

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1Classification

Branch Retinal Vein Occlusion

Branch retinal vein occlusion (BRVO)CLASSIFICATION

1) Major BRVO: At the disc and/or away from the disc.

2) Macular BRVO: Involving only a macular branch.

3) Peripheral BRVO: Not involving the macular circulation.

DIAGNOSIS

Presentation:

It depends on the extent of macular circulation compromised by the occlusion.

Patients with macular involvement often present with the sudden onset of blurredvision and metamorphopsia, or a relative visual field defect.

Patients with peripheral occlusions may be asymptomatic.Visual Acuity (VA):It is very variable and is principally dependent on the extent of macular involvement.

Fundus Examination:

Dilatation and tortuosity of the affected venous segment. The site of occlusion is often identifiable as an arteriovenous crossing point. Flame-shaped and dot/blot haemorrhages, retinal edema, sometimes cotton wool spots

affecting the sector of the retina drained by the obstructed vein.

Fluorescein Angiography (FA):

It shows variable delayed venous filling, blockage by blood, staining of the vessel wall,

hypofluorescence due to capillary non-perfusion and pruning of vessels in the ischemic areas.

Optical coherence tomography (OCT):

It demonstrates and allows quantification of the severity of macular edema and is a useful way

of monitoring its course and the response to treatment.


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2Prognosis


Course:

The acute features usually resolve within 612 months and may be replaced by the following:

Exudates, venous sheathing and sclerosis peripheral to the site of obstruction,collaterals and variable residual haemorrhage.

Collateral are characterized by slightly tortuous veins that develop locally or across thehorizontal raphe between the inferior and superior vascular arcades and are best

detected on FA.

The severity of residual signs is highly variable and they may be only subtle.

PROGNOSIS

At 6 months about 50% of eyes achieve vision of 6/12 or better.

Approximately 50% of untreated eyes with BRVO retain 6/12 or better whilst 25% willhave vision of


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3Management


MANAGEMENT

Follow-up should be at about 3 months with FA:

A) With good macular perfusion and improving visual acuity, no treatment is required.

B) If macular edema is associated with good macular perfusion and visual acuity continues to be

6/12 or worse after 36 months, laser photocoagulation should be considered. Patients with

visual acuity of less than 6/60 or those with symptoms for over a year are unlikely to benefit

from laser. Prior to treatment, the FA should be studied carefully to identify leaking areas.

C) If macular non-perfusion is present and visual acuity is poor, particularly if FA shows an

incomplete foveal avascular zone (FAZ), laser treatment is unlikely to improve vision.

Treatment of macular edema

Grid laser photocoagulation

(50100 m, 0.1 second duration and spaced one burn width apart) to produce a gentle

reaction in the area of leakage as identified on FA. The burns should extend no closer to the

fovea than the edge of the FAZ and be no more peripheral than the major vascular arcades.

Care should be taken to avoid treating over intraretinal haemorrhage. It is also very important

to identify shunts/collaterals on FA, which do not leak fluorescein, because they must not be

treated. Follow-up should take place after three months. If macular edema persists, re-

treatment may be considered although the results are frequently disappointing.

Intravitreal triamcinolone (IVT)

It is as effective as laser in eyes with macular edema, but may cause cataract and elevation of

intraocular pressure. An average of 2 injections of 1 mg are given in the first year.

Periocular steroid injection

It is less invasive, although probably less effective, than the intravitreal route.

Intravitreal anti-VEGF agents.

Bevacizumab (Avastin) 0.05 mL/1.25 mg) in a regimen of 23 injections over 56 months has

shown promising effects on macular edema and vision, including in patients resistant to laser.


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4Management


Arteriovenous sheathotomy.

Some positive results have been reported both for sheathotomy and for vitrectomy alone; a

randomized controlled trial showed similar benefit from IVT.

Treatment of neovascularization

Neovascularization is not normally treated unless vitreous haemorrhage occurs because early

treatment does not appear to affect the visual prognosis.

If appropriate, scatter laser photocoagulation (200500 m size, 0.050.1 s duration and

spaced one burn width apart) is performed with sufficient energy to achieve a medium reaction

covering the entire involved sector as defined by the colour photograph and FA. A quadrant

usually requires 400500 burns. Follow-up should be after 46 weeks. If neovascularization

persists re-treatment can be considered, and is usually effective in inducing regression.

branch retinal vein occlusion (brvo)

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