H34.831-833 Branch Retinal Vein Occlusion

A branch retinal vein occlusion (BRVO) is a common intraretinal vascular event.  It is caused by the occlusion of one of the branches of the central retinal vein, and is usually located distal to the central retinal vein’s bifurcation.

Although most branch vein occlusions occur in patients with systemic vascular disease, the events may occur spontaneously and without cause.

The pathogenesis of a branch retinal vein occlusion depends upon the vascular perfusion status.  For example, a non-ischemic occlusion occurs without interruption of vascular profusion.  Conversely, an ischemic occlusion is characterized by vascular stasis and the side effects of limited blood circulation.   

• Turbulent blood flow
• Damage to the vascular endothelium
• Thrombosis formation

Structural Damage to the Eye

• Retinal ischemia
• Macular edema

Functional Damage to the Eye

• None
• Loss of visual acuity is dependent on the amount of macular involvement

The main goal of the diagnostic evaluation for a patient with BRVO is to accomplish the following:

• Differentiate between ischemic and non-ischemic occlusions
• Determine the underlying systemic cause of the occlusion
• Prescribe a treatment plan

Patient History

Patients with BRVO will present with the following clinical symptoms or signs:

• Painless, gradual to sudden vision loss
• Visual disturbances such as flashes of light or floaters
• An abnormally intraocular pressure (IOP) will help differentiate BRVO versus ocular ischemic syndrome from a carotid occlusive disease.  Patients with ocular ischemic syndrome will have lower IOP than patients with BRVO
• Ischemic BRVO will have a relative afferent pupillary defect

DIAGNOSTIC TESTS

Refraction

• Measurement of visual function / visual acuity 
• Visual acuity of 20/400 or worse with correction along with signs of an afferent pupillary defect and visual field constriction are signs of an ischemic BRVO

Blood Pressure Measurement

• Systemic hypertension is a risk factor for branch retinal vein occlusion

Fundus Photography 

• To evaluate the optic nerve, macula and the retina

Extended Ophthalmoscopy 

• To evaluate the optic nerve, macula and the retina 

Visual Field Examination 

• Measurement of visual function

Macular OCT Scan

• Evaluate structural changes to the retinal and choroidal blood vessels

Gonioscopy

Any patient with a history of ischemic eye disease should receive a gonioscopic examination of the anterior chamber angle to look for any of the following:

• Fibrovascular membranes
• Neovascular blood vessels 
• Angle-closure

Iris Neovascularization Secondary to ischemic ocular disease

Systemic Evaluation

Eye doctors should consider a systemic evaluation in cases of branch retinal vein occlusion.  A typical investigative protocol would include the following tests: 

Blood Work

• Complete blood count (CBC)
• Westergren sedimentation rate (ESR)
• Lipid profile
• Fasting blood sugar/HbA1C
• Fasting treponemal antibody absorption test (FTA-Abs)
• Reactive plasma reagin (RPR)
• Homocysteine
• Protein S and C
• Lupus anticoagulant
• SickleDex
• Rheumatoid factor
• Purified protein derivative (PPD)
• Lyme titer
• Angiotensin converting enzyme (ACE)
• Antinuclear antibody (ANA)

Ancillary Testing

• Carotid Doppler
• Electrocardiogram (EKG)
• Chest X-ray

Retinal vein occlusions may be identified by their location in the vascular arcades:

• Superior temporal 
• Inferior temporal 

Ocular Ischemic Syndrome (Carotid Occlusive Disease) 

Patient will have dilated and irregular veins, but they will not be tortuous like in CRVO. Neovascularization is present in a third of patients, but disc edema and hemorrhage are not common.  Retinal hemorrhages are found in the mid-periphery of the retina.  There will be a history of transient ischemic attacks, amaurosis fugax and orbital pain. Intraocular pressures is usually low.

Diabetic Retinopathy 

The hemorrhages and microaneurysms are concentrated in the posterior pole and exudates are more common.  It is usually bilateral.

Papilledema 

There will be bilateral disc swelling with flame-shaped hemorrhages around the disc, but not into the peripheral retina.  Etiology is caused from increased intracranial pressure rather from a vascular etiology

Radiation Retinopathy 

There is a history of radiation therapy.  Patients will have disc swelling and retinal neovascularization, and cotton wool spots.

The goals of treating a branch retinal vein occlusion include the following:

• Differentiate the occlusion from ischemic vs. non-ischemic
• Treat any clinically significant secondary macular edema
• Identify the underlying systemic cause for the occlusion
• Treat the systemic disease in cooperation with internal medicine

Non-Surgical Treatment Guidelines

Observation for spontaneous resolution is an option in eyes with 20/40 vision or better.  Even in the presence of mild macular edema, some patients may decline intravitreal anti-VEGF injections or laser surgery.  In patients where observation is chosen as the initial treatment option, follow-up examinations may be performed at 3-month intervals. Non-surgical treatment involves close monitoring of the condition both on a home and clinical basis to maximize the earliest detection of further vision deterioration.  This is best accomplished by home Amsler grid testing and repeat ophthlalmoscopic evaluations including OCT analysis.

The patient in the photographs below is a 95-year-old black female who declined all surgical and pharmacologic intervention.

• Mild macular edema
• Retinal hemorrhage resolved over six months duration
• Distance visual acuity was never worse than 20/40 during the course of observation

Laser Therapy 

Laser photocoagulation is the treatment of choice in complications associated with retinal vascular diseases (i.e. diabetic retinopathy, branch retinal vein occlusion).  Panretinal photocoagulation (PRP) has been used in the treatment of neovascular complications of BRVO for a long time.  However, no definite guidelines exist regarding exact indication and timing of PRP. 

The patient in the photographs below is a 62-year-old black female with a six-month history of decreased vision in the left eye..

• Old branch retinal vein occlusion along the inferior temporal arcade
• 20/30 visual acuity 
• Normal Amsler grid testing
• No macular edema on OCT scan
• Several areas of neovascularization are present
• Laser surgery recommended to prevent secondary vitreous hemorrhage

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