| Branch Retinal Vein Occlusion |
What is a branch retinal vein occlusion?
Branch retinal vein occlusion is a condition in which part of the
venous drainage system of the retina is blocked. The retinal artery
supplies blood to the retina. The blood flows through retinal
arterioles, capillaries and finally through branch retinal veins that
drain into the central retinal vein. A blockage in one of these branch
retinal veins causes back pressure and leads to hemorrhage, exudation,
and/or decreased blood flow in the area of the retina drained by that
particular branch retinal vein.
How does branch retinal vein occlusion affect the vision?
Branch retinal vein occlusion can affect the vision in a number of
ways. Poor blood flow (ischemia) through the center of the retina
(macula) can severely decrease the vision. Additionally, exudation and
bleeding from the capillaries can cause swelling in the macula (macular
edema) which also leads to visual loss. Poor blood flow can also lead
to development of abnormal new vessels (neovascularization) not only in
the retina but also in the front part of the eye (rubeosis iridis).
These new vessels can lead to development of bleeding in the eye
(vitreous hemorrhage) and/or increased eye pressure (neovascular
glaucoma). Rarely, scar tissue can form on the surface of the macula
causing macular pucker formation. Another rare complication is the
development of retinal detachment.
Who is at risk of developing branch retinal vein occlusion?
Branch retinal vein occlusion typically occurs after age 50 with peak
incidence between age 50 and 70. An increased risk for development of
branch retinal vein occlusion is demonstrated in individuals with a
history of systemic hypertension, history of stroke or coronary artery
disease, history of smoking, a history of glaucoma, and a history of
elevated homocysteine. Rarely, blood clotting abnormalities,
medications (e.g. birth control pills) or certain types of uveitis can
predispose to the development of branch retinal vein occlusion.
What is the risk to the other eye?
Almost 10% of patients with branch retinal vein occlusion develop a
central retinal vein occlusion or branch retinal vein occlusion in the
other eye.
How is branch retinal vein occlusion treated?
The
diagnosis of branch retinal vein occlusion can easily be made on
clinical examination. However, in the first three to six months
following branch vein occlusion, significant intraretinal hemorrhages
can make it difficult to predict the clinical course and visual
outcome. A fluorescein angiogram is usually performed to look for areas
of abnormal leakage or poor blood flow within the macula. If the
macular blood flow is poor, the chances of visual improvement are more
limited. Ocular coherence tomography (OCT) is also often performed to
evaluate and quantitate the amount of macular edema. If there is
abnormal leakage but the blood flow is reasonable, laser treatment can
be performed to the areas of abnormal leakage. Laser treatment has been
shown to be helpful in improving vision and has been the standard
treatment for the last 20 years. More recently injection into the eye
of a small amount of steroid (Intravitreal Kenaolog) has been shown in
small studies to reduce macular edema and improve vision. In some cases
surgical separation of the “Stiff” artery that is pinching off the vein
to cause the blockage is inicated and can be performed (sheathotomy).
These treatment may be used in combination. The laser is the standard
treatment with the latter two being promising techniques that have yet
to be completely studied in a controlled randomized fashion.
If abnormal new vessels (neovascularization) develop, laser
treatment is indicated to cause regression of these abnormal vessels.
For persistent vitreous hemorrhage, retinal detachment or macular
pucker formation, surgery might be necessary. |
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