Retinal vein occlusion (RVO) is the blockage
vein carrying de-oxygenated blood from the retina
of the eye
(back towards the heart
for oxygenation), resulting in reduced vision.
The reduction in vision can be severe and occurs because blockage of the
vein results in some blood leaking out of the vein itself - into the surrounding
tissues. Clear fluid also leaks out into the tissues of the retina, effectively
‘water-logging’ it so that the image formed on the retina
is not transmitted clearly to the brain - hence the images normally called
"sight" are not received /perceived.
Note that a retinal vein occlusion is a type of
vascular occlusion (the other type of retinal vascular occlusion being
Retinal vein occlusions are a moderately common
type of retinal vascular disorder.
They can occur at almost any age (but most often in middle-age and beyond).
There is a huge range in severity - from barely perceptible to
painful with loss of sight in affected eye.
Types of retinal vein occlusions:
- Central retinal vein occlusion (CRVO)
- non-ischaemic - milder form, approx. 75% of CRVOs. May resolve
fully with good visual outcome - or progress to the ischaemic type.
- ischaemic - severe form, may result in neovascular glaucoma and
a painful blind eye.
- Branch retinal vein occlusion (BRVO)
- 3x more common than CRVOs.
- Several subclassifications of BRVO, according to whether a major
branch, a minor macular branch or a peripheral branch is affected.
- Hemiretinal vein occlusion
- May be inferior (lower-half of the visual field in the affected
eye) or superior (upper-half of the visual field in the affected
Retinal vein occlusions
are a large and complicated subject - with symptoms, management/treatment,
possible complications, and outcomes varying according to the type of
retinal vein occlusion and also varying considerably
from case to case - note the range in severity mentioned above.
This brief entry is included for completeness
to mention a wide range of ophthalmic conditions in this section - for
more information ask an expert or consult a more specialised source.
More about Ophthalmology: This section includes short definitions
of many diseases, disorders, and conditions of the eyes and visual system.
For definitions of other terms in this category, choose from the list
to the left (but note that this is not a complete/exhaustive list).
Other related pages include the diagram
of the eye, and definitions
of parts of the eye, a description
of the human retina, and definitions
of parts of the retina, and the section of short definitions
of clinical and surgical procedures re. eyes and human visual system.
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