Retinal artery occlusion (RAO) is blockage
of an artery
suppling oxygenated blood to the retina
of the eye,
resulting in reduced vision.
Note that a retinal artery occlusion is a type of
retinal
vascular occlusion (the other type of retinal vascular occlusion being
a retinal
vein occlusion).
Retinal artery occlusions are a moderately common type
of retinal vascular disorder.
It is useful to understand that there are two sources of blood supply
to the retina, i.e.
- supply through the choroid
- which is itself supplied via the ciliary arteries, and
- supply via the central retinal artery - which is from the ophthalmic
artery and splits into two equal superior (upper) and inferior (lower)
branches.
Depending on where in the retinal blood supply system the blockage
occurs, different parts of the retina can be affected (or unaffected).
Hence the severity of a retinal artery occlusion (RAO)
can vary considerably from case to case.
Retinal artery occlusions can be classified according
to the location of the blockage in the blood supply to the retina:
Types of retinal artery occlusions:
- Central retinal artery occlusion (CRAO)
- Branch retinal artery occlusion (BRAO)
- Cilioretinal artery occlusion.
Initial symptoms of retinal artery occlusion can include
a sudden loss of vision through one eye. In most cases the loss of vision
is severe, but not total. In a small proportion of cases, both eyes are
affected but not necessarily to the same extent.
Note that such symptoms alone are not sufficient to indicate retinal
artery occlusion (RAO).
As for all medical concerns, professional advice should be sought if and
when any problems arise - urgently if the issue is severe.
In many cases retinal artery occlusions are ophthalmic
emergencies, meaning that treatment must be given within a short time
of the apperance of initial symptoms in order for long-term deterioration
of sight (in the affected eye) to be avoided.
Retinal artery occlusions
are a large and complicated subject - with issues depending on the type
of retinal artery occlusion and its causes, and also
varying considerably from case to case.
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.
For further information see also our section of Books
about Ophthalmology. |
