Retinal artery occlusion

Retinal artery occlusion (RAO) is blockage of an artery supplying 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.

1. supply through the choroid - which is itself supplied via the ciliary arteries, and
2. 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.

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 appearance 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 specialized source.