Branch retinal artery occlusion
 

Branch retinal artery occlusion showing multiple shiny multiple cholesterol emboli An embolus from a calcific plaque at the  bifurcation of the superior artery. The colour of  the plaque is nearly identical to the optic disc and  a casual examination may miss the sign.

In the examination you are unlikely to get a case of cherry red spot from central retinal artery because the sign  usually disappears after 72 hours. Most cases of central retinal artery will be presented as optic atrophy or relative  afferent pupillary defect. On the other hand, signs from emboli tend to remain longer and therefore more likely to  appear in the examination. The retinal artery shows cattle-trackings with multiple emboli. The emboli may be shiny if due to cholesterol crystals (Hollenhorst plaque). In early stage, the retina may show retinal oedema. Mention that you would like to: perform a cardiovascular examination including listening for carotid bruit on the ipsilateral side.

Questions:

1. What are the types of emboli which can cause branch retinal artery occlusion?

Answer
Three main types of emboli are:
cholesterol crystals arising from the carotid arteries
platelet-fibrin emboli associated with large vessel arteriosclerosis
calcific emboli arising from diseased cardiac valves
Rare causes include cardiac myxoma, fat emboli from long bone fracture or septic emboli.

2. What is the significance of cilioretinal artery in central retinal artery?

Answer
The cilioretinal artery arises from posterior ciliary circulation. It supplies a variable part of the macula and in the presence of central retinal artery occlusion. The central vision may be spared to such an extent that the patient may retain 6/6 vision.

3. What is the incidence of neovascularization in central retinal artery occlusion?

Answer
Compared with central retinal vein occlusion, neovascularization is uncommon. It is seen in about 5% of the cases. Treatment is with pan-photocoagulation as in central retinal vein occlusion.

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