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Branch Retinal Arterial Occlusion (BRAO)

​Causes

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  • Majority of cases result from emboli

  • Causes of emoblic BRAO:

    • cholesterol - from disease in the carotid arteries

    • fibrin platelet clots - from disease in the carotid arteries

    • calcific embolus - from disease of the cardiac valves

    • blood clots resulting from antiphospholipid syndrome ​​

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Presentation

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  • sudden, painless unilateral visual field defect

    • altitudinal defect - this means there is loss of vision either in the upper half or lower half of the vision, but it does not cross the horizontal midline

  • Visual acuity may be reduced if the central vision is affected

    • otherwise patient may not notice any symptoms​

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Examination

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  • Arterioles and venules may be attenuated (narrowed)

    • can sometimes see segmentation of affected arterioles and veins, known as 'cattle trucking' - instead of being a continuous line, the vessels have breaks in them

      • said to resemble a single-file line of cattle ​

  • Retina surrounding a branch retinal arteriole appears pale and swollen

  • Culprit embolus may be visible within affected arteriole 

  • Normally there is a pinkish-orange colour to the retina due to the choroidal circulation that lies underneath, as the retina is transparent

    • when ischaemic, the retina becomes less transparent and thickens; gives it a white appearance around the affected branch retinal arteriole 

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Treatment

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  • there is no specific treatment available for BRAO

  • if patient presents within 24h of onset of symptoms, should attempt: 

    • ocular massage

    • patient to breathe in and out of a paper bag - aims to increase CO2 levels to cause vasodilatation of retinal vessels to overcome vessel occlusion

    • ocular paracentesis - needle used to remove fluid from anterior chamber and reduce intraocular pressure (IOP)

    • IV acetazolamide - to reduce IOP

  • should have repeat review 3 months after episode

  • any other systemic disease related to the BRAO (antiphospholipid syndrome, carotid artery disease) should be managed appropriately

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References

  • Denniston, A. K. O. and Murray, P. I. (eds) (2018) Oxford handbook of ophthalmology. 4th edn. London, England: Oxford University Press (Oxford Medical Handbooks). doi: 10.1093/med/9780198804550.001.0001.

  • James, B., Bron, A. J. and Parulekar, M. V. (2016) Lecture Notes Ophthalmology. 12th edn. Nashville, TN: John Wiley & Sons (Lecture Notes)

  • Salmon, J. F. (2019) Kanski’s clinical ophthalmology. 9th edn. London, England: Elsevier Health Sciences.

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