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Author: Fernando Pellerano, MS-V
Universidad Iberoamericana (UNIBE) School of Medicine
Retinal artery occlusion (RAO) is considered a true ophthalmic emergency requiring immediate assessment and initiation of treatment. Appropriate initial emergency management may be the most important factor in determining visual outcome.
RAO can either be central or branch. Central retinal artery occlusion (CRAO) results from a blockage anywhere between the origin of the artery (off the ophthalmic artery), to its first branch at the entry to the retina. The site of obstruction is therefore not generally visible on ophthalmoscopy and in most cases the entire retina is affected. Branch retinal artery occlusion (BRAO) occurs when the blockage is distal to the optic nerve, within the visible vasculature of the retina. A BRAO can involve as large an area as three quarters of the retina, or as small an area as just a few micrometers.
Epidemiology and Etiology
Incidence of RAO is approximately one per 100,000 per year and increases with age, peaking in the sixth and seventh decades. The central retinal artery is more commonly blocked than the branch retinal artery.  Although many systemic diseases are associated with RAO, more than 50 % of all affected patients will manifest no apparent systemic or local causes for the retinal disease. Possible Etiology and Risk Factors for both CRAO and BRAO are listed in Table 1 and Table 2.[3, 4]