Branch retinal artery occlusion (BRAO) usually results from occlusion of a division of the retinal artery due to embolism leading to sudden segmental visual loss.

Retinal opacification in the distribution of the affected vessel caused by infarction of the inner retina along with retinal whitening cotton wool spots (CWSs) can be seen on fundus examination in the acute phase. A Hollenhurst plaque may be visualized at the site of occlusion.

Fluorescein angiography (FA) usually demonstrates a capillary nonperfusion in the distribution of the occluded artery.

Acute BRAO is characterized by significant increased hyperreflectivity inner retina including inner nuclear, inner plexiform, and ganglion cell layers, as a hyperreflective band with possible mild increased thickness, which is contrasted by the normal corresponding layers of the unaffected macula¹ (Figure 11.1).

Paracentral acute middle maculopathy (PAMM) that is seen in central retinal artery occlusion (CRAO) may also be seen in BRAO indicating deep capillary ischemia² (Figure 11.2).

In chronic BRAO, optical coherence tomography (OCT) can be a great toll in diagnosing inner retinal atrophy corresponding to thinning and loss of the inner retinal layer architecture (Figures 11.3 and 11.4).