Ocular Ischaemic Syndrome

Ocular ischaemic syndrome (OIS) refers to chronic ocular hypoperfusion usually secondary to severe atherosclerotic carotid stenosis on the same side. It is important to note however that any disease causing decreased flow through the carotid artery could potentially cause OIS. Other conditions may include carotid artery dissection, giant cell arteritis, aortic arch syndrome, Behcet’s disease, trauma or inflammation (Terelak-Borys et al 2012, Malhotra and Gregory-Evans 2000)

OIS is a rare but vision-threatening condition.

Stenosis of the carotid artery results in reduced perfusion pressure in the central retinal artery, leading to ischaemia and associated complications over time, including neovascularisation (retina, disc and/or iris).

Vision loss is a key presenting symptom of this condition however the rate of vision loss is quite variable - 67% of patients note gradual loss over a few weeks or months, 12% note the change over several days, and 12% note sudden vision loss over a period of minutes or seconds (Mendrinos et al., 2010). The extent of vision loss and presence and type of visual field defects is variable. 13% of patients with OIS report pain (Mizener,1997) and they may find this is relieved by laying down.

In approximately 66% of patients, neovascularization of the iris and/or angle can be identified. This may be the only sign of OIS in some patients, and can lead to neovascular glaucoma and, eventually, a sore eye with no light perception.

Posterior signs include narrowing of the retinal arteries and dilation of the retinal veins (although both may be narrowed in some cases). Microaneurysms and retinal haemorrhages are typically seen in the mid-periphery. Macular oedema may be present.

Terelak-Borys, B. Skonieczna, K. Grabska-Liberek, I. (2012) Ocular ischemic syndrome – a systematic review Med Sci Monit. 18(8): RA138–RA144.