Hello and welcome to the zero to finals podcast.

My name is Tom and in this episode I'm going to be talking to you about central retinal artery occlusion.

And you can find written notes on this topic at zero to finals.com slash central retinal artery occlusion or in the ophthalmology section of the second

edition of the zero to finals medicine book. And you can find flashcards and questions to train your

knowledge and help you remember this information for longer at members.0.0.com. So let's get straight into it.

Central retinal artery occlusion occurs due to obstruction to blood flow through the central

retinal artery. The central retinal artery is a branch of the ophthalmic artery, which is a branch of the internal carotid artery.

The most common cause is atherosclerosis.

It can also be caused by giant cell arteritis, where vasculitis affecting the ophthalmic or central

retinal artery reduces the blood flow.

Let's talk about the risk factors.

The risk factors for cardiovascular disease, for example smoking, hypertension, diabetes

and raised cholesterol, increased the risk of atherosclerosis and central retinal artery occlusion.

The risk factors for giant cell arteritis are white ethnicity, older age, female, and polymyalgia rheumatica.

Let's talk about the presentation.

Blockage of the central retinal artery causes sudden painless loss of vision.

It may be described as like a curtain coming down over the vision.

On examination, there will be a relative afferent pupillary defect, where the pupil in the

affected eye constricts more when light is shone in the other eye than when it's shone in the

affected eye.

The light input is not sensed by the ischemic retina when testing the direct light reflex, meaning that shining

a light in the affected eye does not cause pupil constriction. But the light is sensed by the

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