What's going on?

The central retinal artery has been blocked by an embolus or some compressive/inflammatory process. The retina dies within approximately 90 minutes, with concomitant severe visual loss.

If I examine the patient what will I find?

The patient will have severe visual loss and RAPD. On fundoscopy, a pale white fundus with marked arteriolar attenuation and a cherry-red spot will be visible. An embolus may also be seen within the retinal vessels.

What if I've diagnosed it?

If the history is short (i.e., less than 24 hours), the patient should be referred immediately to the hospital eye services and assessed as soon as possible (immediately). If the history is more than 24 hours, the patient should be referred but assessment is less urgent (soon). If the duration of visual loss is more than a few days soon referral by letter is acceptable (soon via letter).

This can be a manifestation of GCA – if any features suggest this, the patient needs urgent referral.

What will the hospital do?

In acute cases, management will depend on the duration of the visual loss. If this is more than 24 hours, little is likely to be done as the prognosis is poor. If the history is less than 24 hours, attempts may be made to dislodge any embolus by dramatic reduction of the pressure inside the eye. This will be done medically or by needle aspiration of aqueous from the anterior chamber. In chronic cases the patient can develop rubeosis iridis, but this is rare.

GCA must be excluded unless there is an embolus obviously visible within the retinal vasculature. Patients over 50 years of age will have inflammatory indices measured.

What do I need to do?

Look for any source of embolus.

Is the patient in atrial fibrillation (AF?)
Is there a cardiac or carotid murmur?
Antiplatelet therapy is a sensible precaution against further embolic phenomena if there are no contraindications.
If there is a definite cardiac arrhythmia or valvular defect, then formal anticoagulation with warfarin may be indicated.
General cardiovascular risk factors should be addressed.

What do I tell the patient?

If there has been no recovery within 24–48 hours, the news is bad. The visual prognosis is poor and the likelihood of improvement is slim.

Problems that may arise, and how to deal with them

Other eye involvement is a great worry. As the patient has only one eye now, any problem with this good eye must be dealt with quickly.

There is also the possibility of new vessel formation and rubeotic glaucoma as a result of the ischaemia, although this is less common than with venous occlusive disease.