Central Retinal Artery Occlusion

There is ongoing debate about the survival time of an ischaemic retina. A study on rhesus monkeys reported a retinal survival time of 105 minutes, [15] but other authors have suggested a beneficial effect from treatments given up to 24 hours after the onset of symptoms. [16]

Although in vivo animal experiments have suggested irreparable retinal damage after approx. 100 minutes, human studies have shown benefit of treatment up to 24 hours after the onset of retinal ischaemia.

Treatment

There is weak evidence for definitive treatment of this potentially catastrophic condition. A Cochrane review looking at all interventions for acute non arteritic CRAO found no high quality evidence to support routine use of any particular therapy. [17] However, expert opinion [5] suggests the following may be used in the ED.

Digital massage in the supine position

Ocular massage has been shown to cause retinal vasodilatation and large fluctuations in intraocular pressure, which have the potential to dislodge or disrupt an embolus in the central retinal artery. This is best performed by the patient if possible, to avoid iatrogenic injury through over-exuberant pressure. One suggested method is unilateral gentle palpation of one side of the affected eye, then the other side through closed lids. [18]

Increasing retinal perfusion pressure by reduction of intraocular pressure

Intravenous acetazolamide or mannitol are preferred for this treatment in the ED.

Selective intra arterial fibrinolysis

A meta-analysis has suggested some benefit, but specialist neuroradiological support is required.

Learning bite

Although definitive evidence is lacking, treatment for CRAO in the ED primarily consists of digital globe massage and pharmacological reduction of intraocular pressure.