Sudden, painless loss of vision in one eye is an emergency. Go to the nearest emergency department or call 911. Do not wait for an office appointment. A retinal artery occlusion is treated in the same time-critical way as a stroke.
What it is
The retina is fed by the central retinal artery, which enters the eye through the optic nerve and branches out across the retinal surface. When one of these vessels is blocked — usually by a small clot or a fragment of cholesterol plaque that has traveled from the carotid artery or the heart — the retina downstream of the blockage is deprived of oxygen and stops working within minutes.
If the main trunk is blocked, this is a central retinal artery occlusion and vision in that eye drops profoundly. If a single branch is blocked, it is a branch retinal artery occlusion, and the loss is confined to the part of the visual field served by that branch.
Symptoms
- Sudden, painless loss of vision in one eye, over seconds
- Loss of one section of the field of vision — often the upper or lower half — in a branch occlusion
- Sometimes preceded by episodes of temporary vision loss lasting minutes and then clearing (amaurosis fugax), which is itself an urgent warning sign
Why it is an emergency
Two reasons, and both are about more than the eye.
Stroke risk. A retinal artery occlusion is a stroke. The same embolus that lodged in the eye could have lodged in the brain, and the risk of a brain stroke is highest in the days immediately afterward. Current guidance is for patients to be evaluated urgently in a stroke center setting — brain imaging, carotid imaging, cardiac evaluation and rhythm monitoring, and review of blood pressure, cholesterol, and diabetes control. This evaluation is the single most valuable thing that happens after an artery occlusion.
Giant cell arteritis. In patients over about fifty, an artery occlusion can be caused by giant cell arteritis, an inflammation of medium-sized arteries. This is treatable with high-dose steroids, and treating it promptly protects the other eye, which is otherwise at real risk over the following days. Tell us or the emergency physician if you have had new headaches, scalp tenderness, jaw aching while chewing, fever, weight loss, or aching in the shoulders and hips. Blood tests are checked urgently in this situation.
How we diagnose it
The diagnosis is made on dilated examination, where the affected retina appears pale and swollen and a cholesterol or fibrin plug may be visible in a vessel. We confirm and document it with OCT imaging, and sometimes with fluorescein angiography or OCT angiography to map exactly which vessels are not perfusing.
Treatment
There is, at present, no reliably effective treatment that restores vision once the retina has been without blood flow. Retinal tissue is injured within roughly ninety minutes, and most patients reach care after that window. A number of maneuvers have historically been tried — ocular massage, lowering the eye pressure, breathing carbon dioxide mixtures — and clot-dissolving therapy is being studied in clinical trials, but none is established as standard care. We will be honest with you about what is realistic for the affected eye.
What we do treat actively is what comes afterward. A minority of eyes go on to develop abnormal new blood vessels on the retina or the iris weeks to months later, which can cause a painful, sight-threatening rise in eye pressure. We monitor for this and treat it when it appears with intravitreal injections and panretinal photocoagulation.
Protecting the other eye — and you
The priority after an artery occlusion is preventing the next event. That means completing the vascular workup, and then staying on top of blood pressure, cholesterol, blood sugar, and any prescribed blood thinner or antiplatelet medication, and stopping smoking. We work alongside your primary care physician, neurologist, and cardiologist, and we will keep seeing you to watch the affected eye for late complications.