A retinal artery occlusion is a blockage of the artery supplying blood to the retina. Retinal tissue deprived of blood is injured within a short period, and vision loss is typically sudden, painless and profound.

It is treated as a medical emergency — not only because of the eye, but because the same process that blocked the retinal artery can block an artery in the brain.

This is an emergency. Go to the emergency room.

Sudden, painless loss of vision in one eye requires immediate emergency evaluation — call 911 or go to the nearest emergency department. Do not wait for an eye appointment, and do not wait to see whether vision returns on its own.

The reason is that a retinal artery occlusion carries a substantially increased short-term risk of stroke. The workup that follows — imaging of the carotid arteries, cardiac evaluation, assessment for giant cell arteritis in older patients — is time-sensitive and is performed in a hospital setting, not in an eye clinic.

Brief episodes of vision loss that resolve within minutes (amaurosis fugax) carry the same implication and warrant the same urgency, even though sight has returned.

What patients experience

  • Abrupt, painless loss of vision in one eye, often described as a curtain falling or as everything going gray or black
  • Loss of a portion of the visual field, if a branch artery rather than the central artery is blocked
  • Temporary loss of vision lasting seconds to minutes, then full recovery

There is characteristically no pain, no redness and no discharge. The absence of pain is one reason patients sometimes delay seeking care, and it is precisely why the guidance is to treat painless vision loss as more urgent, not less.

Central and branch occlusions

A central retinal artery occlusion (CRAO) blocks the main artery supplying the retina, and vision loss in that eye is usually severe and involves the whole field.

A branch retinal artery occlusion (BRAO) blocks a smaller tributary. Loss corresponds to the area that artery supplied, so patients may notice a distinct missing wedge or half of their vision while the remainder is unaffected.

The blockage most commonly results from an embolus — a fragment of cholesterol plaque, calcium or clot — that has traveled from the carotid artery or the heart. Less commonly it results from inflammation of the artery wall, as in giant cell arteritis, which requires urgent treatment of its own.

Evaluation in the eye and beyond it

Examination of the retina shows a pale, swollen retina with a characteristic appearance at the macula in central occlusions, and an embolus is sometimes directly visible within a vessel. Optical coherence tomography documents retinal swelling and later thinning, and fluorescein angiography can confirm the interruption in blood flow.

The systemic evaluation is at least as important. It typically includes carotid imaging, cardiac assessment including rhythm monitoring for atrial fibrillation, blood pressure, glucose and lipid measurement, and — in patients over roughly 50 — urgent blood tests for giant cell arteritis, since untreated arteritis can affect the second eye within days.

Treatment and what follows

Treatment of the eye itself is limited, and no intervention is reliably effective once retinal tissue has been deprived of blood supply. Various measures have been attempted to dislodge an embolus or improve perfusion, and their value remains uncertain; where they are considered at all, they are considered within a narrow window after onset. Your physicians will explain what, if anything, applies to your situation.

The substantial part of management is therefore preventive: identifying and treating the source of the embolus to reduce the risk of stroke and of an event in the other eye. That may involve antiplatelet or anticoagulant therapy, treatment of carotid disease, management of atrial fibrillation, or corticosteroid treatment where giant cell arteritis is confirmed.

Ongoing eye follow-up watches for abnormal new vessel growth, which can develop in the weeks after an occlusion and may require laser or injection treatment.

Retinal artery occlusion: questions and answers

The mechanism is the same as a stroke — a blocked artery depriving tissue of blood supply — with the retina affected instead of the brain. The term is useful because it conveys the urgency and the fact that the underlying cause is a circulatory problem, not a problem confined to the eye.

Yes, urgently. A temporary episode of vision loss suggests an embolus that passed through, and it carries a significantly raised risk of a stroke in the following days. Recovery of vision is not reassurance and should not delay emergency evaluation.

Recovery after a central retinal artery occlusion is uncommon, though some patients regain a degree of vision, and branch occlusions may leave much of the visual field intact. What is realistic in your case depends on the type of occlusion and how long the retina was affected, and is best discussed once your examination and imaging are complete.

The underlying condition — carotid disease, cardiac disease or arteritis — can affect the other eye, which is why identifying and treating the source is the priority. In giant cell arteritis in particular the second eye can be affected quickly, and that is why urgent testing and treatment are part of the emergency workup.

The emergency department. The immediate priority is the stroke workup and, in older patients, excluding giant cell arteritis — both of which need hospital resources. Eye follow-up is arranged afterward.

After the acute evaluation, follow-up monitors for abnormal new blood vessel growth on the retina or iris, which can develop weeks later and raise eye pressure. These are treatable when identified early, which is why examinations continue even when vision is not expected to change.

Sudden painless vision loss is an emergency

If you are experiencing sudden loss of vision in one eye, call 911 or go to the nearest emergency department now. For follow-up retina care afterward, Retina Macula Institute of Arizona can be reached at (602) 613-5473.