Most vision disturbances associated with migraine — zigzag lines, flickering blind spots, shimmering arcs — happen in both eyes simultaneously, because they originate in the brain's visual cortex. Retinal migraine is different. It causes temporary visual loss or disturbance in one eye only, because it originates in the retina or the blood vessel supplying it.

This distinction matters clinically. While visual aura is a benign, well-understood neurological phenomenon, retinal migraine involves the eye's vasculature and carries a small but real risk of permanent vision damage with recurrent episodes.

What Is Retinal Migraine?

Retinal migraine (also called ocular migraine in some clinical contexts) is defined by the International Headache Society as a migraine subtype causing fully reversible monocular visual phenomena — including positive symptoms (flashing lights, zigzag patterns) or negative symptoms (partial or complete vision loss in one eye) — in association with a migraine headache.

Key criteria:

  • Visual symptoms affect one eye only
  • Symptoms are fully reversible and resolve within 60 minutes
  • Symptoms occur before or during the headache phase
  • No other eye disease or neurological cause accounts for the symptoms
  • The patient has migraine history

It is a rare diagnosis. True retinal migraine is estimated to affect fewer than 1 in 200 migraine patients. Many people who think they have retinal migraine actually have visual aura — the more common bilateral phenomenon originating in the brain.

The Simple Test: Cover One Eye

If you're experiencing a visual disturbance during a potential migraine episode, covering each eye in turn is a quick first assessment:

  • Visual aura (cortical): Disturbance persists regardless of which eye is covered, because it originates in the brain's visual processing area
  • Retinal migraine: Disturbance is present only when the affected eye is open and disappears when that eye is covered

This is an imperfect test in a moment of distress, but it's the most accessible way to distinguish retinal from cortical visual symptoms in real time.

Retinal Migraine Symptoms

During a retinal migraine episode, one eye may experience:

  • Scintillations — flickering, sparkly visual phenomena
  • Scotoma — a partial blind spot in the visual field
  • Monocular vision loss — partial or complete temporary blindness in one eye
  • Tunnel vision in one eye
  • Graying out or blackout of vision in one eye

These symptoms typically last 5 to 20 minutes and are followed by a headache. Complete recovery after each episode is part of the diagnostic criteria, but permanent vision loss — though uncommon — has been reported in patients with recurrent retinal migraine.

Mechanism: Vasospasm in the Retinal Artery

Unlike migraine with aura, which is caused by Cortical Spreading Depression in the brain, retinal migraine is thought to be caused by vasospasm — a temporary narrowing of the central retinal artery or one of its branches. This briefly reduces blood flow to part or all of the retina, causing the transient monocular visual loss.

The reason this is clinically significant is that repeated vasospasm can, over time, cause retinal infarction — a small area of permanent damage to the retina resulting in lasting visual field loss. This risk is considered low but is higher than the risk associated with typical visual aura.

When to Seek Urgent Care

Go to the emergency department or call emergency services if:

  • You experience sudden complete vision loss in one eye lasting more than 60 minutes
  • Vision does not fully recover after an episode
  • You develop new neurological symptoms — weakness, speech difficulty, facial drooping
  • You are over 50 with no prior migraine history
  • You have cardiovascular risk factors (hypertension, diabetes, smoking, atrial fibrillation)

Monocular vision loss can also be caused by central retinal artery occlusion (a medical emergency), amaurosis fugax (a TIA symptom), or detachment — none of which should be assumed to be retinal migraine without examination.

Diagnosis

Retinal migraine is diagnosed by a neurologist or ophthalmologist based on clinical history. You may be referred for:

  • Fundoscopy — examination of the retina, often normal between episodes
  • Fluorescein angiography — to assess retinal blood flow
  • OCT (optical coherence tomography) — to look for retinal thinning suggesting prior infarction
  • Neuroimaging — MRI to rule out cortical or vascular causes

A detailed log of each episode — which eye, what the visual disturbance looked like, duration, associated headache, and potential triggers — is invaluable for diagnosis.

Treatment and Prevention

Acute management: Most episodes resolve within an hour without intervention. Lying down in a dark room and taking an oral triptan (if tolerated) at onset may reduce the severity of the accompanying headache.

Preventive treatment: Due to the risk of retinal infarction with repeated episodes, most neurologists recommend preventive migraine therapy for patients with more than 2–3 retinal migraine episodes per year. Options include:

  • Calcium channel blockers (verapamil) — often preferred for retinal migraine due to their vasodilatory effects
  • Low-dose aspirin — antiplatelet therapy is sometimes recommended given the vascular mechanism
  • Beta-blockers — used cautiously (some forms can promote vasospasm)
  • Topiramate
  • CGRP monoclonal antibodies — emerging use

Important: Ergotamine derivatives and high-dose triptans (which cause vasoconstriction) are generally avoided in retinal migraine due to the risk of worsening vasospasm.

Triggers to address:

  • Oral contraceptives — estrogen-containing pills can promote vasospasm; discuss alternatives with your doctor
  • Smoking — strongly associated with retinal vascular events
  • Dehydration and skipped meals
  • Weather changes and other migraine triggers

Track your retinal migraine episodes carefully with Migraine Trail — logging which eye is affected, symptom duration, and any preceding triggers gives your specialist the precise data needed to guide treatment decisions.