Visual disturbances involving only one eye
Most of us are familiar with the term “aura” and understand it to be a visual disturbance that precedes the headache phase of a migraine attack. An aura often presents as wavy or zig-zag lines that spread across the visual field. Patients may also experience blind spots, flashing lights, auditory or olfactory hallucinations. An aura affects both eyes.
Not all migraine-related visual disturbances are an aura. In rare cases loss of vision or blind spots can affect only one eye. When this occurs, more serious causes of vision loss must be ruled out before concluding that the problem is a rare form of migraine called Retinal Migraine.
Retinal migraine has also been called “ocular” or “ophthalmic” migraine. Because these terms are not true diagnoses, they have also been used to refer to Acephalgic Migraine (i.e. “silent” migraine). Depending on the type of doctor and his or her qualifications, these terms are often interchangeable. The one thing each descriptor has in common is that it is used to describe a type of migraine that involves some kind of visual disturbance.
A true Retinal Migraine involves total or partial loss of vision in one eye. Vision returns to normal after 5-60 minutes. This visual disturbance is always followed by the headache phase. If you experience temporary vision loss in one eye without subsequent headache, then it is not Retinal Migraine and should be evaluated by an ophthalmologist. In the case of Ancephalic Migraine, if an aura is present, it will affect vision in both eyes.
Headache specialists use the International Classification of Headache Disorders (ICHD-3) to diagnose different types of migraine. If your doctor is not a headache specialist, he or she may offer you a descriptive diagnosis instead. A true Retinal Migraine is diagnosed when symptoms match the ICHD-3 criteria.
ICHD-3 Diagnostic Criteria - Retinal Migraine
Repeated attacks of monocular visual disturbance, including scintillations, scotomata, or blindness, associated with migraine headache.
A. At least two attacks fulfilling criteria B and C
B. Aura consisting of fully reversible monocular positive and/or negative visual phenomena (e.g. scintillations, scotomata or blindness) confirmed during an attack by either or both of the following: 1) clinical visual field examination, 2) the patient’s drawing (made after clear instruction) of a monocular field defect
C. At least two of the following three characteristics: 1) the aura spreads gradually over ≥5 minutes, 2) aura symptoms last 5-60 minutes, 3) the aura is accompanied, or followed within 60 minutes, by headache
D. Not better accounted for by another ICHD-3 diagnosis, and other causes of amaurosis fugax [loss of vision in one eye] have been excluded.
Some patients who complain of monocular visual disturbance in fact have hemianopia [blindness of half the visual field]. Some cases without headache have been reported, but migraine cannot be ascertained as the underlying etiology. Retinal migraine is an extremely rare cause of transient monocular visual loss. Cases of permanent monocular visual loss associated with migraine have been described. Appropriate investigations are required to exclude other causes of transient monocular blindness.
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