Visual (Migraine) Aura
Many people get disturbances in their field of vision that can include:
These are known as visual auras and typically occur due to migraines.
Migraines are a neurological disorder that generally includes headaches. However, some people have 'silent migraines' - a migraine without a headache.
About 20% to 30% of patients with migraines experience visual auras.
The most common disturbance is a translucent semicircle with a jagged edge that starts to the left of center in the visual field. At first it is a barely noticeable obscuration with a shimmery, zigzag left margin. Within 10-20 minutes, it enlarges to occupy nearly half of the left hand side filed of vision. It is medically described as a 'scintillating scotoma' or 'fortification scotoma'. In those who suffer from head pain, the appearance of this aura often signals the of a migraine headache and as such acts as a sign to take preventative alleviating measures.
Visual auras are not harmful and they do eventually pass. How long they remain present varies from individual to individual. They do not require treatment.
Sometimes the flashing lights of visual auras can be confused with that of the flashing lights experienced in Posterior Vitreous or Retinal Detachment. One way of differentiating between the two is to cover each eye to check if the flashing lights are still visible. In migraines the flashing lights can still be seen regardless of which eye is covered, however in detachments, the flashing lights will only be seen in the one affected eye. If If uncertain, it is always advisable to have your eyes checked by your eye care professional.