Common Eye Conditions

Migrain

Briefly:

Visual symptoms often precede a migraine, they cause no lasting damage to the vision.

Fuller Explanation:

There are many types and severity of migraine symptoms. When there are visual symptoms they generally precede the headache and are called prodromal symptoms.

The three most commonly reported visual disturbances are a flashing zigzag light, part of the vision (often the centre portion or the right or left hand side) disappears or people reporting that it looked as if they were looking through a waterfall or heat haze. These disturbances typically last for approximately twenty minutes then go and the headache follows (varying in intensity from feeling a slight muzziness to debilitating).

The cause of the visual disturbance is due to errors in the way the brain
processes the visual inputs and is thought to be caused by vascular spasms. Normally the brain receives millions of nervous impulses every second from the eyes, these impulses are in actual fact tiny electrical pulses.

The brain deciphers these impulses to create a picture of what we are looking at. When we experience prodromal symptoms it is as if there is extra, errant electrical activity going on in the brain and the brain thinks; this is the message I get when I am looking at a flashing light or through a waterfall etc. and so superimposes that image over what you are actually looking at. This explains why the disturbance to the vision is ‘seen’ with both eyes even if it appears to be on one side, and in fact is still ‘seen’ when the eyes are closed. It is not seen with the eyes but is ‘made up’ by the brain. When the visual symptoms stop there is absolutely no long term damage to the visual system.