Same! My understanding of migraines is that it's something to do with blood pressure in your head. My hypothesis is that the visual disturbances are your blood vessels dilating and pressing against your retina. Then I think it can cause kind of a runaway feedback loop of some sort that causes the blood pressure to increase throughout your head, causing pain.
Thinking about it now, I wonder if the light trigger could be the bright light causing minor damage to your retina, potentially triggering an inflammation/repair response. The fact that it happens when going from dark to light suddenly, also makes sense, since your pupil is at its most dilated when in the dark, meaning the most of your retina is exposed/vulnerable. That might also explain why it always starts in the periphery; because the edges of your retina are likely less often exposed to light and potentially more delicate -- but would be exposed if you see bright lights while your pupils are fully dilated.
For me, I've found it's also closely related to irregular food or sleep. And I find eating something with sugar or drinking some water can reduce the likelihood of the visual disturbances becoming a full-on migraine. My hypothesis is that these things alter your blood chemistry/physics enough to interfere with the runaway feedback loop that results in increasing blood pressure. I imagine dunking your head in cold water likewise works because it breaks the runaway process.
Thinking about it now, I wonder if the light trigger could be the bright light causing minor damage to your retina, potentially triggering an inflammation/repair response. The fact that it happens when going from dark to light suddenly, also makes sense, since your pupil is at its most dilated when in the dark, meaning the most of your retina is exposed/vulnerable. That might also explain why it always starts in the periphery; because the edges of your retina are likely less often exposed to light and potentially more delicate -- but would be exposed if you see bright lights while your pupils are fully dilated.
For me, I've found it's also closely related to irregular food or sleep. And I find eating something with sugar or drinking some water can reduce the likelihood of the visual disturbances becoming a full-on migraine. My hypothesis is that these things alter your blood chemistry/physics enough to interfere with the runaway feedback loop that results in increasing blood pressure. I imagine dunking your head in cold water likewise works because it breaks the runaway process.
But this is all speculation.