I was just doing some research and found this post! My niece and nephew were just complaining of this to me and I'm trying to convince them to try Buteyko
Peripheral neuropathy can be the result hyperventilation. And Peripheral neuropathy can result in flashes of light
“When the peripheral nerves are damaged, the electrical system goes haywire. Sometimes there are sparks, and sometimes the lights go out.”
Only it's not permanent nerve damage if it is from hyperventilation. I used to have flashes of light and blurred vision quite bad. But have not for a couple of years.
If you still have them.... try measuring your Control Pause as an indication of how much you are hyperventilating.