The zig-zag 'light' I see is similar to watching a lighted ferris wheel and the light goes around the perimeter of whatever I'm looking at. It is not always too noticible in bright daylight, but when I close my eyes, all I see is dark or course, with the lights revolving. Usually along with this comes blurred vision right in the centre of sight. Not long after this takes place, I get a very bad headache which can last for a day or more, even if I take medication for it.
This phenomenon started about 15 years ago, during a time when I was under a lot of stress at work, plus I had recently been diagnosed as being HIV+. I thought the problem could be related to the strong drugs I was taking for the HIV. The symptoms I described to the specialists lead them to believe that it was related to migraines (which I had never had before) and they did scans, blood tests etc. Migraine medication was prescribed and the next time these symptoms occurred, I took the meds prescribed. That led to an anxiety attack. Needless to say I threw that medication out.
Ever since that time, I have taken Tylenol or Advil immediately if I notice the blurred vision or the lightning. This appears to work and I don't get a migraine or if I do get a headache, it does go away in a short time.
At times, I have noticed that drinking red wine on an empty stomach, or eating Chinese food with Mono-Sodium-Glutamat (Natrium Glutamat)
can trigger these symptoms. Also using the PC for long periods of time and concentrating on doing something or times of stress can trigger this. At other times, there appears to be no reason for it.