I have noticed this happening to me quite alot recently. mainly in my peripheral vision. also a few wks ago when i was making tea my vision went all funny in my right eye like a shimmery sort of effect. it gradually got bigger and then i started to see loads of flashing colours then it moved around to my peripheral vision. it lasted for about 20 minutes then it went away. i went to the hospital as i was having a huge panic attack by this point and the doctor said every thing was fine. then about 10 minutes after i seen the doctor it happened again in my left eye but alot worse. i could hardly see at all and when it moved to my peripheral vision all i could see was bright red and blue. again it only lasted about 20 minutes. the doctor double checked my eyes for me to reassure me and said they are fine but i should see an optician. i still wasn't convinced though because the doctor didn't seem to know what was happening. i worry all the time that it is going to happen again.but i am starting to think now that maybe it is just my anxiety. i also worry that maybe i'm going to have a stroke or maybe i have a brain tumor as i also get shocks through my head.