I also experience a bit of anxiety from lights that are too bright, shopping malls etc...
I think its very common in people with Anxiety. What happens to your visions is just the effects of anxiety taking control. The more you expose yourself to those feelings the better they should be.
Call me daft but what does GAD mean??? Anyway i suffer from bouts of anxiety and stress and i do have lightsensitivity i have to weat sunglasses when ever sun is out and this screen is also too bright, everytime i come on it i keep thinking i need one of them screen covers i can feel my eyes scruching up, certain lights especially them tube ones do my eyes in, they make me go funny. I used to think it was due to my light coloured eyes but now i do think it may run in the family as my children are the same, they will scream when out is sun saying too bright, and head lights in car look extremely dazzling when i can't wear sunglasses : (