i've decided i'm not allergic to the sun anymore, specifically in the sense that me seeing excessively bright lights will no longer give me headaches.
if my understanding is correct, the pain directly behind my eyes was never caused by optical overload, but rather by my reaction to it. my first response to bright lights is to tense some of the muscles in the area. after a while, these muscles started to hurt, which i interpreted as a sunlight-induced headache. in anticipation of these headaches, i learned to fear the sun and get all squinty with the least exposure.
this theory is based on a conversation i had with a uncle(cousin)-in-law who is a doctor and said that a normal healthy body will adapt to virtually any sensory input.
my first test of it was while walking home today. it was beautiful sunny walk, bright enough that i would normally wear my industrial strength sunnies that are just a step and a half shy of a welding mask. i felt my eyes instinctively try to tense up a few times, but i relaxed them (i don't really know how i relaxed them, since i don't even know what it was that was tense in the first place, but i relaxed them, nonetheless). this first test was a success.
with any luck, i'll have more chances to test the theory soon.