system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5; Why/ how do our eyes interpret bright light as painful?

For example being used to a dark room, and then walking into another that's much brighter and having a pain response while adjusting to the new lighting.
gpt
In a dark room, our pupils dilate to let in more light so we can see better. Pupils also constrict in a bright room to help cut down the amount of light going to the retina. If you go from a dark room to a light room, your dilated pupils let in a large amount of light which damages the retina because of how sensitive they are.