system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If you have shampoo in your eyes, why does it only hurt when they're open?
gpt
Because your eyelids closing pushes the shampoo toward a central location. Now instead of having the entire surface area of your eye covered in shampoo, it’s just a smaller portion between your eyelids. This minimizes the pain.