system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is there something about soap in particular that makes it hurt more when it gets in your eyes?

I understand that eyes are sensitive organs and the body wants to protect them from pretty much everything, which is why we have eyelids and tear ducts and eyelashes. But it doesn't hurt all that much to open your eyes in water. Is there something in particular about soap, maybe its hydrophobic/hydrophilic nature or its basic PH that makes it hurt more?

Thank you, 

Signed: someone who got soap in their eye in the shower today.
gpt
Soaps are generally strongly basic, as bases are good for rendering the protein and fat molecules which we wash off plates and ourselves when cleaning. Breaking these molecules up allows them to be more easily wiped away. In addition, soap is a surfactant, which means it is capable of causing oil and water to mix by binding to both polar and nonpolar molecules. This means running water over a soap-soaked oil stain will remove it rapidly.

This is also why we use dish soap to clean wildlife in oil spills.

However, this is very unfortunate for your eyes, as the cell membranes in your corneal cells are also made of fats. Putting a dab of soap on them begins to literally render your eyes, which is incredibly painful specifically because that encourages you to dunk your head in water to wipe the soap off.