Why does getting soap in your eyes cause redness and irritation?
This is because of the soaps chemical nature. They are alkaline agents and human eyes have a very low tolerance for alkalinity. Human eyes are roughly neutral with a pH of around 7, and soaps are around 7.5 to 9. 

The eye can't handle the alkaline object as it is potentially harmful to the eye so it will start watering to get rid of the alien substance. Blood vessels then enlarge, coming closer to the surface of the eye, making them appear red.

Most soaps are tested before released to make sure if they come into contact with eyes they are non-toxic. Baby soaps have a lower pH as well to make sure that the baby doesn't come to harm.

Either way, its probably best not to put it in your eyes.

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