How does taking anti-inflammatory steroid medication affect the outcome of vision correction surgery?

It doesn't: Affect the result of the laser, but it does help the eye become less red and irritated after the surgery.

Well usually, : Anti inflammatory drops are used to slow or suppress the scarring (bad form of healing) reaction that can occur after refractive surgery. It can also alleviate discomfort. There are a wide variety of very effective steroid and non steroidal agents that can be used after refractive surgery.