Tonight on Grey's Anatomy, Meredith begins to develop problems with her eyesight, ones which reportedly stem from her fertility treatments. This obviously puts her in a tough spot.
Meanwhile, Mark makes it clear to Callie and Arizona that he takes his role as a father-to-be seriously, but that can't help but cause complications on the relationship front.
The sneak preview below shows just how tenuous their arrangement is. After an issue with the baby emerges, Mark and Arizona clash over the best course of treatment ...
Think the baby will be alright? Can Calzona's relationship survive Mark's unusual role?
Follow the jump for two more clips from "Not Responsible," both featuring Meredith. When Alex takes a look at her eyes, he can't pinpoint the source of her vision impairment, but the fact that she's having trouble seeing certainly isn't lost on her longtime colleague: