If you mean how does eye pain relate to treatment response.....it doesn't.
But one of the side effects of treatment can be retinal bleeding which is a very serious problem. If you're on treatment, notify your physician immediately if you experience vision changes like: Blurry vision, black spots, floaters, blind spots, tunnel vision or eye pain.
Regarding vision sx's during tx, blurry vision is common. "Cotton Wool Spots", are not and only affects a small percentile. Before starting tx, some doctors recommend an eye exam. Retinopathy is something that you don't want to have a problem with, so if something very strange starts happening to your vision. Talk to your doctor asap.
God Bless