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
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.