How long til vision improves?

Hey Ladies....I have a ? for those of you that had vision problems from Mirena. Mine is hard to explain, I can see fine. It just seems like I can't stay focused on things(like my eyes want to wander). They feel fatigued alot of the time. I still have the brain fog somewhat, so not sure if that is the part of the problem. I haven't been to an eye Dr. I am hoping it improves on it's own. How long til you noticed significant improvement? I know for some of you it was instant, but for those that it took longer, how long was it? I am 4 months post. They are also dry alot. Any comments would be greatly appreciated.