What Causes Blurred Vision While On Vesicare?

I ve been taking Vesicare for 2 years; 10mg 1x day for the first year, then dropped to 5 mg daily as I was troubled with blurred vision. That seemed to help for a while, but now my vision seems to be getting worse. Is this permanent or will there be some improvement if I stop taking Vesicare and/or switch to another medication for bladder control problems?