Hi Bridget -
I just did a brief survey on Pubmed, the largest medical database. I could find very little on the relationship between quetiapine and eyesight. I am sure that, had there been a real connection, that there would have been hundreds of articles.
However, I found just one publication on the link between apiprazole (another atypical adjunct medication) and myopia (a patient went from 20/20 vision to blurred, myopic vision). But when he stopped it, he got promptly back to his perfect vision. So if there's something, it seems to be 100% reversible. A lowering of the dose could already be helpful.
The tentative upshot: there's no reason for fear of panic. You are right in going to the optician, he/she can determine what exactly has happened, in technical terms, and also see if something purely physical has changed (retina, ability to focus, whatever).
Hope this eases your mind a bit,
Cuthbert.