I am wondering if anybody else has experienced that they can´t read properly, it gets blurred, like you should get your eyesight checked out?

I have had it now for a while. When I am not tneced or stressed I can read books, websites etc really good. then suddenly it gets blurry and the sentences in a text gets blurred into each other. I have been thinking it´s my eyesight but on the other hand it could be related to that every time this is happening I am reading something importent. Like here at the AS or a book for my studies. Strange I think! I will get my sight checked up in the autumn.