First please make sure the eye exam you have done is in recent days, if it shows the result is fine, I think your blurry vision may be a symptoms of dry eyes, Migraines or Cataracts . So it is urgent for you to have a careful eye examination to make a definite diagnosis of the cause of your blurry vision.
If you have checked your eyes recently and found no eye problems, then the blurry vision may be caused by eye strain or fatigue. That is to say, if your eyes work too long, such as staring at a computer screen, then you will have blurry vision intermittently. In this case, your eyes should have enough rest, then your blurry vision will disappear.