What will cause blurry spots in my vision?

Many things. If you were younger (20s-30s), i would consider migraine headaches. Depending on your general health/medications taken, diabetes or cataracts could be something to talk to your eye doctor about. It would be important to know the frequency, duration, and circumstances regarding your blurry spots, because those details can make all of the difference in the world. I think it's time to see the eye dr.
So many possible. So many possible reasons...May be as simple as dryness, but could be from floaters due to a vitreous bleed. You need to see an eye doctor, especially if this is a new symptom.