Being dehydrated can indeed cause blurry vision.
When you're dehydrated and not taking in enough water or other hydrating fluids your eyes cannot produce enough tears to keep your eyes moist which can cause the blurry vision.
One of the symptoms of dehydration is blurry vision. Be sure to stay hydrated and drink plenty of water or other hydrating fluids even if you're not thirsty yet.
Headaches and double vision could also be a sign that your eyes are strained.