Well, it is rarely to suffer blurred vision because of period. It is true that too much blood will loss during that time, however, it is normal and the basic physiological reaction for women. Blurred vision is an ocular symptom, which can be caused by many factors, such as eye infection, inflammation, or injury, floaters, retinal detachment, glaucoma and diabetes. So you can check your condition and think which cause fixes you. If you're experiencing blurred vision, you should go see your eye doctor as soon as possible. Reading glasses and contact lenses can help you reduce your condition. But if your conditions are very severe, you need to take surgery to heal it.
It is not normal. The blurred vision may be caused by the coming bacterium which is invisible. You need to take great notice of. You'd better drink more water recently. You could use the eye drops with anti-inflammation to get rid of the inner bacterium in the eyes and make the eyes feel comfortable. You could also use the warm compress to make your eyes feel comfortable.