I think you have some vision problems. Vision changes and problems such as blurred vision can be caused by many different reasons. Whether you have presbyopia? This is common in the elderly. Cataracts are one of the causes. Glaucoma can be another cause of blurred vision. Diabetic retinopathy can lead to bleeding into the retina, which is another common cause of blurred vision.
Macular degeneration can cause loss of central vision, blurred vision and distorted vision. Infections, inflammation, or injury can cause blurred vision too. TIA or Stroke, brain tumor or bleeding into eyes can also cause blurred vision. But I think your temporary blurred vision may caused by fatigue, overexposure to the outdoors. You can have some rest to solve your problem. If it doesn't work, you should see your eye doctor.
Temporary loss of vision can occur if the circulation to the eye is impaired for a period of time. The two main causes for this happening are: Narrowing of the main blood vessels to the eye (the carotid arteries) Bits of material that break off from inside the heart or along the lining of the carotid arteries and travel to the eye.These pieces can get lodged in the main blood vessel of the eye and block circulation. In a young person without risk factors for heart problems or atherosclerosis (hardening of the arteries), migraine is a possibility. I would suggest you do two things: Notify your primary care doctor, and have an eye examination by an ophthalmologist.