A good face shield not only protects your eyes but your face. I had this difference proven to me one day not long after I started turning. A bowl that I was working on exploded off the lathe and hit me squarely in the face with enough force to push me back. Had I not been wearing a full shield I would have had sever damage to my face not just a sudden wake up. Safety can never be over emphasized in wood turning. You are using razor sharp tools and spinning a piece of wood at hundreds or even thousands of revolutions per minute. Any unseen defect in the wood or turning at too high a speed could cause things to fly apart and that can cause serious injury or even death. We have lost members of the AAW family from just such an accident. Sometimes even those who have been turning a long time can get careless and bad things can happen in a split second.
There are several types of face shields available, I prefer the bubble type as I wear glasses and it gives you a little more room and a neck deflector to keep chips out of your shirt. Just make sure it has an impact resistant shield.