He was in the hospital for several weeks and had a very real possibility of loosing site in his eye. Injuries like these may not be uncommon. There are a variety of eye injuries that have been associated with balloons. Popping balloons can also cause a contusion to the eye or the face. Balloons are frequently thought of as children's toys or decorations, but because of the potential for problems in vision, infection and so on, even minor injuries may very well require medical attention.
Balloons can also be an excellent avenue to pass on germs and disease.
Never put a balloon in or on your mouth after another person has done so. There is nothing like fresh saliva to transmit germs. Hang balloons high enough so children cannot reach them. Keep a close eye on children who may be holding balloons and make sure they know not to place the balloon in their mouths or near the face. If a balloon breaks, immediately collect the pieces and discard them.