Good polycarb is virtually unbreakable, and will sustain the impact of a ball or finger. Therefore, a frame made out of polycarbon is the the best choice. Shields are becoming more popular for this sport, however, do not offer the best protection. The frame must cover the entire eye socket, not only the eyeball itself. Look for a frame that sits closely to the face, as a finger can easily make its way through any gap.
Shields can easily become dislodged so a finger can penetrate underneath.
Be careful if choosing this option. Padding will absorb some of the shock to lessen the overall impact, and to assure the frame itself does not cause damage to the facial structures. You want something that will be secured tight to the head so that it won't fall off. A frame with temples will not hold tight enough, and a jab from a finger could lift the frame off, and make its way to the eye. An anti-reflective coating can also be placed on the lens to absorb additional glare off the indoor lighting.