I was hit directly in the eye once while backyard boxing (yeah yeah....tsk tsk I know). It knocked me on my ass and I couldn't see well in that eye for about a minute. Vision quickly recovered. I had a bad headache the next day, and a black eyelid (not eye, eyeLID....it was the most f'd up thing I've ever seen) for about a week and half. No problems whatsoever besides that.