headstand resulting in red eyes

Just wondering why this happens. I know Colin had talked about it before, but please remind me of why one gets red eyes. Of course after Sarah said headstand on a chair is good for anyone, except the obvious heart problems and glacoma, I offered it to a class on Monday. One of the girls started laughing when she was up in headstand. She was up for 10 seconds at most. When she came down, her eyes were red and her face felt swelled and puffy (looked kinda like that too). By the end of class she looked better and by the next day everything was normal (no broken blood vessels thank god.) So any ideas of what happened? I modified my class after that and we didn't do any forward bending, as I felt that would've been a bad idea. Does anyone agree? Any suggestions of what went on? This was our 8th or 9th class, so I thought we would've done enough downward dog, forward bends etc. for the body to be prepared for this. Thoughts?

Roberta

laughing increases blood flow to your face (cheeks get red). so does headstand. the combination of both REALLY increases blood flow to the face. she is lucky she didn't burst blood vessels.