I've been told that getting semen in your eyes is a very risky practice as far as HIV and other STDs. Not really something I'm into so I never verified.
Originally Posted by NadurraDrinker
This is very true. In the mouth, we have saliva that is strong enough to neutralize a lot of bad stuff, including HIV, but the eyes have no such protection. It also (mostly) bypasses the blood/brain barrier, so STD's that affect neural functions would be especially problematic. Heck, I bet you could even get a cold/flu passed that way.
Be aware of the risks, minimize them as best as you can, and then have your fun!