I've just discovered that the EN166F rating for safety specs only protects up to the velocity of 45 m/s or 150 fps, as I couldn't remember what mine were rated, I went upstairs and checked my safety glasses and discovered that they were indeed rated EN166F.
They are made by a company called "Strike Systems", who seem to be Europe based and have something to do with ASG, if not part of them. On the day I got them I shot them point blank with a good AEG that's firing around 340-360 fps (I think) and only a little scratch was left.
I've used them in each event I've been to and I'm sure they've been hit at least once. So my question is, am I safe to keep using them or should I buy some higher rated ones?
Although the specs means nothing to me, if you are in any doubt then you should invest in a higher quality eye pro - never take any chances with you sight buddy! 
You want 'B' rated ones at the very least to guarantee protection.
A Proud Member Of 'Team Spleen!' who play mainly at Gunman Airsoft, Tuddenham, Suffolk.
Just had a quick google and found this quote:
My Health and Safety Officer has said that I need to use Grade B eye protection, but I can’t find any safety spectacles that are to that requirement?
Grade B is tested by firing steel balls at the eye protector at 270mph (430kph). The European Standard does not allow for spectacles to be tested at this speed. This is because the spectacle just sits on the wearer’s nose all the impact energy has to be absorbed there and the wearer would receive excessive injuries. For Grade B protection you will need goggles or a faceshield. Generally speaking, if you are using hand tools spectacles will be needed and goggles and faceshields if you are using power tools.
Here's the website: http://www.jsp.co.uk/faqs.aspx?&id=19
So basically I'm looking at getting some goggles or a facemask? It appears this means that no safety glasses are actually protecting us, which is quite worrying. That said, the glasses are tested by firing an 0.86g (or thereabouts) 6mm steel ball bearing at 45 m/s. Am I right in thinking that this would have more kinetic energy than a 0.25g 6mm plastic bb, or am I completely wrong? Physics isn't my strong point. 
What, firing steel balls at 270mph? That would take your head off so I think eye protection would be your least concern! That advise seems a bit weird - the EN 166 B standard is 6mm 0.86g steel ball at 120m/s, which as Rob says is the one to go for (but I think the B standard only covers goggles, not glasses, which is I guess where the nose impact concern comes in).
Don't get too worked up about it - think of the tens of thousands of players who are using standard branded and marked eye protection without problems. I use British military spec glasses and have complete confidence in eye protection. Mind, I gone through a few pairs of specs over the years as the standards concern themselves with the lenses, not the frames. A BB in the wrong place can easily smash the frame (and has, hence replacements).
A point blank test to the lens with a known and powerful bb gun should satisfy yourself (but bear in mind your lens is compromised now!) and you are wise to check the glasses carry a safety rating, so that is good.
Reference: http://safetyspecs.co.uk/BS%20EN%20166.htm
My safety specs are the type that have an "integral frame" if that makes sense, so no worries of the frame breaking, the arms are on hinges attached directly to the lenses and there's quite a lot of thick plastic around the screw.
I haven't been able to find EN 166 B rated safety glasses, and I'm not too keen on the idea of goggles or a facemask.
Considering that I've only heard of eyes being shot out in cases where specs fell off, mesh was dislodged/caused a BB to fragment and cause injury, or a BB managed to somehow get behind the lens, I think I'll stick to the glasses I have now unless the quote I posted above is inaccurate and you can in fact get B rated specs.
Cheers for all of the advice guys, Moss.
