|Yeah, he can see fine without 'em.|
Let's make one thing perfectly clear: There's nothing unmetal about having about poor vision. The last thing we in the heavy metal community want to do is discriminate against anyone... (with the exception of women, black people, and anyone that isn't metal)... So as long as that is understood, I'm not trying to offend anyone with this ruling. But rules are rules, and when you hit the stage, ready to melt some faces, it is common metal knowledge that the specs gotta come off of yours.
Sometimes you will catch studio logs or casual interviews where some of your favorite rock legends are sporting a classy pair of prescription eye wear. This may often come as a surprise to you, seeing how in every band shoot, music video and live performance you've ever seen them in, there are no glasses to be found. The explanation for why exactly rockers lose the corrective lenses before jumping in the spotlight remains a mystery, and it's not really a common violation like everything else I write about on TNM, but the fact remains: everybody else does it, and therefore so should you.
One possible theory is that the thrashing of your face to and fro from the non-stop headbanging, can easily cause your fragile frames to go flying. Glasses can get expensive, and if you're putting all your hard-earned cash into Gibson guitars and Krank amps, you're not going to have a red cent left for anything else. Another, less likely possibility, would be that taking off your glasses and shredding on your guitar while legally blind is a way to boast your epic musicianship. The fingers are flying and you don't have to see shit to make it happen, an impressive feat whether intentional or not.
The most likely reason however, is probably because heavy metal musicians are a bunch of self-conscious wussies, who have deep-rooted, irrational fears that their fans will think that they're dorky and not like them anymore if we see them in glasses. Me? Buy a metal album? FROM A NERD?! Fuck that. I only wear t-shirts of bands who have members who look cool and are cool. You can't be a metal legend and a four-eyes at the same time.