The Big Bang Theory has amassed a seriously devoted, almost rabid, following. There are Tumblrs devoted to Sheldon Cooper's comic-inflected wardrobe, 'shippers writing novellas about Penny and Leonard, and the series even has its own conventions — which is super-meta, since the show riffs on Comic-Con and other events like it all the time. However, even the most die-hard fans might not know this one detail, which has been constant since the series' pilot episode: Leonard Hofstadter's glasses have no lenses. Actor Johnny Galecki, who plays Hofstadter, revealed all while promoting his new horror flick, Rings. "We rehearsed the first episode for about a week and a half, and when we started to shoot, they said, 'Well, you’re gonna take your glasses off, right?' I said, 'No, I want Leonard to wear glasses.' They said, 'Oh, we just thought you were wearing them as Johnny for rehearsal all week,'" Galecki told AOL's Build. But method acting isn't the only reason for the lens-free frames. Since he and his co-star, Jim Parsons, have quite a height difference (5-foot-5 Galecki often has to crane his neck to make eye contact with 6-foot-1 Parsons), Galecki adds that when he would look up to speak during the show's signature warp-speed back and forths, lenses would reflect the set lights. "I quickly popped out the lenses, and that's the movie magic behind that," he added. Now that you know, it'll be tough to watch an episode without taking notice of Hofstadter's quirky, glass-free specs. Will CBS use a similar trick for its purported BBT spin-off? You'll have to wait and see.