The biggest draw to The Big Bang Theory was its cast of characters. Originally comprised of four members: Sheldon (Jim Parsons), Penny (Kaley Cuoco), Leonard (Johnny Galecki), Howard (Simon Helberg), and Raj (Kunal Nayyar).
Apart from the personality and the traits that identify them, each role of the characters in The Big Bang Theory had a characteristic appearance. For Leonard Hofstadter (Johnny Galecki) that’s his hoodie and his dark-rimmed glasses.
Leonard wore glasses as a necessity because he had poor vision. This was the focal point of some episodes of The Big Bang Theory, including one in which his ex-girlfriend Priya (Aarti Mann) forced him to try on contact lenses.
Apparently though, the glasses he sported in the series were nothing more than display props as they had no lenses, but even with that, one would wonder why they had to go so far when he could have worn a pair without magnification.
Johnny Galecki explained that due to his height difference with Jim Parsons, he often had to look up when talking to him. And because of how the set was built this would cause the lenses to pick up the light and create a glare, which didn’t look good on camera.
That Johnyy Galecki wanted Leonard to wear glasses was a good decision. When The Big Bang Theory began, the four boys had their trademark elements in the series.
Howard wore dicks, Sheldon wore multi-layered clothing, Raj wore vests, while he wore glasses. The mere fact that Leonard was sporting a hoodie seemed not to be flashy enough to make an impression.
Now, the character Leonard Hofstadter (Johnny Galecki) from The Big Bang Theory is mostly synonymous with his glasses, as the tied merchandise uses him as a reference.