Fan Casting Four Eyes, Zero Soul in Sort by Tropes

So you have a guy who is cold, emotionless, or brutally practical, a little cruel or even a soulless monster. To quickly tip off the audience to his personality, give him glasses. The eyes are said to be windows of the soul, so hiding them behind glasses makes the character seem more removed. They mask the spitefulness on a villain's face and usually after the facade is taken off it is seen in their eyes (often going with Creepy Shadowed Undereyes of evil). Particularly effective if the glasses have Opaque Lenses and you can have the light reflect off them in scary ways.