Ikari Gendou is a man reviled by most fans of Evangelion, it seems. He is cold and ruthless, forcing his son into unimaginably cruel situations. He seems to have more affection for Ayanami Rei than for his own flesh and blood. And even then, he used Rei to force Shinji into Unit 01 in that first episode.
But, there is a reason for that. Gendou, essentially, is in charge of saving humanity from destruction. At least, that is certainly how it seems. He believes that a Third Impact would destroy humanity. He needs to keep that in perspective, and must therefore be driving in his efforts to preserve the human race.
Now comes the glasses part. His pushing up his glasses symbolizes him focusing on that goal. He needs to adjust his vision constantly, to keep that in sight. It's a damned difficult job. No matter what, I can't really see him as someone who enjoys doing what he does. I think he probably has to force himself to do it.
Note, also, how he sometimes talks behind his hand while he does this, somewhat obscuring what it is he says. That, to me, represents how his cold, calculating ways seem to overshadow the fact that he is focusing on what is necessary. All of us see how harsh he is and then tend to forget that he has a reason, a very good reason, for doing things that way. And actions do speak louder than words.
So, do not be too quick to judge him. Although I may still not like him, I can certainly understand him. It is a tough burden to bear, and to do what needs to be done....
(Additional note: I find myself now adjusting my glasses using the, heh, "Gendou maneuver".)