Before being depressed and being a bipolar, I used to look into everyone's eyes without bothering about anything..
But nowadays all I do in a crowd is just to look down and keep my hands tied. I asked some people about it and they were like this maybe because you are not feeling comfortable or just being scared of what would people judge you through their eyes.
But whenever I tell to myself that I don't care about what people might judge me about, looking through people's eyes got a little bit easier.
Hope it helps