I hope yournamehere doesn't mind me stepping in here, but he or she seems to have stepped out.

I think the question is, when someone finds out that their friend wears contact lenses, they may be tempted to ask "Why did you lie to me?" Yournamehere seems to want to know if not mentioning your contacts is a lie or a deception. What do you think?

Me, personally, if I meet someone and have a friendship with them for a number of days or weeks and then find out they're wearing contacts, if they never mentioned their eyes, it's not a deception. I made the incorrect assumption that the person does not wear contacts.
If, however, I say "Wow, your eyes are such a bright green," that gives the person a chance to say "Thanks, they're emerald contact lenses." If the person does not mention the contacts at that point, it's deception. It's obviously fraud if someone asks them directly if they're wearing contacts and they say they're not.