I find contacts to be the most important part of my cycling gear.

But then I'm so deeply myopic (nearsighted) that when I wear my glasses instead of my contacts I can trip walking out of an escalator and have to turn my head down to eat because I can't see what's in my plate in the small gap between the bottom of my glasses and my cheeks.

Still, having the capacity to easily change the shade of my sunglasses (from yellow to brown to pink) is really nice.