Well, just as a benchmark, on a recent trip to Europe...well, a little backstory here - during the summer, I made a pair of spiked brass knuckles (basically a band of tape with nails sticking out of it - and don't flip out, I didn't plan to use it. I make things like that just to pass the time), and brought it over a friend's house in my backpack. Within that same backpack was also a metal wood-punching thing - basically a long metal spike. And these were both in my outer backpack pocket. Well, later that summer, I brought that same backpack along on my Europe trip as carry-on luggage. I emptied out the inner pockets, but forgot about the outer pockets. Well, I went through two checkpoints on the way there, and two checkpoints on the way back, and nothing was discovered. You can only imagine my face when I got back home from JFK and found spiked knuckles and a steel spike in my outer pocket. Still, it makes for a good story about National Security. And yes, this was after 2001.
Another time, my friend walked through two security checkpoints with a fruit knife on the OUTSIDE of her backpack - that's as in, on a little strap on the outside of the pack. As in, it was viewable to the naked eye at a glance. And this was a sharp knife - I cut myself deeply with it about 2 times during the trip - and again, it was carry-on. And like before, we nearly **** our pants when we realized what we had done.
If they can't catch steel spikes, spiked knuckles, and knives in plain sight, then they certainly can't catch bottles of eye drops in your pocket.