Not really a first aid item, but...
Repair kit for glasses wearers.
Tonight I lost a screw that holds the frame together, thereby letting the lens fall out! Tape WILL work, but makes you look like a Geek that should be wearing a pocket protector. Yeah yeah, I've been there.
By having this small kit in your FAK or IFAK, you will always have it readily available if you should need it. I'm going to add one to my kit.