A “foreign body” means anything that doesn’t belong in the eye, like specks of dirt, a loose eyelash, etc. Nothing to do with nationality nor sensuality. Foreign bodies on the conjunctiva cause an itchy, gritty, uncomfortable sensation. There’s often tearing, but vision is normal except for tears getting in the way. True pain means the cornea is involved, or deeper parts of the eye, all of which are much more serious (see Keratitis).
Sometimes a foreign body can get stuck on the eyelid, and the irritation doesn’t go away. It’s easy to see on the lower lid, but harder inside the upper lid. It may be necessary to briefly flip the upper lid inside-out, & look carefully under good lighting. Treatment for foreign bodies is to remove them, obviously.
As an aside, if someone happened to get a weird sense of “something in my eye” while working in a metal shop, or any place people were cutting or hammering steel, it’s possible that a tiny piece of metal penetrated the eyeball, which rapidly sealed itself. The symptom may have completely disappeared, but the fact that it was felt in such a setting requires a referral to an Ophthalmologist, even if no treatment winds up necessary.
People can live & see just fine with tiny pieces of metal deep in their eyes. But if they ever get an MRI for any reason, the magnet will whip that tiny unnoticed piece of metal back & forth [yuck!]. MRI techs always ask about the possibility first; I’ve always wondered if that got thought out ahead of time, or if it took a couple of bad outcomes to raise the query.