Did you know that you can get rust on your cornea? I didn’t until some showed up on the cornea of my seven year old son (fyi: the cornea is the clear surface layer covering the iris and pupil). It seems he must have gotten something metallic in his eye and some remaining residue rusted. We luckily noticed it early on because it can cause permanent eye damage. Fortunately, an eye surgeon was able to buff it off with a Dremel-like device at the eye clinic, thus averting eye surgery.
Eye rust?
Bill Sjostrom, Eye rust?, Truth on the Market (June 09, 2006), https://truthonthemarket.com/2006/06/09/eye-rust/