neither does glass....once the initial pain and irritation goes away the eye will heal itself over glass.ceramic etc..... once it doesn't hurt...you think it's all good....well your wrong...the material still can move inside the eye......eventually causing more damage.

Rust is obviously worse .....so the pain doesn't go away.....it gets worse.

be careful with eyes...like I said.I had about 10 pieces in one eye when I had an accident years ago.....luckily I went to the eye doctor..