A coin thrown at a police officer at a football match had to be removed by a doctor after becoming lodged in his socket, police said.
The officer was injured, but not blinded, in the attack outside Villa Park after the club's victory over Cardiff on Tuesday.
West Midlands Police said a 14-year-old girl also suffered a facial injury after being hit by a bottle.
Both were hurt as away supporters were held back in the coach park.
The force said the officer was left with some bleeding around his eye, but the cornea remained intact. He is undergoing a course of antibiotics and returned to work within hours.
Inspector Nigel Sarling, from West Midlands Police, said: "It is completely unacceptable in society, let alone at a football game, to see such stupid and senseless acts.
"A teenage girl was left with a bloody nose and we don't underestimate how traumatic an experience this will have been.
"One of our officers could quite easily have been left blinded in one eye and we will be offering our full support after what was a highly distressing situation."
The fixture ended in a 1-0 win for Aston Villa.