The victim, 57, was arguing with another man inside the 14th St.-Union Square subway station, when the assailant stabbed him in the right eye with a sharp object.

A crazed attacker stabbed a straphanger in the eye in a lower Manhattan subway station early Saturday morning — and police have enlisted the public’s help as they hunt for the violent brute. The 57-year-old male victim was inside the 14th Street-Union Square station at about 12:46 a.