Your character has been seriously hit in one or both of your eyes. This affects your Perception.”— In-game description
Attacks to the eye have a added Critical Chance which often requires the luck roll that if failed, blinds. Blindness lowers your accuracy, however the target for eyes is not in Fallout 3 or Fallout: New Vegas. Blindness affects your perception and most of the time the critical effect is death. The eyes are the hardest limb to hit, though.