Athletes competing in goalball have varying degrees of visual impairment; some are completely blind and have no light perception and others have low visual acuity. Athletes with a visual field of a maximum diameter of less than 40 degrees are also eligible to compete.
To ensure fair competition between teams, all players, including the goalkeeper, must wear eyeshades during the game.
Goalball was created exclusively for athletes with visual impairment. There are two teams of three players each on a court, which is marked with tactile lines and two goals at each side. The balls thrown towards the opponent's goal have bells inside and blocking with all the body is valid. Spectators must remain silent during the match, so that players can hear the ball moving.
Goalball was invented in 1946 as a rehabilitation sport for blind World War II veterans. Goalball made its debut at the Toronto 1976 Paralympic Games and at the Guadalajara 2011 Parapan American Games. All Para athletes wear eyeshade, so that people with varying degrees of vision can compete together.