What disability kept the fictional character George Bailey out of the army during WWII?

In the movie "It's A Wonderful Life" George Bailey receives a great gift. He finds out what the world would be like if he had never been born. This make him realize his existence is important and valuable to others and makes the world a better place.

George Bailey saves his little brother's life when the boy falls through the ice, and later stands up to the town druggist, who has accidentally poisoned a child's prescription. He is cuffed on the ear repeatedly, and because of these injuries loses the hearing in his left ear. This keeps him from serving in the Army during the WWII that sees his little brother win the Medal of Honor saving hundreds of lives when he shoots down a kamikaze plane.

He realizes he saved his brother and therefore all the soldiers on the ship, and saved the reputation of the druggist by keeping him from delivering the poisoned pills. His life of service for the Building and Loan company provides homes for poor people and makes him a town hero.

"It's a Wonderful Life" is considered one of the greatest films of all time. It was nominated for five Academy Awards, including Best Picture, and has been recognized by the American Film Institute as one of the 100 best American films ever made.