Each eyeball sits inside a boney cavity which protects the eye from injury. This cavity is called the orbit. The walls of the orbit are usually constructed of relatively thin bone which is capable of being fractured causing the wall to collapse ("blows out') into the underlying nasal sinus.This often happens after the eye and orbit are struck by a large solid object such as a fist or a baseball. When the wall of the orbit blows out contents of the orbit can enter the sinus sometimes causing double vision, restrictions in eyeball movement or rarely the whole eyeball disappears into the sinus. Often the patient will notice bleeding from their nose because the blood is coming from the fracured sinus wall. Sometimes infection can developed around the eyeball following a blowout fracture, contaminated from the bacteria in the sinus. Any suspected blowout fracture needs to examined and followed by your eye doctor. Occasionally, a blowout fracture needs surgery to repair the absent boney wall of the orbit but commonly it will repair itself.