I was wondering that myself about an hour ago, so I asked google. Google says that he had an operation on his right eye for glaucoma in 1999, since when he has been extra sensitive to light (hence the shades) and unsuitable for using contact lenses. He has special permission from FIFA to wear his goggles instead of contact lenses, and also special permission to use an eyewash which contains a substance which is normally on the banned list.