How can people become blind even if their eyes are in perfect condition? This can happen if there is damage to the part of the brain that controls sight. Inside, You'll Find: How glasses and contact lenses work Diagrams, a time line, photos-and some tricky tricks for your eyes Surprising, True facts that will shock and amaze youHow can people become blind even if their eyes are in perfect condition? This can happen if there is damage to the part of the brain that controls sight. Inside, You'll Find: How glasses and contact lenses work Diagrams, a time line, photos-and some tricky tricks for your eyes Surprising, True facts that will shock and amaze you