Silent sinus syndrome is a spontaneous, asymptomatic collapse of an air sinus (usually the maxillary sinus and orbital floor) associated with negative sinus pressures. It can cause painless facial asymmetry, diplopia and enophthalmos. Diagnosis is suspected based on symptoms, and can be confirmed using a CT scan. Treatment is surgical involving making an outlet for mucous drainage from the obstructed sinus, and, in some cases, paired with reconstruction of the orbital floor. It is slightly more common in middle age.