Exophthalmos due to nasal sinus disease is invariably unilateral. The most frequent cause of unilateral exophthalmos is suppurative sinusitis. The most common orbital complication of sinusitis is orbital cellulitis and abscess, which is usually the result of frontal or ethmoid sinusitis, involving the former in adults and the latter in children. It is also noteworthy that while suppurative nasal sinusitis is relatively common, yet the incidence of orbital phlegmon is infrequent and exophthalmos is rare.
To determine the incidence of suppurative sinusitis, orbital phlegmon and exophthalmos, the available reports of the Illinois Eye and Ear Infirmary for the last ten years were examined. Three hundred and fifty-seven cases of empyema of the accessory nasal sinuses which were involved as follows were recorded: frontal, 45 per cent.; maxillary, 28 per cent.; ethmoid, 24 per cent., and sphenoid, 3 per cent. Of 150 cases of orbital phlegmon, 146 were recorded as orbital