what is subperiosteal abscess
Orbital cellulitis may or may not progress to a significant subperiosteal abscess, orbital abscess, or cavernous sinus thrombosis. Subperiosteal abscesses are collections of purulent material between the orbital bony wall and periosteum. This entity may develop in 7-9% of patients initially with orbital cellulitis or from spread of an adjacent infection, as occurs when ethmoid sinusitis spreads to the medial orbital subperiosteal space.