Subperiosteal abscess of the orbit.

Seven cases of subperiosteal abscess (SPA) of the orbit are reported. Anatomic relationships shared by the orbits, paranasal sinuses, and facial venous system explain the rapid development of SPA after periorbital infection. Computed tomography and echography allow distinction between SPA and other stages of orbital inflammation that are often indiscriminately grouped under the rubric of orbital cellulitis. These techniques suggest that elevated orbital pressure is the primary, and potentially reversible, mechanism of visual impairment produced by SPA. Difficulty in accurately determining the responsible pathogens, relative isolation of the subperiosteal space with regard to antibiotic penetration, and risk of precipitous visual loss require prompt surgical drainage in most cases.