Preseptal (periorbital) and orbital cellulitis

INTRODUCTION

Preseptal and orbital cellulitis occur most commonly in children. Orbital cellulitis occurs less commonly, but is more serious than preseptal cellulitis. However, these conditions may be difficult to distinguish clinically, and because orbital cellulitis may be sight- and life-threatening, diagnostic imaging (and at times surgical exploration) may be required to confirm the diagnosis.

Preseptal cellulitis, orbital cellulitis, orbital abscess, and subperiosteal abscess will be reviewed here. Orbital infections caused by the class of fungi, Zygomycetes, and Mycobacterium tuberculosis are discussed separately. (See "Zygomycosis (mucormycosis)" and "Tuberculosis and the eye".)

DEFINITIONS

Orbital cellulitis (postseptal cellulitis) is localized posterior to the orbital septum, (figure 1) and involves infection of the fat and muscle contained within the bony orbit. In contrast, the soft tissue infection, preseptal cellulitis (periorbital cellulitis), is localized anterior to the orbital septum (eg, outside the bony orbit).

ANATOMY

Sinusitis is the most common risk factor for orbital cellulitis in both pediatric and adult age groups [1]. In contrast, preseptal cellulitis is less commonly a complication of sinusitis. In a retrospective case series of 315 children admitted to the hospital with preseptal or orbital cellulitis, sinusitis was the underlying condition in all 18 cases of orbital cellulitis but only 44 of 297 cases (14.5 percent) of preseptal cellulitis [2].

The sinuses are major components of the walls of the orbit, and the lamina papyracea provides only a thin bony barrier between the sinuses (especially the ethmoid sinuses) and the orbital space (figure 2). The superior and inferior ophthalmic veins provide a valveless conduit between the sinuses, orbit, and face (figure 3).