Preseptal and orbital cellulitis

Overview & Definition

Picture a four-year-old brought to the emergency department with a swollen, red eye. Yesterday it was a mildly puffy lid after a small scratch; today the whole lid is tense and erythematous, but the eye itself looks normal, the child can move it in every direction without pain, the vision is fine, and the child is playful and afebrile. This is the common, benign end of the spectrum — preseptal cellulitis — and it will settle with oral antibiotics and safety-net advice. Now picture a different four-year-old, brought in the same evening with a swollen, red eye that protrudes, cannot look to the side, hurts when it tries, and is accompanied by fever and a listless child. This is the dangerous end — orbital cellulitis — and it will not settle without a hospital, an intravenous line and a scan. Recognising which child is which, and acting fast on the second, is the whole skill. [1] [3]

Periorbital infection is divided by the orbital septum, a fibrous sheet continuous with the periosteum of the orbital rim that forms the anterior boundary of the orbit. Preseptal (periorbital) cellulitis is infection of the eyelid and periorbital soft tissues anterior to this septum; it is common, usually mild, and most often follows a local skin breach, conjunctivitis or trauma. Orbital (postseptal) cellulitis is infection posterior to the septum, involving the orbital fat, extraocular muscles and neurovascular structures; it is uncommon but sight- and life-threatening, and it most often spreads from adjacent paranasal sinusitis. [2] [4]

The clinician's task is layered. The first layer is triage — separating the well child with anterior lid swelling from the sick child whose infection has crossed the septum, using the orbital signs that examiners test every time. The second layer is investigation — deciding when contrast CT is needed and reading it for a subperiosteal or orbital collection. The third layer is treatment — oral antibiotics for uncomplicated preseptal disease, intravenous antibiotics for orbital disease, and a surgical decision for the abscess that will not resolve or that threatens vision. [5] [11]