Peri-orbital and orbital cellulitis

Peri-orbital cellulitis is an infectious process occurring in the eyelid tissues superficial to (anterior to or above) the orbital septum. It is usually due to superficial tissue injury (e.g., insect bite or chalazion).

Orbital cellulitis is an infectious process affecting the muscles and fat within the orbit, posterior or deep to the orbital septum, not involving the globe. It is usually due to underlying bacterial sinusitis.

Peri-orbital cellulitis is of concern in children because it may be secondary to occult underlying bacterial sinusitis or, rarely, due to bacteraemic spread from a primary infection (e.g., pneumonia), and may rapidly progress to orbital cellulitis in children.

Complications include sub-periosteal abscess, cavernous sinus thrombosis, intracranial abscess, and subsequent loss of vision and/or death.

Peri-orbital (also known as pre-septal) cellulitis is inflammation and infection of the superficial eyelid, usually from a superficial source. The inflammation remains confined to the soft tissue layers superficial to the orbital septum and ocular function remains intact.

Orbital cellulitis is an infection within the orbital soft tissues with associated ocular dysfunction and is usually due to underlying bacterial sinusitis. Orbital cellulitis is a far more serious condition and warrants hospital admission. It has much higher morbidity than peri-orbital cellulitis, and warrants urgent imaging and surgical evaluation by oculoplastic as well as a head-and-neck consultant.