Preseptal cellulitis, also known as periorbital cellulitis, is an infection of the eyelid and periorbital soft tissues anterior to the orbital septum that usually occurs as a result of the spread of a nearby infection or trauma. Such predisposing factors include local eyelid infections (hordeola, dacryocystitis), sinusitis, upper respiratory tract infections, dental infections, otitis media, and eye trauma (eg, insect bites). It is more common in children under age 5 but can be seen in any age group. It presents clinically as acute eyelid erythema and edema. There may be associated fever, pain, nasal discharge, or conjunctivitis. The most common causative organisms are Staphylococcus and Streptococcus species. The rate of preseptal cellulitis attributable to Haemophilus influenzae type b has dropped considerably since introduction of a vaccine.

The main complication of preseptal cellulitis is potentially vision-threatening orbital cellulitis. Fortunately, the protective fibrous orbital septum prevents extension in many cases, but the clinician should be aware of and look for signs that indicate orbital involvement (refer to the Diagnostic Pearls section). Preseptal cellulitis should be treated promptly to prevent progression to orbital cellulitis.