SIGNS AND SYMPTOMS
Patients with preseptal cellulitis will present with an acutely painful, swollen eyelid. Because of the pronounced edema, the patient may not be able to open his or her eyes. However, there will be no disturbance in visual acuity or ocular motility, nor any signs of proptosis. There may be a concurrent history of sinus infection or congestion, penetrating trauma to the eyelid, or dental infection. In most cases, the patient will be systemically well and afebrile (not feverish).
The eyelid is separated into preseptal and postseptal areas by the orbital septum, which prevents the spread of infection to the orbit and central nervous system. Preseptal cellulitis is a bacterial infection of the eyelid anterior to the orbital septum. The routes of infection include direct inoculation from trauma, or spread of infection from the neighboring ethmoid sinus or teeth.
The most commonly encountered organisms include Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae. If a human or animal bite wound is the source, suspect anaerobic bacteria such as Peptostreptococcus and Bacteroides. If the infection spreads posterior to the orbital septum, it may result in a postseptal (or orbital) cellulitis, with associated vision loss, ocular motility restrictions and proptosis. Patients with orbital cellulitis are systemically ill and febrile.
To prevent the possibly disastrous spread of infection to the postseptal area, it is crucial to quickly suppress the infection. Oral therapy is necessary; topical antibiotics alone are insufficient. Amoxicillin 500mg PO TID is an excellent choice, although you may substitute nafacillin, oxacillin or cefazolin. If the cause is a bite wound, consider ampicillin or clindamycin. In cases of concurrent sinus infection, you may wish to consult an otolaryngologist to help you identify the involved organism.
Often, insect bites can mimic preseptal cellulitis, but these are rarely infectious. Instead, the patient will have a severe local allergic reaction. If the lid is not extremely painful upon palpation, it is usually an insect bite. A short course of oral antihistamines or steroids and cold compresses will often be sufficient. If you are in doubt as to the infectious nature of an insect bite, proceed with oral antibiotic therapy as well.
Lacrimal gland inflammation (dacryoadenitis) can also mimic preseptal cellulitis. Though rare, it usually occurs in adolescent viral infections such as mumps, influenza and measles.