Periorbital cellulitis is a common bacterial infection affecting the eyelid and the skin surrounding the eye. It causes inflammation and swelling in the tissues located just in front of the bony eye socket. Although typically manageable with antibiotics, the condition requires prompt medical attention due to its proximity to the eye and the potential for the infection to spread. This infection is more common in children, but it can affect adults as well.
Understanding Periorbital Cellulitis and the Crucial Distinction
Periorbital cellulitis is also known as preseptal cellulitis because the infection is confined to the soft tissues located anterior to the orbital septum. The orbital septum is a thin, fibrous membrane extending from the bony rim of the eye socket into the eyelids, acting as a protective barrier. This anatomical boundary makes the infection generally less severe than its counterpart.
The most important distinction is between periorbital and orbital (postseptal) cellulitis. Orbital cellulitis has crossed the orbital septum and involves deeper structures within the eye socket, such as the fat and muscles. This deeper infection is a medical emergency because it carries a significant risk of vision loss, intracranial complications, and death.
How to Recognize the Signs
The signs of periorbital cellulitis generally appear abruptly and are localized to the area around one eye. Observable symptoms include noticeable swelling, redness, and a feeling of warmth or tenderness in the upper and lower eyelid. Patients may also experience a fever or difficulty opening the affected eye due to the swelling.
Unlike the periorbital form, orbital cellulitis often presents with pain when moving the eye, decreased vision, or the eyeball bulging forward (proptosis). The presence of double vision or an inability to move the eye normally are strong indicators of a deeper, postseptal infection that requires immediate emergency care.
Sources of Infection and Vulnerability
Periorbital cellulitis is most frequently caused by common bacteria that enter the tissues through a break in the skin near the eye. These bacteria include Staphylococcus aureus and Streptococcus species, which are often found on the skin or in the nose. Streptococcus pneumoniae is another common culprit, especially when the infection develops without a clear entry point.
The entry point for the bacteria is often a preceding local injury, such as a scratch, a cut, an insect bite, or a localized skin infection like impetigo or a stye. The infection can also spread from nearby structures, most commonly from an upper respiratory tract infection or bacterial sinusitis due to the close proximity of the sinuses to the orbit.
Diagnosis and Treatment Protocols
Diagnosis of periorbital cellulitis begins with a thorough physical examination to assess the extent of inflammation and look for signs suggesting orbital involvement. The doctor will check for pain with eye movement, changes in vision, and any bulging of the eyeball to rule out the more severe infection. If there is uncertainty about the infection’s location, or if the patient is very young, imaging studies may be ordered.
A contrast-enhanced computed tomography (CT) scan is the primary tool used to differentiate between preseptal and postseptal infection, providing clear images of the orbital septum and deeper structures. Blood tests may also be performed to check for signs of a systemic infection, such as elevated inflammatory markers. This diagnostic clarity guides the urgency and method of treatment.
Treatment for uncomplicated periorbital cellulitis typically involves a course of oral antibiotics, often covering the common Staphylococcus and Streptococcus bacteria. A common regimen might include amoxicillin-clavulanate for a duration of seven to ten days. Patients with mild symptoms who are older than one year can often be managed safely as outpatients with close medical follow-up.
Hospitalization and intravenous (IV) antibiotics are required for infants under one year old, individuals with severe symptoms, or those who show any signs of orbital involvement. IV therapy, which may involve broad-spectrum antibiotics like ceftriaxone or clindamycin, is administered for 48 to 72 hours until clear clinical improvement is observed. Patients are then typically transitioned to an oral antibiotic regimen to complete the full course of treatment at home.