Differentiating Preseptal and Orbital Cellulitis
Preseptal cellulitis, also called "periorbital cellulitis," is an infection of the soft tissues of the eyelid anterior to the orbital septum, a layer of fibrous tissue extending from the periosteum of the skull at the margins of the orbit to the anterior surface of the tarsal plates in the eyelids.[1] This fibrous membrane, which functions as a barrier to the spread of infection from the eyelid posteriorly into the orbit, defines the anatomical distinction between preseptal and orbital cellulitis.[6]
In contrast, orbital cellulitis is an infection of the orbital tissues, such as fat and extraocular muscles, posterior to the orbital septum. Whereas preseptal cellulitis is typically mild and rarely leads to complications, orbital cellulitis is a much more serious condition that can lead to devastating complications, such as loss of vision and even death.[7] Given that both conditions can present with similar clinical manifestations, it is important to distinguish between them, given their very different complications, treatments, and outcomes.
Both preseptal and orbital cellulitis are more common in children than in adults.[8] Preseptal cellulitis is much more common than orbital cellulitis. One retrospective case series of pediatric patients admitted to the hospital for either form of cellulitis found that 94% of cases were diagnosed as preseptal cellulitis.[9] Several sources of infection have been found, including, but not limited to, upper respiratory infection, sinusitis, acute dacryocystitis, local trauma, animal or insect bites, and foreign bodies.[6,9,10] One study reviewing inpatient preseptal cellulitis in a tertiary care facility found that dacryocystitis followed by upper respiratory infection and sinusitis were the most common predisposing factors.[10] In orbital cellulitis, the paranasal sinuses have been found to be the main source of infection.[9] It is uncommon for preseptal cellulitis to progress to orbital cellulitis, probably owing to the presence of the orbital septum.[1]
The bacterial etiology responsible for preseptal cellulitis is variable and reflects the pathogenesis of the condition, although it is unknown in most cases. In preseptal cellulitis caused by an external source, Staphylococcus aureus, Streptococcuspyogenes, and other anaerobes are the most common bacterial agents.[1,10] There have also been reported cases of preseptal cellulitis resulting from primary bacteremia due to Streptococcus pneumoniae.[1] Although Haemophilus influenzae used to be a very common cause, its incidence has sharply decreased after the advent of routine immunization in children.[9,11]
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Cite this: The Baby With a Swollen Eyelid - Medscape - Nov 19, 2018.
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