Preseptal cellulitis, also known as periorbital cellulitis, is a common bacterial infection affecting the skin and soft tissues of the eyelid and the area immediately surrounding the eye. This condition presents with acute inflammation and swelling but is generally limited to the most superficial layers of the tissue. While it requires prompt medical attention, this infection is typically considered less dangerous than its counterpart, orbital cellulitis, which involves deeper structures. The distinction between these two conditions is important because preseptal cellulitis responds well to outpatient antibiotic therapy, whereas the deeper infection often necessitates immediate hospitalization.
Anatomy, Causes, and Risk Factors
The anatomical structure that defines this condition is the orbital septum, a thin, fibrous membrane that extends from the bony rim of the eye socket into the eyelids. This septum acts like a natural curtain, physically separating the front part of the eyelid from the deeper structures of the eye socket, called the orbit. Preseptal cellulitis is characterized by an infection entirely anterior to this septum, meaning the bacteria have not penetrated this protective barrier to reach the sensitive fat, muscles, and nerves within the orbit.
The infection is typically caused by common bacteria, most frequently Staphylococcus aureus and various Streptococcus species, which are part of the normal skin flora. The bacteria usually gain entry through a break in the skin near the eye, often resulting from minor trauma, such as cuts, scrapes, or insect bites.
The infection can also spread contiguously from a local infection, such as a stye (hordeolum), a blocked oil gland (chalazion), or impetigo. In some cases, the infection may originate from an upper respiratory tract infection or sinusitis, spreading from the adjacent nasal passages.
Risk Factors
Certain factors increase an individual’s susceptibility to developing this condition.
- Recent eye surgery.
- An underlying compromised immune system.
- Lack of vaccination against certain bacteria like Haemophilus influenzae.
- Poorly managed local infections or chronic conditions like dacryocystitis (tear duct infection).
Identifying Symptoms and Differential Diagnosis
The presentation of preseptal cellulitis is marked by specific and observable signs localized to the area around the eye. The most noticeable symptom is significant, often unilateral, swelling and redness of the eyelid and the surrounding skin. The affected area will feel warm to the touch and tender, or painful, when pressure is applied. A low-grade fever may also be present, particularly in children.
The clinical presentation is characterized by what is absent, which is the most crucial information for distinguishing it from the more severe orbital cellulitis. A person with preseptal cellulitis will maintain normal visual acuity, meaning their vision is unaffected. Furthermore, there will be no pain when the eye is moved, and the patient will not experience double vision (diplopia). The eyeball itself will not bulge forward (proptosis), a sign that indicates the deeper orbital tissues are involved.
A medical evaluation is always necessary to confirm the diagnosis and perform the differential diagnosis. The primary task for healthcare professionals is to definitively rule out orbital cellulitis, which involves infection behind the orbital septum. While the clinical presentation is often enough to differentiate the two, imaging studies are frequently employed for absolute confirmation.
A computed tomography (CT) scan of the orbits is the standard diagnostic tool used to visualize the deeper structures and establish the precise location of the infection. The CT scan confirms preseptal cellulitis when it shows soft tissue swelling anterior to the septum, without any evidence of inflammation, abscess formation, or fat stranding within the orbit itself.
Treatment Protocol and Expected Recovery
The standard treatment for preseptal cellulitis is a course of oral antibiotics, which are highly effective because the infection is superficial and contained. The choice of antibiotic, such as amoxicillin-clavulanate or clindamycin, is selected to cover the most common bacterial culprits, including Staphylococcus and Streptococcus species. If a patient is systemically well and the infection is considered mild, treatment can usually be managed on an outpatient basis.
Hospitalization may be required for certain patient groups, such as young children, individuals with severely compromised immune systems, or those whose symptoms suggest a more severe infection. In these cases, or if the patient does not show improvement after 24 to 48 hours of oral treatment, intravenous (IV) antibiotics are administered to ensure rapid and complete resolution. Applying warm compresses to the affected area several times a day is often recommended to help alleviate discomfort and promote localized drainage.
Close monitoring and a follow-up appointment are essential to confirm that the infection is resolving as expected. Once the initial swelling and redness begin to subside, the patient may be transitioned from IV to oral antibiotics to complete the course. Clinical improvement is typically noticeable within 48 to 72 hours of starting antibiotic therapy, with most uncomplicated cases achieving full recovery within a seven to ten-day course. If the underlying cause, such as chronic sinusitis, is not addressed, there is a possibility of the infection recurring.