Cellulitis is a common bacterial infection of the skin and underlying soft tissues. When this infection affects the area surrounding the eye, it is termed preseptal cellulitis, also known as periorbital cellulitis. This condition is an inflammation of the eyelid and the skin around the eye. While often alarming in appearance, it is typically less severe than other infections in this delicate area, but understanding its treatment is important for preventing complications.
Defining Preseptal Cellulitis
Preseptal cellulitis is a bacterial infection localized to the superficial tissues of the eyelid and the skin immediately surrounding the eye. The defining anatomical feature is its location anterior to the orbital septum. The orbital septum is a thin, fibrous layer extending from the bony rim of the eye socket into the eyelids, acting as a natural barrier between superficial tissues and deeper orbital structures. Because the infection remains in front of this septum, it involves the outer eyelid and surrounding soft tissue but does not extend into the eye socket itself. This anatomical confinement makes preseptal cellulitis relatively benign compared to infections that breach this protective layer.
Common Causes and Risk Factors
The bacteria responsible for preseptal cellulitis typically enter the body through a break in the skin near the eye. Common entry points include minor trauma, such as a laceration, or an insect bite. Infections in nearby structures, such as a stye (hordeolum), a blocked tear duct (dacryocystitis), or an inflamed cyst (chalazion), can also spread to the periorbital tissues. The infection may also spread from an upper respiratory infection or acute sinusitis, particularly in children.
The most frequently identified bacterial culprits are organisms normally found on the skin, such as Staphylococcus aureus or Streptococcus species. In cases linked to a sinus infection, bacteria like Streptococcus pneumoniae or Haemophilus influenzae are often involved. Young children, especially those under five years old, are particularly susceptible.
Recognizing the Symptoms
The clinical presentation of preseptal cellulitis is characterized by distinct, acute signs. Patients typically experience localized redness (erythema) of the eyelid and surrounding skin. This area will be noticeably swollen and feel warm or tender to the touch. The swelling can sometimes be severe enough to cause mechanical ptosis, making it difficult to open the eye. A mild fever may accompany these localized symptoms, especially in children. The eye itself is not directly affected by the infection.
The hallmark of uncomplicated preseptal cellulitis is the absence of more severe symptoms: vision must remain normal, there should be no pain with eye movement, and the eye globe should not bulge forward (proptosis). These negative findings are vital for distinguishing this less severe infection.
Preseptal vs. Orbital Cellulitis: Understanding the Distinction
The distinction between preseptal and orbital cellulitis (also called post-septal cellulitis) is important because it dictates the urgency and type of treatment. While both involve infection around the eye, orbital cellulitis is a much more serious infection that has penetrated the orbital septum and spread into the soft tissues within the eye socket. This deeper infection poses a threat to vision and, in rare cases, life.
Orbital cellulitis presents with severe signs absent in preseptal cellulitis. The most immediate sign is proptosis, or the bulging forward of the eyeball, caused by swelling and inflammation behind the globe. Patients will also experience pain when moving their eyes, and eye movements may be restricted or impaired (ophthalmoplegia). A decrease in visual acuity and double vision are additional indicators that the infection has progressed past the septum. Because the infection is deeper and closer to the optic nerve and the brain, orbital cellulitis carries the risk of complications like vision loss, orbital abscess, meningitis, or cavernous sinus thrombosis. Any suspicion of orbital involvement requires immediate medical attention and is usually treated with intravenous antibiotics in a hospital setting.
Diagnosis and Standard Treatment Protocols
The diagnosis of preseptal cellulitis is primarily clinical, based on a physical examination and the patient’s history. A healthcare provider inspects the eye for characteristic redness and swelling, while thoroughly checking for the absence of orbital signs like proptosis, pain with eye movement, or vision changes. The ability to move the eye normally and preserved visual acuity are often sufficient to confirm the preseptal nature of the infection.
In some cases, especially if swelling is severe or orbital cellulitis cannot be ruled out, imaging studies such as a computed tomography (CT) scan of the orbits and sinuses may be necessary. This scan helps visualize the soft tissues and confirm the infection is limited to the area in front of the orbital septum. Blood tests are generally not needed for straightforward cases but may be used in younger children or patients with systemic symptoms.
The standard treatment for uncomplicated preseptal cellulitis is prompt initiation of oral broad-spectrum antibiotics. The chosen medication typically targets the most common causative bacteria, Staphylococcus and Streptococcus species. An antibiotic like amoxicillin with clavulanate is a common choice, though the specific regimen may be adjusted based on local antibiotic resistance patterns.
Treatment usually lasts seven to ten days, and patients must be monitored closely to ensure the infection is resolving. Follow-up evaluation is important for children, who have a higher risk of the infection progressing. If symptoms worsen or fail to improve after 24 to 48 hours of treatment, immediate re-evaluation is necessary to rule out progression to orbital cellulitis.