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KembaraXtra -Medicine- Emergency and Acute Medicine – Periorbital and Orbital Cellulitis
Periorbital (preseptal) cellulitis and orbital cellulitis are infections involving the tissues around the eye, distinguished by their anatomic relationship to the orbital septum. The orbital septum is a connective tissue extension of the orbital periosteum that separates superficial eyelid structures from the deeper orbital contents. Periorbital cellulitis is confined to tissues anterior to this septum, whereas orbital cellulitis involves structures deep to it. This distinction is critical because orbital cellulitis is a true medical emergency with risk of permanent vision loss and life-threatening complications.
Periorbital cellulitis most commonly occurs as a complication of upper respiratory tract infection or sinusitis, where inflammatory edema leads to vascular and lymphatic congestion. It may also arise from local eyelid infections such as blepharitis, hordeolum, or dacryocystitis, or from surrounding skin disruptions including insect bites, minor trauma, impetigo, or dermatologic conditions. The septum typically acts as a barrier to deeper spread, although it may be incomplete.
Orbital cellulitis usually results from extension of infection from adjacent structures, most commonly ethmoid sinusitis penetrating the thin lamina papyracea. Other causes include dental abscess, retained orbital foreign body, puncture wounds, orbital fractures, postoperative infections, and hematogenous spread through valveless orbital veins. Rarely, it results from direct progression of periorbital cellulitis. Common pathogens include Streptococcus pneumoniae, Streptococcus viridans, Streptococcus pyogenes, Streptococcus anginosus, and Staphylococcus aureus. Anaerobes, Bacteroides species, and gram-negative organisms may also be involved.
All forms of orbital cellulitis carry significant morbidity and mortality risk. Complications include permanent visual loss, subperiosteal abscess, cavernous sinus thrombosis, and central nervous system infections. Fungal orbital cellulitis, particularly cerebrorhino-orbital phycomycosis (CROP), is rare but highly lethal, especially in immunocompromised patients and those with diabetic ketoacidosis. It often begins in the paranasal sinuses and invades blood vessels, causing thrombosis and tissue necrosis. Bloody nasal discharge and necrosis of the palate or nasal mucosa may be present.
In children, routine Hib and pneumococcal vaccinations have reduced incidence, but infection still occurs. Periorbital cellulitis is approximately five times more common and usually affects children younger than five years, whereas orbital cellulitis is more common in children older than five.
Both conditions present with unilateral red, swollen eyelids, and swelling may be severe in either. The key differences lie in systemic toxicity and ocular involvement. Orbital cellulitis is often preceded by sinusitis (60–90% of cases), dental infection, trauma, or recent surgery. Patients may report eye pain, visual changes, decreased color vision, diplopia, restricted or painful extraocular movements, and headache. Fever above 39°C and a toxic appearance are common. On examination, findings may include proptosis, conjunctival injection, chemosis, afferent pupillary defect, decreased visual acuity, ophthalmoplegia, and signs of meningismus.
Periorbital cellulitis typically follows local skin injury or superficial infection and presents more subacutely with low-grade fever and minimal systemic symptoms. Visual acuity and extraocular movements remain normal, and there are no signs of deep orbital involvement.
A complete eye examination is essential in all cases. This includes assessment of visual acuity, extraocular movements, pupillary response, fundoscopic examination, intraocular pressure measurement, and a thorough neurologic exam.
Laboratory studies are supportive but not diagnostic. A white blood cell count below 15,000 is more typical of periorbital cellulitis, whereas higher counts may suggest orbital involvement. Blood cultures and cultures of purulent material may be obtained, particularly if bacteremia is suspected. When gonorrhea is considered, appropriate culture media should be used.
Contrast-enhanced CT of the orbits is indicated when there are central nervous system signs, visual disturbances, proptosis, painful or restricted extraocular movements, ophthalmoplegia, bilateral edema, lack of improvement within 24 hours, or clinical deterioration. CT helps define the extent of infection, detect sinusitis, orbital emphysema, subperiosteal abscess, foreign bodies, and cavernous sinus thrombosis. Lumbar puncture may be necessary in toxic patients with meningismus to exclude CNS involvement.
Treatment depends on severity and depth of infection. Periorbital cellulitis in stable patients typically responds to oral antibiotics such as amoxicillin-clavulanate, cephalexin, clindamycin, or dicloxacillin. Parenteral antibiotics are indicated for toxic appearance, suspected bacteremia, or inability to tolerate oral therapy. Close follow-up within 24–48 hours is essential.
Orbital cellulitis requires hospital admission and immediate intravenous antibiotics. Early ophthalmology consultation is mandatory, and ENT consultation should be considered when sinusitis is the source. Empiric therapy commonly includes IV ceftriaxone or other broad-spectrum coverage, with vancomycin added if MRSA is suspected. Metronidazole may be included when anaerobic infection is likely. Surgical intervention may be required for abscess drainage, sinus decompression, or optic nerve decompression. In suspected fungal infection, high-dose IV amphotericin B and urgent surgical debridement are required.
Patients with periorbital cellulitis may be discharged if they have no systemic toxicity, no orbital findings, can tolerate oral antibiotics, and have reliable follow-up. Admission is required for orbital cellulitis, systemic toxicity, visual impairment, inability to arrange follow-up, progression on oral therapy, or high-risk conditions.
Any patient presenting with a red, swollen eye must be carefully evaluated for orbital cellulitis. A detailed history should include recent sinusitis, trauma, dental infection, surgery, immunocompromised state, or recent diabetic ketoacidosis. Clinicians must carefully assess for systemic toxicity, visual changes, pain with eye movement, and neurologic symptoms to avoid missing this potentially vision- and life-threatening condition.
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