How do you differentiate between orbital cellulitis and a stye (hordeolum)?

Differentiating Orbital Cellulitis from Stye (Hordeolum)

A stye is a localized, superficial infection of the eyelid margin involving a hair follicle or gland, presenting as a tender, erythematous nodule without systemic symptoms or vision changes, whereas orbital cellulitis is a sight- and life-threatening infection posterior to the orbital septum characterized by proptosis, painful/limited extraocular movements, and decreased visual acuity requiring emergent imaging and hospitalization. 1, 2

Clinical Features That Distinguish These Conditions

Stye (Hordeolum) Presentation

• Localized eyelid involvement only: A discrete, tender, red bump at the eyelid margin (external hordeolum) or inner eyelid surface (internal hordeolum)
• No orbital signs: Normal extraocular movements, no proptosis, no vision changes, no pain with eye movement
• Minimal systemic symptoms: Patient appears well, afebrile, no constitutional symptoms
• Self-limited course: Typically resolves spontaneously or with warm compresses within days to weeks

Orbital Cellulitis Presentation

• Proptosis (forward displacement of the globe): A hallmark finding that indicates postseptal involvement 3, 1
• Impaired or painful extraocular movements: Limitation of eye movement or pain with attempted movement distinguishes orbital from preseptal cellulitis 4, 5
• Decreased visual acuity: Vision changes indicate orbital involvement and potential optic nerve compromise 4, 1
• Ophthalmoplegia: Complete or partial paralysis of eye movements in severe cases 4
• Systemic toxicity: Fever, malaise, tachycardia, and leukocytosis are common 5, 2
• Associated sinusitis: The vast majority of orbital cellulitis cases originate from paranasal sinus infection, particularly ethmoid sinusitis 6, 2

Critical Examination Findings

Key Physical Examination Elements

• Visual acuity testing: Any decrease suggests orbital involvement requiring immediate imaging 4, 5
• Extraocular movement assessment: Pain or limitation with eye movement indicates postseptal infection 3, 4
• Proptosis evaluation: Compare eye position between affected and unaffected sides; proptosis is absent in stye but present in orbital cellulitis 3, 1
• Conjunctival examination: Chemosis (conjunctival edema) and injection suggest orbital cellulitis 5, 1
• Eyelid assessment: A stye presents as a discrete nodule, while orbital cellulitis causes diffuse periorbital edema extending beyond the eyelid 5

Clinical Pitfalls to Avoid

• Do not rely on clinical examination alone when orbital cellulitis is suspected, as clinical findings may not accurately differentiate preseptal from postseptal infection or identify complications 3
• Age >3 years, gross periorbital edema, high neutrophil count, absence of infectious conjunctivitis, and previous antibiotic therapy are risk factors for postseptal (orbital) involvement 3
• Inability to adequately examine the eye due to severe swelling mandates imaging to exclude orbital involvement 4

Imaging Requirements

When Imaging Is Indicated

• CT orbits with IV contrast is the most useful imaging modality for suspected orbital cellulitis, differentiating preseptal from postseptal cellulitis and identifying abscess formation 3, 4
• Imaging is mandatory when clinical features suggest orbital involvement, when the eye cannot be adequately examined due to swelling, or when there is failure to improve with antibiotics within 24-48 hours 4
• No imaging is needed for typical stye: The diagnosis is clinical and imaging adds no value

Imaging Findings

• Orbital cellulitis: Inflammation posterior to the orbital septum, possible subperiosteal or orbital abscess, underlying sinusitis, and potential complications including superior ophthalmic vein thrombosis or cavernous sinus thrombosis 3, 4
• Stye: No imaging performed; if inadvertently imaged, would show only superficial eyelid soft tissue changes

Management Implications

Stye Management

• Warm compresses applied 4-6 times daily for 10-15 minutes
• Topical antibiotic ointment may be used but is often unnecessary
• Incision and drainage for persistent or large lesions
• Outpatient management with no need for systemic antibiotics in uncomplicated cases

Orbital Cellulitis Management

• Immediate hospitalization with IV broad-spectrum antibiotics covering Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, Staphylococcus aureus, and anaerobes 6, 4, 1
• Ophthalmology consultation is mandatory 1
• Surgical intervention required in 49% of cases for abscess drainage or progression despite antibiotics 7
• Neurosurgery consultation if intracranial extension (cavernous sinus thrombosis, subdural empyema, meningitis) is identified 1
• Complications occur in 23% of patients and can include permanent vision loss or life-threatening intracranial spread 7, 2

Algorithmic Approach to Differentiation

1. Assess for vision-threatening features first: Check visual acuity, extraocular movements, and presence of proptosis 4, 1
2. If any orbital signs present (proptosis, limited/painful eye movements, vision changes): Obtain CT orbits with IV contrast emergently and initiate IV antibiotics 3, 4, 1
3. If only localized eyelid nodule with no orbital signs, normal vision, and normal eye movements: Diagnose as stye and manage with warm compresses
4. If extensive periorbital swelling prevents adequate eye examination: Obtain CT orbits with IV contrast to exclude orbital involvement 4
5. If preseptal cellulitis suspected (diffuse eyelid swelling without orbital signs): Consider outpatient oral antibiotics with mandatory 24-48 hour reassessment, or hospitalize if moderate-to-severe 4