Orbital and periorbital infections

Epidemiology & Risk Factors

• Preseptal (Periorbital) Cellulitis: Infection anterior to the orbital septum.
  • Risk factors: Local skin trauma, insect bites, dacryocystitis, chalazion, upper respiratory infection (URI).
• Orbital (Postseptal) Cellulitis: Infection posterior to the orbital septum.
  • Risk factors: Bacterial rhinosinusitis (most common cause, especially ethmoid sinusitis via thin lamina papyracea), dental infections, orbital trauma/surgery.
• Pathogens: Streptococcus pneumoniae, Staphylococcus aureus (including MRSA), Streptococcus anginosus group, non-typeable Haemophilus influenzae.

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Clinical Features

• Preseptal Cellulitis:
  • Unilateral eyelid erythema, edema, warmth, tenderness.
  • Normal extraocular movements (EOM) without pain.
  • No proptosis.
  • Normal visual acuity and normal pupillary light reflex.
• Orbital Cellulitis:
  • Eyelid edema, erythema, and systemic signs (fever, leukocytosis).
  • Pain with EOM and ophthalmoplegia (diplopia). c
  • Proptosis (exophthalmos).
  • Decreased visual acuity, sluggish pupil response, or afferent pupillary defect (APD) in severe disease.

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Diagnosis

• Initial/Screening: Clinical examination (assessment of EOM, proptosis, and visual acuity differentiates preseptal vs. orbital).
• Key Labs: CBC with differential (leukocytosis with left shift), blood cultures (if high fever or systemic toxicity).
• Imaging (Gold Standard for Orbital): CT scan of orbits & sinuses with IV contrast.
  • Indications for CT: High clinical suspicion for orbital involvement, inability to properly examine eye (severe edema), presence of proptosis/ophthalmoplegia, or no response to Abx in 24–48 hr.
  • Findings: Orbital fat stranding, extraocular muscle thickening, subperiosteal abscess (SPA), orbital abscess.

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Differential Diagnostics

• Preseptal Cellulitis: Differentiated from orbital cellulitis by absence of proptosis, absence of EOM pain/restriction, and normal vision.
• Cavernous Sinus Thrombosis: Differentiated by bilateral symptoms (rapid progression to contralateral eye), severe retro-orbital headache, papilledema, and cranial nerve palsies (CN III, IV, V1/V2, VI → ptosis, loss of corneal reflex).
• Thyroid Eye Disease (Graves): Bilateral proptosis, lid retraction/lag, non-infectious (afebrile), subacute/chronic, hyperthyroid lab findings (↑ free T4, ↓ TSH).
• Allergic Conjunctivitis / Blepharitis: Bilateral, intense pruritus, conjunctival injection, absence of severe eyelid pain or systemic symptoms.

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Management

• Preseptal Cellulitis:
  • Outpatient management with oral antibiotics covering S. aureus & Streptococcus spp.
  • First-line options: Clindamycin OR TMP-SMX plus (Amoxicillin-clavulanate OR Cefdinir).
• Orbital Cellulitis:
  • Inpatient emergency admission + immediate Ophthalmology & ENT consults.
  • First-line (Medical): Empiric IV broad-spectrum Abx (IV Vancomycin PLUS Ceftriaxone/Cefotaxime OR Ampicillin-sulbactam OR Piperacillin-tazobactam).
  • Second-line / Surgical intervention: Emergency surgical drainage (indicated for subperiosteal/orbital abscess, refractory to IV Abx after 24–48 hr, or progressive optic neuropathy/visual loss).

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Complications

• Subperiosteal abscess (most common surgical complication).
• Orbital abscess and orbital compartment syndrome.
• Optic neuropathy and permanent visual loss (due to ischemia or optic nerve compression).
• Intracranial extension: Cavernous sinus thrombosis, meningitis, epidural/subdural empyema, brain abscess.