- An inflammatory, typically infectious condition affecting the eyelid(s)
- It is anatomically distinguished by its location, isolated to the tissues anterior to the orbital septum:
- Orbital septum is the connective tissue extension of the orbital periosteum that is reflected into the upper and lower eyelids
- Extension to the deep tissues is rare because the septum represents a nearly impenetrable barrier but it may be incomplete
- Most commonly presents as a complication of upper respiratory tract infection (URTI) and sinusitis:
- Swelling is caused by inflammatory edema from vascular and lymphatic congestion
- May occur as a complication of a localized inflammation/infection in the eyelid or adjacent structures:
- Blepharitis
- Hordeolum
- Dacryocystitis
- Surrounding skin disruptions:
- Insect bites
- Minor trauma
- Impetigo or other dermatologic disorders
- Inflammatory process in the structures deep to the orbital septum
- Typically occurs secondary to extension from an adjacent structure:
- Sinusitis:
- Most commonly ethmoiditis penetrating through the thin lamina papyracea
- Dental abscess
- Retained foreign body in the orbit
- Puncture wounds
- Orbital fracture
- Postoperative infection
- Hematogenous spread from a remote source due to valveless orbital veins
- Rare cause—direct extension of periorbital cellulitis
- Sinusitis:
- Streptococcus pneumoniae
- Staphylococcus aureus
- Streptococcus pyogenes
- Moraxella catarrhalis
- Haemophilus influenzae
- Gonococcus – rare
- Consider nonbacterial cause
- Currently streptococcal and staphylococcal infections are the most common causes:
- S. pneumoniae, Streptococcus viridans, S. pyogenes, Streptococcus anginosus, S. aureus
- Anaerobes, Bacteroides, and gram-negatives may also be seen
- All forms of orbital cellulitis carry a risk of severe morbidity and possible mortality and are therefore a true emergency:
- Permanent visual loss may occur
- May extend to subperiosteal space with abscess formation
- Cavernous sinus thrombosis and CNS infections may be life threatening
- Fungal infections are an uncommon but an even more lethal form particularly in the immunocompromised:
- Cerebrorhino-orbital phycomycosis (CROP)
- Rapidly fatal in 75% of cases:
- 80% of cases occur in patients with a recent episode of diabetic ketoacidosis
- Predisposing factor: Severe metabolic acidosis and immunocompromise
- Begins in the paranasal sinuses and proliferates in the blood vessels causing thrombosis and necrosis
- Bloody nasal discharge is common
- May present with evidence of necrosis of the palate and/or nasal mucosa
Pediatric Considerations
- Routine vaccinations including Hib and Pneumococcus have dramatically decreased periorbital and orbital cellulitis, but infections may still occur with these organisms particularly in younger children and those without at least 2 Hib vaccines
- Periorbital cellulitis is overall 5 times more common and typically occurs in children < 5 yr whereas orbital cellulitis is more common in children over 5 yr