Preorbital and orbital cellulitis are both infections that may present with swelling and erythema of the eyelid and periorbital tissues. The terms preseptal and septal may be used instead of periorbital and orbital respectively.
The key differential to these infections is whether there is infection posterior to the orbital septum, as this has serious consequences in terms of vision, serious CNS infection or cavernous sinus thrombosis.
Peri-orbital (also known as pre-septal) cellulitis is inflammation and infection of the superficial eyelid, usually from a superficial source.
The inflammation remains confined to the soft tissue layers superficial to the orbital septum and ocular function remains intact.
Peri-orbital cellulitis is much more common than orbital cellulitis. It is important to distinguish between Peri-orbital and orbital cellulitis because the complications, treatments, and outcomes of the two entities are very different.
Bacteria are the main cause of infection. Common organisms include Staphylococcus aureus, Streptococci, Haemophilus (unusual now with vaccination) and anaerobes.
Fungal infections have been seen in people with diabetic ketoacidosis or immunosuppression and recipients of organ transplantation, and are typically very aggressive and often fatal.
Sinusitis is the primary cause of Peri-orbital cellulitis and the infection usually spreads from the ethmoid sinuses. Less commonly, it spreads through the floor of the frontal sinus or through the roof of the maxillary antrum.
Orbital cellulitis is a potentially sight-threatening and life-threatening (but uncommon) ophthalmic emergency characterised by infection of the soft tissues behind the orbital septum. It can occur at any age, although it is most commonly seen in children. It usually originates from locally spreading infection.
Causative organisms are Staphylococcus, Streptococcus and Haemophilus species.
Upper respiratory tract infection
Impetigo (skin infection)
Trauma, sharp or blunt, around eye
Recent surgery around eye
Acute sinusitis (especially ethmoid sinusitis)
Trauma including orbital fracture
Clinical Features of Peri-Orbital Cellulitis
1. Eyelid swelling with or without erythema, unilateral ocular pain. 2. Leukocytosis may also occur in patients with peri-orbital (Pre-septal) cellulitis, but it is not a sensitive indicator of this infection. The clinical manifestations of pre-septal cellulitis should be distinguished from those of orbital cellulitis. 3. Serious complications are rare, reported complications include eyelid necrosis and amblyopia associated with delayed resolution of peri orbital swelling. 4. It is not clear whether untreated periorbital cellulitis leads to orbital cellulitis. 5. Peri-orbital cellulitis is mainly a clinical diagnosis, but the clinicians must be vigilant about orbital cellulitis which is a much more serious condition.
Clinical Features of Orbital Cellulitis
1. Orbital cellulitis is an infection involving the contents of the orbit posterior to the orbital septum which includes orbital fat and ocular muscles but not the globe.
2. Eyelid swelling with or without erythema. 3. Eye pain or tenderness - it could be deep eye pain. 4. Pain with eye movements. 5. In orbital cellulitis, in addition to the above features there might be ophthalmoplegia with or without diplopia, vision problem, chemosis, and leucocytosis. Fever is usually present.
When in doubt treat like orbital cellulitis. Patients must be hospitalised and treated with meningitis dose antibiotics.
Img Source: ENT UK