Assessment of periorbital (preseptal) and orbital (postseptal) cellulitis

Periorbital (preseptal) cellulitis and orbital (postseptal) cellulitis are infections near or around the eye with overlapping features. Periorbital cellulitis is often anterior and mild, while orbital cellulitis involves deeper tissues and is more severe. For distinguishing features of periorbital and orbital cellulitis, see Distinguishing features of periorbital (preseptal) and orbital (postseptal) cellulitis.

Note: Differentiating between periorbital and orbital cellulitis is important because orbital cellulitis is an emergency.

Differentiating between periorbital and orbital cellulitis is important because orbital cellulitis is an emergency; it can lead to orbital abscesses, extension of infection through the superior ophthalmic vein causing cavernous sinus thrombosis, intracranial infection and vision loss. If eyelid swelling precludes adequate eye examination, it may be difficult to differentiate between periorbital and orbital cellulitis; in such cases, additional investigations and escalation of therapy is required for children and systemically unwell adults (see Approach to managing orbital (postseptal) cellulitis).

Note: Children younger than 4 years are at increased risk of orbital cellulitis from posterior spread of periorbital cellulitis.

Spread of infection from the periorbital to orbital space is a possible complication of periorbital cellulitis, warranting close clinical review. Children younger than 4 years have an incomplete orbital septum so are at increased risk of orbital cellulitis from posterior spread of infection from the preseptal to orbital space.

Table 1. Distinguishing features of periorbital (preseptal) and orbital (postseptal) cellulitisChildren's Health Queensland Hospital and Health Service, 2023 The Royal Children's Hospital Melbourne (RCH), 2021 The Royal Victorian Eye and Ear Hospital (RVEEH), 2022 Watts, 2016
Feature	Periorbital cellulitis	Orbital cellulitis
Location	anterior to the orbital septum	posterior to the orbital septum possible intracranial spread
Incidence	common can occur in adults or children	rare more common in children
Systemic features	systemically well; fever is uncommon	systemically unwell; fever is common features of intracranial involvement (eg severe headache, nausea, vomiting) may be present
Eyelid appearance	unilateral swelling and inflammation	if present, swelling and inflammation is unilateral
Conjunctival appearance	normal	chemosis
Orbital signs	normal	proptosis diplopia is a typical early sign painful, tender or restricted eye movements
Optic nerve function	normal	severe cases may have decreased: visual acuity colour vision red saturation brightness visual fields may be abnormal
Potential causes	eyelid trauma (eg insect bite) spread of infection from contiguous structures: sinus infection infected chalazion or hordeolum dacryocystitis	most commonly, spread of infection from paranasal sinuses complication of: orbital trauma surgery foreign body dacryocystitis dental or facial infection endogenous spread of organisms in patients with immune compromise