It is an infection of the soft tissues anterior to the orbital septum - this includes the eyelids, skin and subcutaneous tissue of the face, but not the contents of the orbit. This is in contrast to orbital cellulitis, which is an infection of the soft tissues behind the orbital septum, and is a much more serious infection.

Aetiology:

Infection usually spreads to the structures surrounding the orbit from other nearby sites, most commonly from breaks in the skin or local infections such as sinusitis or other respiratory tract infections.

The most frequently causative organisms are Staph. aureus, Staph. epidermidis, streptococci and anaerobic bacteria.

PC

• The patient presents with a red, swollen, painful eye of acute onset. They are likely to have symptoms associated with fever.

Signs:

• Erythema and oedema of the eyelids, which can spread onto the surrounding skin
• Partial or complete ptosis of the eye due to swelling
• Orbital signs (pain on movement of the eye, restriction of eye movements, proptosis, visual disturbance, chemosis, RAPD) must be absent in preseptal cellulitis - their presence would indicate orbital cellulitis

Significant differentials:

• Orbital cellulitis
• Allergic reaction

Investigations

• Bloods - raised inflammatory markers
• Swab of any discharge present