Introduction

Most external eye infections do not require any specific investigations. However the following investigations should be carried out:

Baseline observations

As with all infections, a set of baseline observations (including temperature and capillary blood glucose) are useful to identify the systemically unwell.

Preseptal cellulitis, hordeolum, chalazion, blepharitis, and dacryocystitis are all clinical diagnoses.

Orbital cellulitis

Orbital cellulitis should be investigated along the lines of other severe infections. Swabs should be taken from any local wounds or discharge from sinuses. Blood should be taken according to local guidelines for sepsis, including inflammatory markers, lactate, and blood cultures.

Further investigation of orbital cellulitis would normally be guided by the ophthalmology team after admission:

• Blind aspiration of the orbit should not be performed. The technique rarely yields diagnostic samples, and carries a significant morbidity
• If there is any evidence of meningism to suggest spread of infection beyond the orbit, a lumbar puncture should be performed with cerebrospinal fluid (CSF) sent for urgent gram stain
• High resolution CT scanning of the orbits can help to confirm the diagnosis, and will indicate spread to deeper structures and guide the need for surgical management

Learning Bite

With the exception of orbital cellulitis no investigations, other than baseline observations, should be routinely performed in the majority of patients with an external eye infection.