Diagnosis of an unusual orbital abscess following sub-Tenon's steroid injection: a case report.

Orbital abscesses are caused by infection within or near the orbit and show obvious signs of pain, proptosis and raised inflammatory markers. Diagnosis is based on clinical features and radiological imaging, and requires early antibiotics and often surgical drainage to save vision. Sub-Tenon's injections of triamcinolone acetonide (TA) have caused localized infections in previous reports, which have responded to therapeutic interventions. Here we report a case where a delayed presentation of an orbital abscess secondary to sub-Tenon's TA for persistent post-operative cystoid macular oedema, without obvious signs of infection, rapidly progressed to cause orbital compartment syndrome. Despite treatment, the patient lost complete vision in the affected eye. This case discusses the rare and unusual cause of abscess formation and a diagnostic dilemma.