Aims To describe the clinical features of orbital involvement arising from occult obstructive frontal sinus disease and to highlight key features to aid diagnosis.

Methods A retrospective review of the case notes of 15 patients who presented to three regional oculoplastics units over a 7-year period were reviewed. Patient demographics, clinical characteristics, relevant medical history, microbiology results, imaging, management and outcomes were assessed.

Results The mean age of our patients was 55 years. Pain was the presenting feature in 8 patients while 14 presented with upper lid swelling and redness. This swelling was medial in 60% and diffuse in 40% of patients. Proptosis was noted in 11 patients. The correct diagnosis was suspected in only 53% of patients at the time of first presentation to an ophthalmologist. The mean time from onset of symptoms to the time of correct diagnosis was 53 weeks (median 3 weeks). On direct questioning, eight patients reported a previous history of intermittent upper lid swelling and eight patients had a past history of sinusitis or frontal sinus trauma.

Conclusions We present a large series of patients with occult sinus disease presenting with orbital involvement. As patients with this potentially life-threatening condition are often misdiagnosed, we hope this paper draws the ophthalmologist's attention to key pearls in the history and examination to make a prompt diagnosis.