Ethnic variation in medial orbital wall anatomy and its implications for decompression surgery

To describe the inter-ethnic variation in medial orbital wall anatomy between Chinese, Malay, Indian and Caucasian subjects

Observational research using computed tomography (CT) in a single centre. Gender and laterality were matched in 20 individuals of each race. We excluded subjects younger than 16 years and those with orbital pathology. OsiriX version 8.5.1 (Pixmeo., Switzerland) and DICOM image viewing software CARESTREAM Vue PACS (Carestream Health Inc., USA) were used to measure the ethmoidal sinus length, width, and volume, as well as the angle between the medial orbital wall and the floor, and the location of the posterior ethmoid sinus in relation to the posterior maxillary wall. The Statistical Package for Social Sciences, version 25.0, was used to conduct the statistical analyses (IBM, USA).

Results

Each group had 12 men (60 percent), with no significant age difference (p = 0.334–0.994). The mean ethmoid sinus length in Chinese, Malay, Indian, and Caucasian participants, using the Chinese as a reference, was 37.2, 36.9, 38.0, and 37.4mm, respectively; the mean breadth was 11.6, 10.5, 11.4,
and 10.0mm (p = 0.020); and the mean ethmoid sinus volume was 3362, 3652, 3349, and 3898mm3. The mean medial orbital wall and floor angles were 135.0, 131.4, 131.0, and 136.8 degrees, respectively, and the mean posterior ethmoid sinus relative position to the posterior maxillary wall was 2.0, -0.2, -1.5, and 1.6mm (p = 0.003).