Orbital radiologic parameters of non-syndromic exorbitism patients in comparison with normal population

PURPOSE: To measure orbital dimension of patients with exorbitism and defining criteria for its diagnosis. METHODS: Twelve patients with non-syndromic exorbitism (NSE) were compared with 24 control samples by means of computed tomography scan (CT-scan) findings. The proptosis severity, lateral wall length, medial wall length, optic nerve straight length, lateral wall angle, ethmoidal sinus surface area, mid-interorbital distance, anterior interorbital distance, external orbital distance, inter-pupillary distance, and lateral wall curve cord were evaluated in order to define a criterion for NSE. RESULTS: Among eleven compared radiological parameters between the study and control groups, five parameters including lateral orbital wall angle (P = 0.02), mid-interorbital distance (P = 0.007), anterior inter-orbital distance (P < 0.001), inter-pupillary distance (P = 0.01), and proptosis severity (P < 0.001) were found to be significantly different between the study groups. Therefore, NSE could be diagnosed with lateral wall angle greater than 41.74°, mid-interorbital distance more than 31.84 mm, and anterior interorbital distance more than 25.90 mm, with a sensitivity of 91% and specificity of 71%. CONCLUSIONS: Using lateral wall angle, mid-interorbital distance, and anterior interorbital distance, we defined the criterion for diagnosis of NSE. Moreover, by focusing on parameters which play a role in developing exorbitism, we can determine the best approach for improvement of aesthetic and functional features of this condition.