Effect of orbital volume in unilateral orbital fracture on indirect traumatic optic neuropathy

Purpose This retrospective study aimed to analyze the relationship between the volume of the fractured and the normal orbit in patients with unilateral orbital fractures with and without indirect traumatic optic neuropathy (TON). Subjects Data of 25 patients with unilateral orbital fractures who underwent computer tomography between January 2016 and December 2020 were investigated. Emergency imaging was performed within 2 hours of arrival at the emergency room. The subjects were categorized into two groups: unilateral orbital fractures with and without TON. Methods and measures The assessment of TON was performed during a comprehensive ophthalmologic examination by an ophthalmologist. The stereographic orbit was reconstructed, and the volume was calculated. Other variables examined included age, sex, and cause of orbital trauma. The variables were compared using paired t-tests. Statistical significance was set at p < 0.05. Results The orbital volume of the non-fractured orbit was 27.50 +/- 2.26 and 27.48 +/- 2.64 cm(3) in the groups with and without TON, respectively. The average volume of the fractured orbit in the TON group was 27.78 +/- 2.56 cm(3), and there was no significant volumetric difference between the fractured and non-fractured sides in this group. However, the average volume of the fractured orbit without TON was 28.76 +/- 3.18 cm(3), larger than that of the non-fractured orbit (p = 0.016). Conclusions Non-expansion of the fractured orbit was a risk factor for indirect TON in patients with unilateral orbital fractures. Volumetric analysis from primary imaging would expedite the diagnosis and treatment of TON, resulting in optimal outcomes.