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Emile Sharifi, Thao Phuong Le, Katherine Howe, Lee Mitsumori, Arash Jian-Amadi; Relationship of Pre-orbital and Orbital Volume to Blowout Fractures. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2305.
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© ARVO (1962-2015); The Authors (2016-present)
This study explores the underlying pathogenesis of orbital blowout fractures as it relates to pre-orbital and orbital tissue volumes.
Fifty maxillofacial CT scans of patients who sustained unilateral orbital blowout fractures due to blunt trauma and a control group of 50 maxillofacial CT scans in patients who sustained open globe injury without fracture were retrospectively identified from case logs. The pre-orbital and orbital soft tissue volumes of the non-traumatized orbit of each scan were measured on the axial CT images using commercially available post-processing software. Orbital volume was defined as all content posterior to the orbital rim and up to, but not including the optic canal. Pre-orbital volume was defined as all tissues directly anterior to, and contained within imaginary lines projected perpendicularly from the orbital rim. All measurements were done by one of two authors (ES and TPL) with a crossover group to assess inter-user reproducibility.
The average measured pre-orbital and orbital volumes in the fracture group were 13.1 cm3 +/- 3.6 and 24.3 cm3 +/- 2.4. The average difference between measured pre-orbital and orbital volumes was 11.3 cm3, with a pre-orbital/orbital volume ratio of 2.0 and total volume (pre-orbital + orbital volume) of 37.3 cm3. In the non-fracture group, the measured pre-orbital and orbital volumes were 14.3 cm3 +/- 3.5 and 26.1 cm3 +/- 2.9, with an average difference of 11.9 cm3, a volume ratio of 1.9, and a total volume of 40.4 cm3. Patients with blowout fractures had on average 1.3 cm3 less pre-orbital tissue (p =0.04) and 1.8 cm3 less orbital tissue (p < 0.001) compared to patients without fractures.
The distribution of orbital tissue volume appears to be inversely correlated with the degree of bony structural damage in patients suffering unilateral blunt trauma.
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