[Orbital volume measurement of enophthalmos of orbital blowout fractures].

OBJECTIVE: To measure the volumetric changes of enophthalmos of orbital blowout fractures, and to study the relation between the change of the orbital volume and the degree of enophthalmos.

METHODS: In 16 patients with enophthalmos of orbital blowout fractures, the measurement of orbital volume was carried out during 3 months to 2 years after injury by using the computed tomography (CT), computer image processing and computer orbital three-dimensional measuring method. The relation between the orbital volume discrepancy and enophthalmos was assessed by using Pearson correlation coefficients.

RESULTS: There were significant linear correlation between the increment of the orbital volume and the degree of enophthalmos (r = 0.95, P < 0.001), with each 1.0 cm(3) increment in bony volume causing approximately 0.9 mm of enophthalmos.

CONCLUSIONS: Orbital blowout fractures can expand the orbital volume. The measurement of orbital volume may predict the risk and the final degree of the enophthalmos at the late stage, thus it may provide useful information in surgical intervention to estimate the size and volume of the orbital implant for an individual case.