Is the Mirroring Technology Reliable in the Use of Computer-Aided Design for Orbital Reconstruction? Three-Dimensional Analysis of Asymmetry in the Orbits

Abstract

Background: Reconstruction of the orbital area remains a challenge in many cases. The recently introduced mirroring technology provides surgeons with patient-specific information for accurate orbital reconstruction; its premise is that the three-dimensional anatomy of craniofacial bone is symmetric. The purpose of this study was to verify this premise of the mirroring technology by assessing three-dimensional asymmetry. Methods: Facial computed tomographic data of 104 patients were imported into iPlan software. Four reference points (i.e., zygomaticofrontal suture, frontomaxillary suture, infraorbital foramen, and optic canal) were set, and the three-dimensional distances from these points to the anterior nasal spine on the mirroring plane were calculated. In addition, the orbital cavity volume and the three-dimensional distances from point optic canal to the other reference points were calculated for the assessment of the orbit anatomy. Three plastic surgeons performed these processes independently. Results: No statistically significant difference was found in the three-dimensional distances between anterior nasal spine and the four reference points bilaterally. Also, no statistically significant difference in the three-dimensional distances between the point representing the optic canal and other reference points was detected bilaterally. Orbital cavity volume showed a mild asymmetry, but the discrepancy was acceptable for computer-aided design applications. For all reference points, the maximum value of the 95 percent CI was less than 1.4 mm. Conclusions:The three-dimensional location of the orbits and the three-dimensional anatomy of the orbit were symmetric. Thus, the mirroring technology could be a reliable first step in computer-aided design, computer-assisted surgery, and navigation-assisted surgery.

Prediction of Permanent Enophthalmos Using 3-Dimensional Integral Model in Blowout Fractures

“…The volume in males is usually 2.0 to 3.3 cm 3 larger than in females 24,25 . In this study, the mean orbital volume of the 768 orbits was 28.65 cm 3 , which is analogous to that obtained in our previous study, where we analyzed the orbits of 104 normal subjects using the same software 19 …”

“…Through our previous study, we confirmed that bilateral orbits are symmetrical, making it possible to calculate the change in orbital volume using the unaffected orbit on the opposite side as a reliable reference 19–23 . The methods used to measure orbital volume vary among the previous studies.…”

“…Through our previous study, we confirmed that bilateral orbits are symmetrical, making it possible to calculate the change in orbital volume using the unaffected orbit on the opposite side as a reliable reference. [19][20][21][22][23] The methods used to measure orbital volume vary among the previous studies. Therefore, the value of the normal orbital volume varied widely (20.2-30.8 cm 3 ); however, a value of 24.5 cm 3 was found in the majority of studies.…”

“…24,25 In this study, the mean orbital volume of the 768 orbits was 28.65 cm 3 , which is analogous to that obtained in our previous study, where we analyzed the orbits of 104 normal subjects using the same software. 19 In numerous studies, the average value of the area of 2 adjacent slices in a CT scan image was multiplied by the thickness of the slice to obtain the volume of one slice, and the sum of the volumes of all the slices was calculated. 26 However, this calculation method takes time, and the results are not reproducible because the area has to be calculated by drawing a new area on the CT scan for every measurement.…”

Patient-specific implants in orbital reconstruction

“…2, http://links.lww.com/COOH/A47). Mirroring techniques have been widely described for orbital reconstruction, and right-versus-left volume discrepancies are insignificant such that the contralateral side usually provides a reliable reference point [11,12]. The three-dimensional superimposition should be optimized to attain maximal skull base registration.…”