Analysis of the Results of Reconstructive and Restorative Operations in Post-Traumatic Orbital Defects by Computer Simulation

Treatment of patients with post-traumatic orbital defects is relevant problem of ophthalmology and maxillofacial surgery. Residual diplopia or dislocation of the eyeball leads to disability, social maladaptation and development of psychoemotional disorders in patients. In this paper, we present an evaluation of treatment of patients with posttraumatic orbital wall defects based on the retrospective comparative analysis of CT data by computer simulation before and after reconstruction. When comparing the volume of the injured orbits before and after the operation (average volume difference was 2.7 ± 0.9 cm3), a significant improvement was found in terms of recovery of the orbital volume. The factors influencing the treatment effectiveness were determined based on the calculation of the volume of the orbits on the healthy and injured side in the software environment before and after the reconstruction. The causes of the detected cases of incomplete recovery of the orbital volume were analyzed. The solution to the problem of restoring the orbital volume is in the plane of restoring the geometry of the orbit because previous adaptation of the shape of the standard plate to its anatomical structure with overlapping defect on the stereolithographic model provided the best end result. Conclusions. Personalized adaptation of the implants to the shape of the orbit or individual production thereof can increase the accuracy of the orbital volume restoration, which can increase the effectiveness of eliminating complications such as enophthalmos and diplopia. The effectiveness of treatment of post-traumatic orbital defects by traditional methods directly depends on the severity of the damage, the degree of which determines the magnitude of the change in the orbital volume. However, the greater is the volume of the orbit changes as a result of the injury, the worse is the prognosis for its recovery. Development of the ways to individualize implants and evaluate their effectiveness is an important area for further research. Keywords: post-traumatic orbital defects, reconstructive surgery, computer simulation.

Preliminary Outcomes Following Application Of The Real-Time Navigation System Combined With Intraoperative Three-Dimensional C-Arm Computed Tomography For Zygomatico-Orbital Fracture Reconstruction

This study analyzed the outcomes of zygomatico-orbital fracture reconstruction using the real-time navigation system with intraoperative three-dimensional (3D) C-arm computed tomography (CT). Fifteen patients with zygomatico-orbital or isolated orbital/zygoma fractures were enrolled in this prospective cohort. For zygoma reduction, the displacement at five key sutures and the differences between preoperative and intraoperative CT images were compared. For orbital reconstruction, the bilateral orbital volume differences in the anterior, middle, and posterior angles over the medial transitional buttress were measured. Two patients required implant adjustment once after the intraoperative 3D C-arm assessment. On comparing the preoperative and postoperative findings for the zygoma, the average sum of displacement was 19.48 (range, 5.1–34.65) vs. ±1.96 (0–3.95) mm (P < 0.001) and the deviation index was 13.56 (10–24.35) vs. 2.44 (0.6–4.85) (P < 0.001). For the orbit, the mean preoperative to postoperative bilateral orbital volume difference was 3.93 (0.35–10.95) vs. 1.05 (0.12–3.61) mm3 (P <0.001). The mean difference in the bilateral angles at the transition buttress was significantly decreased postoperatively at the middle and posterior one-third. The surgical navigation system with the intraoperative 3D C-arm can effectively improve the accuracy of zygomatico-orbital fracture reconstruction and decrease implant adjustment times.

Orbital volume, ophthalmic sequelae and severity in unilateral coronal synostosis

Purpose Unilateral coronal synostosis (UCS) results in an asymmetrical skull, including shallow and asymmetrical orbits, associated with reduced orbital volume and high prevalences of ophthalmic sequelae. Aim is to link orbital volumes in patients with UCS to severity according to UCSQ (Utrecht Cranial Shape Quantifier) and presence of ophthalmic sequelae. Methods We included preoperative patients with UCS (≤ 18 months). Orbital volume was measured on CT scans by manual segmentation (Mimics software (Materialise, Leuven, Belgium)), and severity of UCS was determined by UCSQ. Orbital volume of affected side was compared to unaffected side using Wilcoxon signed rank test. Orbital volume ratio was calculated (affected/unaffected volume) and compared to the category of UCSQ by Kruskal-Wallis test. Opthalmic sequelae were noted. Results We included 19 patients (mean age 7 months). Orbital volume on affected side was significantly lower (p = 0.001), mean orbital volume ratio was 0.93 (SD 0.03). No significant differences in group means of orbital volume ratio between different levels of severity of UCSQ were found (Kruskal-Wallis H (2) = 0.873; p > 0.05). Ophthalmic sequelae were found in 3 patients; one had adduction impairment and strabismus (mild UCS), one had astigmatism (moderate UCS), and one had abduction impairment (on both ipsi- and contralateral side) and vertical strabismus (severe UCS). Conclusion No association between orbital volume ratio and severity of UCS was found. Side-to-side asymmetry in orbital volume was noted. No association between either preoperative orbital volume ratio or severity of UCS and the presence of preoperative ophthalmic sequelae was found.

Normative Measurement of Orbital Structures in Computed Tomography

Introduction Normal orbital dimensions are important for diagnosing orbital pathologies. Computed tomography (CT) of the orbit is an important modality offering high accuracy for precise measurements of orbit. The study was disbursed to ascertain criteria for the normative values of the various orbital dimensions using computed tomography in patients visiting Tribhuvan University Teaching Hospital, Kathmandu. MethodsOrbital volume, ocular diameter, length of the interzygomatic line (IZL), the distance of the posterior extent of the globe from the interzygomatic line, globe position, diameters of extraocular muscles (medial, lateral, superior group, and inferior rectus) and lens density were measured in each eye of 172 patients undergoing CT examination of paranasal sinuses. The correlations with age and sex were also analyzed. ResultsMean values (mean±SD) of orbital volume, ocular diameter, IZL, globe position and lens density were 24.54±2.57 cm3, 2.44±0.22 cm, 94.3±6.2 mm, 12.3±2.4 mm and 141.43±16.62 HU respectively. Mean diameters of extraocular muscles were 3.67± 0.52 mm, 3.36± 0.50 mm, 3.74±0.42 mm and 3.87±0.38 mm for medial rectus, lateral rectus, inferior rectus and the superior group respectively. There was no significant age and gender difference in most of the measurements. There was significant positive correlation of age with lens density, orbital volume and ocular diameter (p<0.05). ConclusionNormative data of different orbital measurements were obtained. The present result may help radiologists and ophthalmologists to accurately assess various orbital parameters, particularly in Nepalese populations.