Sex-related and racial variations in orbital floor anatomy

Predictive factors of development of dysthyroid optic neuropathy among individuals with thyroid-eye disease

PURPOSE

Dysthyroid optic neuropathy (DON) is a severe visual loss condition in thyroid eye disease (TED). This study aimed to identify factors affecting moderate-to-severe TED or DON in Thai populations.

METHODS

We retrospectively reviewed the records of 230 TED patients at Rajavithi Hospital between January 1, 2017, and October 31, 2022.

RESULTS

Mild, moderate-to-severe TED, and DON were found in 60.43%, 22.61%, and 16.96% of participants, respectively. Female predominance was noted in all groups. The proportion of older age, hyperthyroidism, current smokers, and type 2 diabetes mellitus (T2DM) participants were significantly higher in the DON group. Multivariable logistic-regression analysis revealed that hyperthyroidism and current smoking significantly increased the risk of developing moderate-to-severe TED (OR = 3.001, p = 0.010, and OR = 4.153, p = 0.015, respectively). Exophthalmos was the strongest predictor (OR = 6.834, p < 0.001). Regarding DON risk factors, older age (≥55 years) had OR = 3.206 (p = 0.003), hyperthyroidism had OR = 3.228 (p = 0.005), and being a current smoker had OR = 3.781 (p = 0.011). T2DM posed the greatest risk of DON development (OR = 4.111, p = 0.004).

CONCLUSIONS

Hyperthyroidism and current smoking are significant risk factors for moderate-to-severe TED and DON. TED patients with diabetes mellitus or older age should be closely monitored and informed about their risk of developing DON.

Quantification of global orbital shape variation

The complex anatomy of the orbit generates a complex orbital shape that can only be quantified approximatively by classic linear measurements such as maximum width and height. There is no global three-dimensional quantification of variations in orbital shape. The purpose of this study was to develop a method to quantify a global three-dimensional orbital shape variation in a healthy population and to test a series of explanatory factors. We investigated the hypotheses that orbital shape is related to gender(H1), orbital size(H2) and/or age(H3). Medical computed tomography(CT) images of 60 adult individuals were studied. The study sample consisted of 30 males and 30 females with a mean age of 25.1 years. Four anatomical landmarks and 140 semi-landmarks were measured on both positive and negative 3D reconstructed orbits and analyzed with geometric morphometrics. A principal component analysis(PCA) was computed to define a morphological space. Shape variation was visualized using vector distance maps and diagrams. The greatest variation was seen in the length of the superior orbital fissure. There was a gradient in terms of orbital shape ranging from short, wide orbits to tall, narrow orbits. The analysis did not highlight any significant age-, gender- or size-related impact in terms of orbital shape variation. Future avenues to explore include the study of other potential explanatory factors such as the different embryological origins of the orbital bones, the passage of vessels and nerves, and ethnic origins. This method can also be applied to the study of pathological orbits.

Pressure Onto the Orbital Walls and Orbital Morphology in Orbital Floor or Medial Wall Fracture: A 3-Dimensional Printer Study

The purposes of this study were to compare the pressure onto the orbital floor and medial orbital wall between 3-dimensional printer skull models with unilateral orbital floor and medial orbital wall fractures and to compare the morphology of the orbital floor and medial orbital wall between patients with unilateral orbital floor and medial orbital wall fractures. The skull models were created based on computed tomographic (CT) data obtained from every 10 patients with unilateral orbital floor and medial orbital wall fractures. The orbital spaces of these models were filled with silicone, the silicone surface was pushed down, and pressures onto the orbital floor and the medial orbital wall were measured. On preoperative computed tomographic images taken in the same 20 patients, the superior and lateral bulges of the orbital floor and medial orbital wall were measured, respectively. The measurements were done on the unaffected sides. Consequently, the pressure onto the orbital floor was significantly higher in the orbital floor fracture models than in the medial orbital wall fracture models, although the pressure onto the medial orbital wall was not significantly different between the models. As for the morphologic study, the superior bulge of the orbital floor was higher in the orbital floor fracture group than in the medial orbital wall fracture group. The results of this study indicate that since the orbital floor with a high superior bulge receives high hydraulic pressure, patients with a high superior bulge have a greater risk of orbital floor fracture.

Is the Pre-Shaping of an Orbital Implant on a Patient-Specific 3D-Printed Model Advantageous Compared to Conventional Free-Hand Shaping? A Systematic Review and Meta-Analysis

This study aimed to perform a systematic review and meta-analysis to compare pre-shaped implants on a patient-specific 3D-printed (3DP) model to manual free-hand shaping (MFS) for orbital wall reconstruction. The PRISMA protocol was followed in this study, and the review was registered in the PROSPERO database (CRD42021261594). A search was conducted in MEDLINE (PubMed), Embase, Cochrane Library, Clinicaltrials.gov, Google Scholar, and the grey literature. Ten articles were included, and six outcomes were analyzed. In total, 281 patients were in the 3DP group and 283 were in the MFS group. The studies had an overall high risk of bias. 3DP models resulted in a better accuracy of fit, anatomical angle reproduction, and defect area coverage. The correction of orbital volume was also superior with statistical significance. There was a higher percentage of the correction of enophthalmos and diplopia in the 3DP group. Intraoperative bleeding and hospital stay were reduced in the 3DP group. The meta-analysis of operative time showed a reduction in the average operative time by 23.58 min (95% CI: -43.98 to -3.19), which was statistically significant (t(6) = -2.8299, p = 0.0300). The 3DP models appear advantageous for an accurate orbital wall reconstruction, with fewer complications than those for conventional free-hand-shaped implants.

Clinical Results According to Inferior Oblique Manipulation in Patients with Inferomedial Blowout Fracture Involving the Orbital Strut

Background

Detachment of the inferior oblique muscle may be necessary under certain circumstances to repair a large inferomedial orbital fracture involving the orbital strut. This study aimed to evaluate the outcomes of patients who underwent surgeries with and without inferior oblique muscle reattachment after its detachment to repair the orbital wall fractures.

Methods

Forty patients who underwent repair of combined floor and medial orbital wall fracture involving the orbital strut at a single tertiary institution between January 2014 and December 2020 were reviewed. Groups 1 and 2 comprised 20 patients each, who underwent surgery with inferior oblique muscle detachment without and with reattachment, respectively, and were followed up for at least 6 months postoperatively. Enophthalmos, Goldmann diplopia test, alignment test, ocular motility test, and orbital inferomedial angle ratio were the outcome measures.

Results

Statistically significant improvement was observed in ocular motility, diplopia, and enophthalmos postoperatively at the 1- and 6-month follow-up (p < 0.01). The mean postoperative inferomedial angle ratio (102.28 ± 10.62%) was improved significantly compared with the preoperative inferomedial angle ratio (115.61 ± 4.38%) (p = 0.004) in all patients. After surgery, inferior oblique muscle underaction was observed in seven and six patients in groups 1 and 2, respectively, which was associated with preoperative extraocular movement limitation and strabismus. Two patients showed diplopia in both groups at the last follow-up; they had inferior oblique muscle underaction but no enophthalmos.

Conclusion

Orbital fracture repair with or without inferior oblique muscle reattachment was clinically effective and safe; however, patients with preoperative strabismus and extraocular motility limitation should be informed of the increased risk of postoperative complications.

Sensory change and recovery of infraorbital area after zygomaticomaxillary and orbital floor fractures

BACKGROUND

To compare the sensory change and recovery of infraorbital area associated with zygomaticomaxillary and orbital floor fractures and their recoveries and investigate the factors that affect them.

METHODS

We retrospectively reviewed 652 patients diagnosed with zygomaticomaxillary (n= 430) or orbital floor (n= 222) fractures in a single center between January 2016 and January 2021. Patient data, including age, sex, medical history, injury mechanism, Knight and North classification (in zygomaticomaxillary fracture cases), injury indication for surgery (in orbital floor cases), combined injury, sensory change, and recovery period, were reviewed. The chi-square test was used for statistical analysis.

RESULTS

Orbital floor fractures occurred more frequently in younger patients than zygomaticomaxillary fractures (p< 0.001). High-energy injuries were more likely to be associated with zygomaticomaxillary fractures (p< 0.001), whereas low-energy injuries were more likely to be associated with orbital floor fractures (p< 0.001). The sensory changes associated with orbital floor and zygomaticomaxillary fractures were not significantly different (p= 0.773). Sensory recovery was more rapid and better after orbital floor than after zygomaticomaxillary fractures; however, the difference was not significantly different. Additionally, the low-energy group showed a higher incidence of sensory changes than the high-energy group, but the difference was not statistically significant (p= 0.512). Permanent sensory changes were more frequent in the high-energy group, the difference was statistically significant (p= 0.043).

CONCLUSION

The study found no significant difference in the incidence of sensory changes associated with orbital floor and zygomaticomaxillary fractures. In case of orbital floor fractures and high-energy injuries, the risk of permanent sensory impairment should be considered.

One-point versus two-point fixation in the management of zygoma complex fractures

Background

The treatment of zygoma complex fractures is of crucial importance in the field of plastic surgery. However, surgical methods to correct zygoma complex fractures, including the number of fixation sites, differ among operators. Although several studies have compared two-point and three-point fixation, no comparative research has yet been conducted on one-point versus two-point fixation using computed tomography scans of surgical results. Therefore, the present study aimed to address this gap in the literature by comparing surgical results between one-point and two-point fixation procedures.

Methods

In this study, we randomly selected patients to undergo surgery using one of two surgical methods. We analyzed patients with unilateral zygoma complex fractures unaccompanied by other fractures according to whether they underwent one-point fixation of the zygomaticomaxillary buttress or two-point fixation of the zygomaticomaxillary buttress and the zygomaticofrontal suture. We then made measurements at three points—the zygomaticofrontal suture, inferior orbital wall, and malar height—using 3-month postoperative computed tomography images and performed statistical analyses to compare the results of the two methods.

Results

All three measurements (zygomaticofrontal suture, inferior orbital wall, and malar height) showed significant differences (p<0.05) between one-point and two-point fixation. Highly significant differences were found for the zygomaticofrontal suture and malar height parameters. The difference in the inferior wall measurements was less meaningful, even though it also reached statistical significance.

Conclusion

Using three parameters in a statistical analysis of imaging findings, this study demonstrated significant differences in treatment outcomes according to the number of fixations. The results indicate that bone alignment and continuity can be achieved to a greater extent by two-point fixation instead of one-point fixation.

3-D cephalometry of the the orbit regarding endocrine orbitopathy, exophthalmos, and sex

Purpose

This study aimed at evaluating the orbital anatomy of patients concerning the relevance of orbital anatomy in the etiology of EO (endocrine orbitopathy) and exophthalmos utilizing a novel approach regarding three-dimensional measurements. Furthermore, sexual dimorphism in orbital anatomy was analyzed.

Methods

Orbital anatomy of 123 Caucasian patients (52 with EO, 71 without EO) was examined using computed tomographic data and FAT software for 3-D cephalometry. Using 56 anatomical landmarks, 20 angles and 155 distances were measured. MEDAS software was used for performing connected and unconnected t-tests and Spearman´s rank correlation test to evaluate interrelations and differences.

Results

Orbital anatomy was highly symmetrical with a mean side difference of 0.3 mm for distances and 0.6° for angles. There was a small albeit statistically significant difference in 13 out of 155 distances in women and 1 in men concerning patients with and without EO. Two out of 12 angles showed a statistically significant difference between female patients with and without EO. Regarding sex, statistically significant differences occurred in 39 distances, orbit volume, orbit surface, and 2 angles. On average, measurements were larger in men. Concerning globe position within the orbit, larger distances to the orbital apex correlated with larger orbital dimensions whereas the sagittal position of the orbital rim defined Hertel values.

Conclusion

In this study, little difference in orbital anatomy between patients with and without EO was found. Concerning sex, orbital anatomy differed significantly with men presenting larger orbital dimensions. Regarding clinically measured exophthalmos, orbital aperture anatomy is an important factor which has to be considered in distinguishing between true exophthalmos with a larger distance between globe and orbital apex and pseudoexophthalmos were only the orbital rim is retruded. Thus, orbital anatomy may influence therapy regarding timing and surgical procedures as it affects exophthalmos.