Digital evaluation of orbital development after self-inflating hydrogel expansion in Chinese children with congenital microphthalmia

Biomechanical Analysis of Orbital Development: A Finite Element Analysis by an Experimentally Validated Model

AIMS

Constructing orbital finite element models capable of simulating the development process and analyzing the biomechanical mechanism.

METHODS

Four normal orbits from 1-month-old New Zealand white rabbits were used in this study. Toshiba Aquilion Prime was used to determine the computed tomography scan and direct orbital pressure manometry using an improved manometer based on the TSD104 pressure sensor transducer. The finite element analysis was conducted using the ANSYS Workbench platform.

RESULTS

The biomechanics of each orbital wall improved to varying degrees as the rabbit orbit grew and developed. The von Mises stress in both rabbits initially concentrated at the lower edge of the posterior orbital wall, expanded to the entire orbit, and ultimately became more significant in the biomechanics of the region that consisted of the posterior orbital and superior orbital walls. During the expansion phase, the biomechanics of both rabbits gradually developed from the nasal side to the occipital side for radial displacement. It is evident that the finite element model is a good fit for simulating the physiological development of the rabbit orbit. The maximum radial displacement and maximum von Mises stress appeared 2 intermissions during the development of the orbit, at about 50 to 60 days and 80 to 90 days.

CONCLUSION

This study establishes a theoretical foundation for the creation of a biomechanical model of human orbital development by offering the first finite element model to simulate orbital development and analyze the biomechanical mechanism of orbital pressure on orbital development.

Determining Asymmetry Thresholds in Anophthalmia/Microphthalmia Using a Three-dimensional Animated Model

PURPOSE

Congenital microphthalmia and anophthalmia are rare development disorders with underdevelopment of the orbital region, resulting in asymmetry of the face. No clear guidelines exist to determine when these deviations are acceptable.

METHODS

The face of a healthy 6-year-old child was three-dimensionally scanned. On this scan, we modeled various incremental degrees of facial asymmetries using three-dimensional modeling software. We modeled for smaller palpebral fissures, sunken eyes, and downward displacement of the eye. We also tested whether adjusting the vertical palpebral fissure height in relation to the horizontal palpebral fissure width affected perception. A total of 22 videos were created in which the model turned the head horizontally and vertically. We created a questionnaire asking raters how acceptable the face is, on a linear scale from 0 to 10.

RESULTS

Results showed a correlation between the degree of asymmetry and the acceptability score of the raters. Enophthalmos of ≥6 mm, palpebral fissure width ≤79% compared with the other eye, and 2 mm or more downward displacement of the eye resulted in a significant different acceptability score. The desire for correction was strongly increased when these thresholds were exceeded. Adjusting the vertical palpebral fissure height to the horizontal palpebral fissure width resulted in a worse acceptability score.

CONCLUSION

A unilateral sunken eye (enophthalmos) of 6 mm or more, asymmetric horizontal palpebral fissure length of ≤79%, and a lower position of one eye of more than 2 mm resulted in unacceptable judgment. These data can be used to evaluate treatment outcome in children treated for congenital microphthalmia and anophthalmia.

Stepwise self-inflating hydrogel expansion for congenital anophthalmia and blind microphthalmia: Over 15 years' experience in China

BACKGROUND

Self-inflating hydrogel expanders have been used to treat anophthalmia and blind microphthalmia. This study aimed to investigate the long-term outcomes of treatment with self-inflating hydrogel expanders for congenital anophthalmia and blind microphthalmia.

METHODS

In this retrospective study, the medical records of 161 patients with anophthalmia and blind microphthalmia who underwent hydrogel expansion were reviewed. We measured the palpebral fissure height (PFH), palpebral fissure length (PFL), and distance between the inner canthal and mid-nasal line (ICMN) before and after surgery. Cox regression analysis was conducted to determine which variables were related to the implantation of spherical expanders following hemispherical expander implantation.

RESULTS

After treatment, the PFH and PFL increased significantly (p < 0.001). Complications including expander migration and extrusion occurred in 15 cases. Five patients needed enucleation or further dermis fat graft implantation because of insufficient expansion. The necessity for further spherical expansion was substantially related to a relative axial length (rAL) <0.5 (p = 0.007).

CONCLUSION

Self-inflating hydrogel expansion can significantly increase the lid fissure. The occurrence of complications is rare, and surgical intervention can effectively address them. Abnormal eyes with a rAL of less than 0.5 demonstrate a higher possibility of needing additional orbital expansion.

Correlation Between the Computed Tomography and 3D Scanning System-Based Periorbital Morphology of Children with Congenital Microphthalmia

PURPOSE

This article aimed to explore the correlation between the periorbital morphology determined using a 3D scanning system and CT in congenital microphthalmia.

METHODS

Fifty-two children with microphthalmia aged 0-6 were enrolled in this study. All the participants were subjected to orbital CT scans and 3D scanning. The CT and 3D scanning images were separately processed to obtain the orbital and facial parameters. Multivariate regression was used to analyze the correlation between 3D parameters and orbital volume.

RESULTS

The orbital volume of the affected side (15.25 ± 3.35 cm3) was generally smaller than the unaffected side (18.58 ± 2.65 cm3, p < .001). Based on CT, at all ages, the parameters of the unaffected orbit were greater than the affected side. In the 3D scanning and 3D reconstruction based on CT, both unaffected and affected sides were highly correlated. A multiple linear regression equation including three 3D scanning factors was obtained for the orbital volume (R2 = 0.808, p < .001).

CONCLUSIONS

The retarded orbital volume could be estimated by the parameters based on 3D scanning, along with axial length. In the follow-up stage, 3D scanning can be a novel alternative method to assess the degree of orbital growth retardation in congenital microphthalmia.

Socket expansion with conformers in congenital anophthalmia and microphthalmia

PURPOSE

To report the outcomes of acrylic conformer-assisted socket expansion in congenital anophthalmia and microphthalmia.

METHODS

In this noncomparative, interventional case series, the medical records of 24 eyes of 18 consecutive patients with congenital anophthalmia (n = 3), clinical anophthalmia (n = 8), and microphthalmia (n = 13) were reviewed retrospectively. Twelve cases were unilateral; 6 were cases bilateral (3 clinical anophthalmia and 3 microphthalmia). Serial socket expansion with progressively larger acrylic conformers was managed in clinic. Horizontal palpebral fissure (HPF) width was graded as good (final HPF ≥20 mm, or interocular difference ≤2 mm for unilateral cases), fair (17-19 mm, or 3 mm interocular difference), or poor (<17 mm, or ≥4 mm difference).

RESULTS

The mean initial lid lengths in anophthalmia, clinical anophthalmia, and microphthalmia were 11.0, 12.4, and 16.9, increasing to 21.0, 19.9, and 22.2, respectively, over a mean period of 51 months. Mean age at the initiation of treatment was 19 months (range, 1-78). Percentage increases in lid length were 90.9%, 61.2%, and 31.3% in anophthalmia, clinical anophthalmia, and microphthalmia, respectively, with an average 7 conformer exchanges. For unilateral cases, the mean final lid length of involved eyes was 22.3 mm, comparable to 23.5 mm in normal contralateral eyes. Good outcomes were achieved in 18 orbits (75%); fair outcomes, in 6 (25%) cases. None of the sockets had poor expansion at final follow-up. All cases had good cosmesis with acceptable prosthesis wear at last visit.

CONCLUSIONS

In our patient cohort, good socket expansion was achieved with acrylic conformers alone in congenital anophthalmia and microphthalmia, with acceptable prosthesis wear.

Intraorbital self-inflating hydrogel expander implantation with a modified technique in congenital microphthalmia

PURPOSE

To investigate the long-term outcomes of intraorbital self-inflating hydrogel expander implantation with optic nerve transection in children with congenital microphthalmia.

METHODS

The medical records of unilaterally blind microphthalmic pediatric patients undergoing intraconal hydrogel expander implantation with optic nerve transection were reviewed retrospectively. For each patient, the microphthalmic eye was preserved. The orbital volume and globe volume were measured and analyzed based on computed tomography scans taken preoperatively and 36 months postoperatively. The palpebral length was measured between the medial and lateral canthus at every follow-up. Surgical complications were also recorded.

RESULTS

Twelve patients were included (median age, 44.25 ± 17.5 months). At 36 months postoperatively, the microphthalmic and contralateral orbital volumes increased by 3.07 ± 0.77 ml and 2.03 ± 0.67 ml, respectively. The mean microphthalmic/contralateral ratio (MCR) of the orbital volume increased significantly from 76.60% ± 5.46% to 83.81% ± 5.41% (P < 0.001). The microphthalmic palpebral length increased by 6.17 ± 1.85 mm, whereas the contralateral palpebral length increased by 2.67 ± 1.44 mm. Significant changes were observed in the palpebral length MCR (68.00% ± 4.83% vs 85.07% ± 3.87%; P < 0.001). There was no significant change in the microphthalmic globe volume at 36 months postoperatively (P = 0.215). For the fellow eye, the globe volume increased significantly by 0.53 ± 0.34 ml (P < 0.001). During the follow-up period, 2 patients developed a sunken prosthesis. One patient had difficulty opening the eye after wearing the conformer. There were no cases of expander rejection or extrusion.

CONCLUSIONS

In this small cohort of patients with congenital microphthalmia, intraorbital self-expanding hydrogel expander implantation with optic nerve transection led to excellent osseous and eyelid growth throughout the 36-month follow-up period.

Orbital Volume and Axial Length Development in Individuals Ages 12 to 60 Years With Congenital Microphthalmia: A Retrospective Cohort Study

OBJECTIVE

To analyze the stimulating effect of axial length development on orbital volume development in patients (ages 12-60 years) with congenital microphthalmia.

METHODS

This retrospective cohort study included 43 patients (86 eyes) with congenital microphthalmia. Three-dimensional images of the orbit were generated from past computed tomography scans, and digital orbital volume and axial length measurements were taken. The patients were divided into four age groups for analyses. Paired t tests and one-way analysis of variance tests were used to compare orbital volume and axial length between the affected and unaffected eyes. Pearson correlation analyses and scatter plots were used to investigate the correlations between age, orbital volume, and axial length in the affected and unaffected eyes. Linear regression analysis was used to determine the association between orbital volume and axial length.

RESULTS

The mean orbital volume in the affected and unaffected eyes was 17.08 ± 2.88 and 20.80 ± 2.55 cm3, respectively. The mean axis length in the affected and the unaffected groups was 12.73 ± 3.54 and 23.84 ± 1.43 mm, respectively. Significant differences were observed among orbital (t = 13.538, P < 0.001) volume and axial length (t = 21.339, P < 0.001) in the affected and the unaffected groups. There were no significant differences in affected orbital volume (F = 0.527, P > 0.05), unaffected orbital volume (F = 1.628, P > 0.05), affected axial length (F = 0.946, P > 0.05), and unaffected axial length (F = 2.217, P > 0.05) among the four age groups. According to the Pearson correlations, there were no significant correlations between age and affected volume, unaffected volume, affected axis, and unaffected axis (r = 0.095, 0.097, 0.084, and 0.022, respectively; all P > 0.05). Orbital volume was moderately correlated with axial length in the affected and unaffected groups (r = 0.470 and 0.410, respectively; both P < 0.01). Linear regression analysis revealed that a 1 mm change in axis length was associated with a 0.38 cm3 and 0.73 cm3 change in orbital volume in the affected and unaffected groups, respectively.

CONCLUSIONS

In individuals ages 12 to 60 years old with congenital microphthalmia, the effect of axis length on the orbital volume growth of the affected eye is only half that of the unaffected eye. The eyeball, orbital tissue, and craniofacial development all play an important role in the growth of orbital volume.

A Finite Element Analysis Model is Suitable for Biomechanical Analysis of Orbital Development

ABSTRACT

The authors investigated orbital bone development in congenital microphthalmia (CM) using a three-dimensional finite element analysis model, after the orbital dimension deficiency was improved with a self-inflating hydrogel expander implant.Data of a 2-year-old male CM patient were examined. The orbital structure, eyeball, eye muscles, and self-inflating hydrogel expander were constructed according to computed tomography examination data. The effects of self-expanding spherical hydrogel at various locations in the muscle cone on orbital bone development were examined using 3-mL self-expanding expanders placed at shallow (model 1: 2 mm depth) and deep (model 2: 8 mm depth) muscle cone positions. This model simulated the hydrogel expansion process; the orbital bone biomechanics and radial displacement nephograms were obtained when the hydrogel volume increased 3, 5, 7, and 9 times and analyzed.The orbital bone biomechanics were concentrated at the medial orbital wall center, gradually spreading to the whole orbital wall. Biomechanics and radial displacement of the inferior temporal and lateral distal orbital wall region were the most significant, and were more significant in model 1 than in model 2.Finite element analysis is suitable for the biomechanical analysis of orbital development in CM. The shallow position inside CM patients' muscle cone is the optimal site for hydrogel implantation.

Three-dimensional periorbital asymmetry assessment of congenital microphthalmia children with a structured light 3D scanning system

Congenital microphthalmia is a rare phenotype characterized by eye growth retardation. Due to the lack of eyeball stimulation, children suffering from congenital microphthalmia always have bony orbital maldevelopment, which leads to facial asymmetry. In the present study, a structured light 3D scanning system was used as a novel method to measure the three-dimensional periorbital asymmetry in children with congenital microphthalmia. Children with unilateral congenital microphthalmia of 0-6 years old were enrolled in the present study. All participants underwent an ultrasound scan to measure the axial length, and accepted the structured light 3D scanning system for their periorbital appearance. The degree of periorbital asymmetry was evaluated using 17 facial landmarks within a three-dimensional cartesian coordinate system (the X-axis represented the horizontal direction, the Y-axis represented the vertical direction, and the Z-axis represented the sagittal direction). Paired student t-test and ANOVA were used in the present study. A three-dimensional periorbital topography was also established to further illustrate the periorbital asymmetry. A total of 67 children were recruited, which included 31 boys and 34 girls. The axial length on the affected side (12.28 ± 3.35 mm) was generally smaller than that on the unaffected side (20.54 ± 1.65 mm, P < 0.001). When grouped by age, the periorbital asymmetry mainly manifested in the Y-axis and Z-axis directions. The unaffected side had a higher orbitale superior (5.09 ± 0.35 vs. 3.02 ± 0.30, P < 0.001) and a lower orbitale inferior (-19.52 ± 0.51 vs. -16.90 ± 0.53, P < 0.001) in 0-1 year old group. Same performances were also found in the 1-3 and 3-6 age groups. When grouped according to the proportion of axial length on the bilateral sides, seven of the 12 Y-values and all 12 Z-values had statistical differences. The structured Light 3D scanning system may serve as a beneficial complementary tool for computed tomography, in order to better understand the periorbital deformities caused by congenital microphthalmia.

Prenatal diagnosis of bilateral congenital microphthalmia in two fetuses from the same parents

Congenital microphthalmia (CM) is a rare anomaly of the fetal orbit, results from developmental defects of the primary optic vesicle, and is characterized by a reduced eyeball volume and axial diameter. Fetal CM cases have rarely been reported. Herein, we present a case of two fetuses with bilateral CM from the same parents, diagnosed using ultrasonography (US) and magnetic resonance imaging (MRI). We found that the antepartum US and MRI measurements were smaller than the postpartum ones. Genetic testing of the parents and fetuses revealed that GL12 gene mutation may be associated with CM.

Comparative Effectiveness of Different Interventions of Perivascular Hyaluronidase

BACKGROUND

Soft-tissue necrosis caused by vascular compromise is a frequent and troublesome complication of hyaluronic acid filler injection. Hyaluronidase has been proposed as a treatment for this condition. This study aimed to determine the effective dose and administration interval of hyaluronidase injection in a skin necrosis animal model.

METHODS

New Zealand rabbits were used to simulate the hyaluronic acid-associated vascular occlusion model. Hyaluronic acid filler (0.1 ml) was injected into the central auricular artery to create an occlusion. Three rabbit auricular flaps were injected with 500 IU of hyaluronidase once (group A) and three flaps each were injected at 15-minute intervals with 250 IU of hyaluronidase twice (group B), 125 IU of hyaluronidase four times (group C), 100 IU of hyaluronidase five times (group D), and 75 IU of hyaluronidase seven times (group E), all at 24 hours after occlusion. No intervention was administered after occlusion in the control group. Flap fluorescence angiography was performed immediately after hyaluronidase injection and on postoperative days 2, 4, and 7. Flap necrotic areas were analyzed.

RESULTS

All control and experimental flaps demonstrated total occlusion after hyaluronic acid injection. The average total survival rate (positive area/total area ×100 percent) of control flaps was 37.61 percent. For experimental groups, the average total survival rates were 74.83 percent, 81.49 percent, 88.26 percent, 56.48 percent, and 60.69 percent in groups A through E, respectively.

CONCLUSION

A better prognosis can be obtained by administering repeated doses rather than a single high dose of hyaluronidase.

Orbital floor symmetry after maxillectomy and orbital floor reconstruction with individual titanium mesh using computer-assisted navigation

PURPOSE

The present study aimed to evaluate the symmetry of the orbital floor after maxillectomy and orbital floor reconstruction with individual titanium mesh using a computer-assisted navigation system.

PATIENTS AND METHODS

Nineteen patients who underwent orbital floor reconstruction with individual titanium mesh were included in this study. Postoperative computed tomography scans recorded after three-dimensional (3D) reconstruction were used to evaluate the symmetry of the orbital floor, including orbital floor height, orbital floor eminence, globe projection, orbital volume, and surface deviation.

RESULTS

The average orbital floor height of the reconstructed and the unaffected side was 37.7 ± 2.3 and 37.8 ± 2.7 mm, respectively (P = .47). The average orbital floor eminence of the reconstructed and the unaffected side was 40.1 ± 5.5 and 39.6 ± 5.3 mm, respectively (P = .17). The average globe projection of the reconstructed and the unaffected side was 15.5 ± 3.2 and 15.3 ± 3.0 mm, respectively (P = .27). The average orbital volume of the reconstructed and the unaffected side was 25.9 ± 4.4 and 26.3 ± 4.4 cm³, respectively (P = .29). Repeatability between the reconstructed and the unaffected side was 88.3% ± 2.6% at within 1 mm and 98.6% ± 0.9% at within 2 mm. The average of maximum deviation was 2.4 ± 0.2 mm.

CONCLUSION

Individual titanium mesh is one of the best techniques for orbital floor reconstruction, as it can be placed precisely and helps achieve desirable esthetic outcomes through virtual surgical planning and using a computer-assisted navigation system.

Reconstruction strategy in isolated complete Cryptophthalmos: a case series

Background

The present study sought to introduce clinical characteristics and stepwise surgical strategies of isolated complete cryptophthalmos, a rare, congenital ocular anomaly.

Case presentation

Retrospective, noncomparative, clinical study. Six patients with isolated complete cryptophthalmos were diagnosed at the Beijing Tongren Hospital between 2010 to 2018. The presentation age of patients ranged from 1 month to 68 years. This study includes two males and four females, and involvement was noted to be bilateral in two cases and unilateral in four cases. According to orbital CT scan and ocular CDI results, two patients were combined with ocular cyst. Reconstruction surgeries were performed in three patients, involving the eyeball enucleation, creation of fornix, eyelid reconstruction with skin flaps/amniotic membrane, and implantation of prosthesis. Besides, implantation of hydroxyapatite was performed in one pediatric patient to promote orbit development. Good outcomes in terms of cosmetic satisfaction were achieved in all patients during follow-up.

Conclusions

Surgical intervention could only improve the cosmetic appearance in isolated complete cryptophthalmos. The surgical strategies may be planned to use three-stage approaches described in this study. Meanwhile, orbital development must be taken into consideration in pediatric cases.

Management of congenital microphthalmos and anophthalmos with orbital cyst

PURPOSE

To study the effects of an individualized treatment approach to children with congenital microphthalmos and anophthalmos.

METHODS

Patients with congenital microphthalmos or anopthalmos with orbital cysts who were referred to Beijing Tongren Hospital between July 2009 and July 2017 were included in this retrospective case series study. For patients ≤6 years of age, the cyst was retained to promote orbital development unless a prosthesis could not be fitted at all or disproportionate orbital growth was detected. Hydrogel orbit expanders were implanted initially if orbital volume was poor. For patients >6 years of age, the cyst was removed if it caused cosmetic problems or unsatisfactory prosthesis fitting. Eyelid procedures were performed after puberty to improve appearance.

RESULTS

The study included 26 orbits of 24 patients. Of the 14 patients ≤6 years, 3 underwent cyst excision, 8 were treated with conformers only, and 3 had hydrogel orbit expander implantation initially. Of the 10 patients >6 years, 1 had the cyst removed, 5 had eyelid surgeries without removing the cyst, 3 wore an artificial eye without any surgery, and 1 used no prosthesis. During the follow-up period (range, 6 months to 8 years), 23 patients had a good cosmetic outcome and were eventually able to retain an ocular prosthesis; 1 patient could not wear prostheses but refused further treatment. No procedure-related complications were noted.

CONCLUSIONS

The individualized treatment of congenital microphthalmos and anophthalmos with orbital cysts depends on the patient's age at presentation, the growth pattern of the cyst, and the volume of the affected orbit.

Biphasic growth of orbital volume in Chinese children

Objective

The aim of this study was to map out the developmental curve of the orbital volume of Chinese children aged 1–15 years.

Methods

CT scanning was performed on 109 children and the orbital volume, interlateral orbital rim distance (IORD), and extent of exophthalmos were measured on the CT images and plotted against age.

Results

The development of the orbit structure followed a biphasic pattern. The first growth phase was before 3 years and the second growth phase was between 7 years and 12 years of age. The growth speed in the first phase was about 3 times that of the second one (first vs second phase: 2.28 cm³/year vs 0.67 cm³/year for orbital volume, 5.01 mm/year vs 1.57 mm/year for IORD, 1.29 mm/year vs 0.42 mm/year for the exophthalmos). During development, there was no significant difference between the left and right orbits. There was no significant difference between boys and girls before 12 years of age. However, after 12 years of age, boys had significantly larger orbital volumes (22.16±2.28 cm³/year vs 18.57±1.16 cm³/year, p<0.001) and a greater IORD (96.29±3.18 mm/year vs 91.00±4.54 mm/year, p<0.001) than girls.

Conclusions

In Chinese children, the development of orbital volume follows a biphasic pattern and a sex difference becomes significant after the age of 12 years.