Changes in angle of optic nerve and angle of ocular orbit with increasing age in Japanese children

The influence of orbital architecture on strabismus in craniosynostosis

PURPOSE

To better characterize the correlation of bony orbital dysmorphology with strabismus in craniosynostosis.

METHODS

The medical records of patients with craniosynostosis with and without strabismus seen at Rady Children's Hospital (San Diego, CA) from March 2020 to January 2022 were reviewed retrospectively in this masked, case-control study. Computed tomography scans of the orbits were analyzed to obtain dimensions of the orbital entrance and orbital cone. Primary outcome was correlation of strabismus with orbital measurements.

RESULTS

A total of 30 orbits from 15 patients with strabismus and 15 controls were included. Craniofacial disorders included in the study were nonsyndromic craniosynostosis (63%), Crouzon syndrome (13%), Apert syndrome (13%), and Pfeiffer syndrome (10%). Orbital index (height:width ratio) (P = 0.01) and medial orbital wall angle (P = 0.04) were found to differ significantly between the strabismus and control groups.

CONCLUSIONS

In our small cohort, bony orbital dimensions, including the ratio of orbital height to width and bowing of the medial orbital wall, were associated with strabismus in craniosynostosis.

Relationship between strabismus associated with Angelman syndrome and orbital anomaly

PURPOSE

To investigate the relationship between the details of strabismus and orbital abnormalities determined by ocular motility tests and orbital imaging examinations in 9 cases with Angelman syndrome (AS).

STUDY DESIGN

A retrospective, clinical report.

METHODS

The 9 AS cases (mean age at initial visit: 4.6 ± 8.0 years) were confirmed by genetic diagnosis of the chromosome 15q11-13 region. In all cases, axial imaging of the orbit in the transverse plane of the horizontal extraocular muscles was obtained. The opening angle between both lateral walls of the orbit (greater wing of sphenoid) was measured as the biorbital angle, and compared with the 95% confidence interval of the orbital angle in normal children.

RESULTS

All cases had exotropia with means of the distance and near of angle 32.2 prism diopters (Δ) ± 9.7Δ and 32.8Δ ± 8.3Δ. The mean of the biorbital angle was 107.7° ± 7.6°, greater than the biorbital angle of 94.3° ± 5.1° previously reported in 129 normal children (P < 0.0001, t-test). Except for one biorbital angle of 93° in the 25-year-old patient, all the biorbital angles in the 8 children were larger than the upper 95% confidence interval in normal children. Astigmatic and hyperopic ametropic amblyopia were detected in 3 cases and 1 case, respectively.

CONCLUSIONS

The frequency of exotropia in AS is higher than previously reported, with our results strongly suggesting that the enlarged biorbital angle is related to the pathogenesis of exotropia in AS.

Abnormal biorbital angle in children with infantile exotropia

PURPOSE

The causative factors of infantile exotropia are unknown. The purpose of this study was to investigate the relationships between the biorbital angle and the pathogenesis of infantile exotropia.

STUDY DESIGN

Retrospective.

METHODS

Of all patients diagnosed as infantile exotropia with onset prior to 12 months of age between 2010 and 2017, 31 patients without any neurological disorders or developmental delay were identified. The angle between both lateral walls of the orbit, defined as the biorbital angle, was measured in the horizontal plane at the optic nerve and where the horizontal extraocular muscles appeared on axial magnetic resonance imaging (MRI) or computed tomography (CT) of the orbit. These patients' data were compared with those of 129 ophthalmologically normal children. All subjects of this study were Japanese.

RESULTS

The mean biorbital angle was significantly larger in patients with infantile exotropia than in the normal children (106.6 ± 5.7° vs 94.2 ± 5.1°, p < 0.001). Of the patients with infantile exotropia, 21 (68%) had an angle outside the 95% confidence interval calculated in normal children. All cases were divided into a constant (15 cases) and intermittent (16 cases) group; there was no significant difference between them in the mean biorbital angles (107.9 ± 5.6° vs 105.4 ± 5.8°, p = 0.224). No correlations were identified between the biorbital angle and the angle of exodeviation, either distant or near.

CONCLUSIONS

Children with infantile exotropia have a larger biorbital angle. This anatomical abnormality may be an associate factor of infantile exotropia.

Developmental change of the biorbital angle in normal Japanese infants

Purpose

To investigate postnatal changes in the biorbital angle in normal Japanese children.

Subjects and methods

Axial imaging of the orbit in the transverse plane of the horizontal extraocular muscles was obtained in 129 ophthalmologically healthy infants (age ranging from a few months to 11 years). The opening angle between both lateral walls of the orbit was defined as the biorbital angle.

Results

The mean biorbital angle in 11 infants less than a year of age was 105.0°±6.0°. The mean biorbital angles for each of the subsequent age groups were 97.7°±3.1°, 96.2°±4.0°, 96.3°±4.1°, 92.8°±3.8°, 92.3°±2.3°, 93.1°±2.8°, 91.5°±3.9°, 91.9°±2.3°, 91.4°±2.3°, and 90.9°±3.1°. The mean biorbital angle in infants less than a year old was significantly larger than those found in the groups of infants older than 1 year (P<0.01, Newman-Keuls test).

Conclusion

The biorbital angle in infants less than a year old was larger than that found in infants older than 1 year, with this larger biorbital angle potentially the causative factor of the observed exotropia seen in 70%-80% of newborns gradually disappearing in most cases by 2-4 months of age.

What is the Main Potential Factor Influencing Ocular Protrusion?

Background

The aim of the present study was to establish the normal-range orbital parameters and to explore the relationships between ocular protrusion and various orbital morphological factors.

Material/Methods

A retrospective, non-comparative case series was conducted from January 2014 to December 2015. We recruited 56 subjects (112 orbits), including 27 males (21 to 87 years of age) and 29 females (22 to 88 years of age) in this study. Nine length measurements, 2 angle measurements, and 2 volume measurements of various aspects of the orbit were obtained using Mimics v18.0 software. The data were collected manually using a 3D measurement technique. Statistical analyses using t tests and Pearson’s correlation analyses were performed to evaluate the differences and relationships between the parameters, respectively.

Results

Ocular protrusion in both sexes was closely related to the following values: orbital soft tissue volume (OSTV) (males: r=0.61, p<0.001; females: r=0.39, p=0.003), orbital soft tissue volume/bony orbital volume (OSTV/BOV) (males: r=0.90, p<0.001; females: r=0.87, p<0.001), orbital width (males: r=0.40, p=0.003; females: r=0.53, p<0.001), orbital height (males: r=0.29, p=0.038; females: r=0.45, p<0.001), and globe diameter (males: r=0.52, p<0.001; females: r=0.48, p<0.001). No differences were found between the right and left orbits.

Conclusions

The study provides insight into the potential factors that influence ocular protrusion, which include the OSTV/BOV ratio, the shape of the orbital aperture, and the ocular axial length. The results of orbital surgery can be made more predictable by accounting for these 3 factors. The database and regression formula might provide support for surgical planning in the future.