Orbital Growth is Associated with Eyeball Size: A Study Using CT-based Three-dimensional Techniques.

AIM OF THE STUDY: This study was aimed to investigate the growth patterns and the relationship of the eyeball and the orbit using computed tomography (CT)-based three-dimensional (3D) techniques. MATERIALS AND METHODS: A total of 175 Chinese patients who had undergone craniofacial or orbital CT scans were enrolled. This study only included data from the unaffected eye and orbit. Images were processed using 3D reconstruction to obtain the eyeball and the orbit parameters. RESULTS: In early postnatal years, the sizes of eyeball and orbit increased significantly with age (p < 0.001) and reached a turning point at a critical age (8.967 and 12.800 years for the eyeball and orbit volume, respectively). The orbital index and orbital depth index, showing the shape of the orbital aperture and walls, decreased significantly with age (p < 0.001). In all ages, the orbit size was correlated with eyeball size (p < 0.001). The eye-orbit index, equivalent to the ratio of eye volume to orbital volume, declined steadily with age (p < 0.001). CONCLUSIONS: The eyeball and orbit developed rapidly in early postnatal years, and then matured at a critical age. The eyeball size significantly contributed to the orbital growth; this contribution may be reduced as the eye-orbit index decreased with age. To the best of our knowledge, this is the first report on the growth and interrelation of the eyeball and the orbit using CT-based 3D techniques.

Spontaneous eye movements during eyes-open rest reduce resting-state-network modularity by increasing visual-sensorimotor connectivity.

During wakeful rest, individuals make small eye movements during fixation. We examined how these endogenously driven oculomotor patterns impact topography and topology of functional brain networks. We used a dataset consisting of eyes-open resting-state (RS) fMRI data with simultaneous eye tracking. The eye-tracking data indicated minor movements during rest, which correlated modestly with RS BOLD data. However, eye-tracking data correlated well with echo-planar imaging time series sampled from the area of the eye-orbit (EO-EPI), which is a signal previously used to identify eye movements during exogenous saccades and movie viewing. Further analyses showed that EO-EPI data were correlated with activity in an extensive motor and sensorimotor network, including components of the dorsal attention network and the frontal eye fields. Partialling out variance related to EO-EPI from RS data reduced connectivity, primarily between sensorimotor and visual areas. It also produced networks with higher modularity, lower mean connectivity strength, and lower mean clustering coefficient. Our results highlight new aspects of endogenous eye movement control during wakeful rest. They show that oculomotor-related contributions form an important component of RS network topology, and that those should be considered in interpreting differences in network structure between populations or as a function of different experimental conditions.

Prediction of muscle activation for an eye movement with finite element modeling.

In this paper, a 3D finite element (FE) modeling is employed in order to predict extraocular muscles' activation and investigate force coordination in various motions of the eye orbit. A continuum constitutive hyperelastic model is employed for material description in dynamic modeling of the extraocular muscles (EOMs). Two significant features of this model are accurate mass modeling with FE method and stimulating EOMs for motion through muscle activation parameter. In order to validate the eye model, a forward dynamics simulation of the eye motion is carried out by variation of the muscle activation. Furthermore, to realize muscle activation prediction in various eye motions, two different tracking-based inverse controllers are proposed. The performance of these two inverse controllers is investigated according to their resulted muscle force magnitude and muscle force coordination. The simulation results are compared with the available experimental data and the well-known existing neurological laws. The comparison authenticates both the validation and the prediction results.

A Study of Bilateral Asymmetry Pattern in the Eye Orbit and Nose of the Joseon Dynasty Skeletal Group Using Geometric Morphometrics / 체질인류학회지

In this study, the pattern of bilateral asymmetry in the eye orbit and nose of the Joseon Dynasty skeletal group was analyzed using geometric morphometrics. For this, 38 adult males and 38 adult females from the Joseon Dynasty skeletal group belonging to the 15(th) to early 20(th) centuries were examined. For geometric morphometric analysis, Procrustes superimposition was performed on 10 landmarks in both eye orbits and 7 nasal landmarks. The data were analyzed by multivariate analysis of variance with partial least square scores. In results, the lateral landmarks had more impact on the bilateral asymmetry in the eye orbit and nose than the center landmarks. The eye orbit and nose on the right side of the face seemed bigger than those of the left side, while the direction of asymmetry in the eye orbit and nose was different. The correlation between asymmetry patterns in the eye orbit and nose were statistically significant (p<0.01). The results of this study will be useful for examining causes of bilateral asymmetry in the eye orbits and noses of the Korean population.

How can bioactive glasses be useful in ocular surgery?

In the last few decades, the introduction of bioactive glasses (BGs), a special class of bioceramics that are able to bond to living tissues stimulating new tissue growth, has improved both treatment procedures via reconstructive surgery and the quality of life of rehabilitated patients in orthopedics and dentistry. While BGs have been extensively investigated for applications in these two surgical fields, there has been relatively little research on their use in other medical areas. Glass has been used for centuries to produce external refractive lenses and the intraocular implantation of small glass disks to correct visual deficiencies has been documented since the mid 1700s. Moreover, some evidences reported in the recent literature seem to demonstrate that the success of three specific types of ophthalmic devices, that is, synthetic grafts for eye orbit bone repair, orbital implants replacing the whole ocular globe and keratoprostheses (artificial cornea), could significantly benefit by the use of BG. A prospective view as well as a state-of-the-art review on this topic are currently lacking in the literature. The present article aims to give a comprehensive picture of the BG-based implants that have been developed in the context of ocular surgery; the strengths and shortcomings of the existing devices are outlined in order to provide useful stimuli for future research. Promising research directions are also proposed, emphasizing the added values that BGs could carry in ophthalmology in the light of recent findings in tissue engineering and regenerative medicine.