Purpose To assess gaze evoked deformations of the optic nerve head (ONH) in thyroid eye disease (TED), using computational modelling and optical coherence tomography (OCT).
Methods Multiple finite element models were constructed: one model of a healthy eye, and two models mimicking effects of TED; one with proptosis and another with extraocular tissue stiffening. Two additional hypothetical models had extraocular tissue softening or no extraocular tissue at all. Horizontal eye movements were simulated in these models. OCT images of the ONH of 10 healthy volunteers and 1 patient with TED were taken in primary gaze. Additional images were recorded in the same subjects performing eye movements in adduction and abduction. The resulting ONH deformation in the models and human subjects was measured by recording the ‘tilt angle’ (relative antero-posterior deformation of the Bruch’s membrane opening).
Results In our computational models the eyes with proptosis and stiffer extraocular tissue had greater gaze-evoked deformations than the healthy eye model, while the models with softer or no extraocular tissue had lesser deformations, in both adduction and abduction. In healthy subjects, the mean tilt angle was 1.46°±0.25 in adduction and −0.42°±0.12 in abduction. The tilt angle measured in the subject with TED was 5.37° in adduction and −2.21° in abduction.
Conclusion Computational modelling and experimental observation suggest that TED can cause increased gaze-evoked deformations of the ONH.
- optic nerve
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Presented at An abstract of this article was previously presented at the Association for Research in Vision and Ophthalmology 2019 annual meeting.
Contributors Design of study: LKF, XW, MJAG. Conduct of study: XW, TAT, H-WC, DM. Collection and management of data: LKF, XW, TAT. Analysis and interpretation of data: LKF, XW, MJAG. Preparation of manuscript: LKF, MJAG. Review or approval of manuscript: LKF, XW, TAT, H-WC, DM, MJAG.
Funding Singapore Ministry of Education, Academic Research Funds Tier 2, R-397-000-308-112 (MJAG); National Natural Science Foundation of China, 12002025 (XW); NGS Scholarship (LKF).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All subjects gave written informed consent. The study adhered to the tenets of the Declaration of Helsinki and was approved by the institutional review board of the Singapore National Eye Centre.
Data availability statement No data are available.
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