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Gaze-evoked deformations of the optic nerve head in thyroid eye disease
  1. Liam K Fisher1,2,
  2. Xiaofei Wang2,3,
  3. Tin A Tun2,4,
  4. Hsi-Wei Chung4,
  5. Dan Milea4,5,
  6. Michael J A Girard2,4,5
  1. 1NUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore
  2. 2Ophthalmic Engineering & Innovation Laboratory, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
  3. 3Biological Science and Medical Engineering, Beihang University, Beijing, China
  4. 4Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
  5. 5Duke-NUS Medical School, Singapore
  1. Correspondence to Dr Michael J A Girard, Ophthalmic Engineering & Innovation Laboratory, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore; mgirard{at}ophthalmic.engineering

Abstract

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
  • orbit

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Footnotes

  • 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.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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