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Adduction induces large optic nerve head deformations in subjects with normal-tension glaucoma
  1. Thanadet Chuangsuwanich1,2,
  2. Tin A Tun1,3,
  3. Fabian A Braeu1,4,
  4. Xiaofei Wang5,
  5. Zhi Yun Chin1,
  6. Satish K Panda1,6,
  7. Martin Buist6,
  8. Dan Milea1,3,
  9. Nicholas Strouthidis7,
  10. Shamira Perera1,3,
  11. Monisha Esther Nongpiur1,3,
  12. Tin Aung1,2,3,
  13. Michael J A Girard1,3
  1. 1 Singapore Eye Research Institute, Singapore National Eye Center, Singapore
  2. 2 Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
  3. 3 Duke-NUS Medical School, Singapore
  4. 4 Singapore-MIT Alliance for Research and Technology, Singapore
  5. 5 Beijing Advanced Innovation Center for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
  6. 6 Department of Biomedical Engineering, National University of Singapore, Singapore
  7. 7 National Institute of Health Research, Moorfields Eye Hospital, London, UK
  1. Correspondence to Dr Michael J A Girard, Singapore National Eye Centre, Singapore, 168751, Singapore; mgirard{at}ophthalmic.engineering

Abstract

Purpose To assess intraocular pressure (IOP)-induced and gaze-induced optic nerve head (ONH) strains in subjects with high-tension glaucoma (HTG) and normal-tension glaucoma (NTG).

Design Clinic-based cross-sectional study.

Methods The ONH from one eye of 228 subjects (114 subjects with HTG (pre-treatment IOP≥21 mm Hg) and 114 with NTG (pre-treatment IOP<21 mm Hg)) was imaged with optical coherence tomography (OCT) under the following conditions: (1) OCT primary gaze, (2) 20° adduction from OCT primary gaze, (3) 20° abduction from OCT primary gaze and (4) OCT primary gaze with acute IOP elevation (to approximately 33 mm Hg). We then performed digital volume correlation analysis to quantify IOP-induced and gaze-induced ONH tissue deformations and strains.

Results Across all subjects, adduction generated high effective strain (4.4%±2.3%) in the LC tissue with no significant difference (p>0.05) with those induced by IOP elevation (4.5%±2.4%); while abduction generated significantly lower (p=0.01) effective strain (3.1%±1.9%). The lamina cribrosa (LC) of HTG subjects exhibited significantly higher effective strain than those of NTG subjects under IOP elevation (HTG: 4.6%±1.7% vs NTG: 4.1%±1.5%, p<0.05). Conversely, the LC of NTG subjects exhibited significantly higher effective strain than those of HTG subjects under adduction (NTG: 4.9%±1.9% vs HTG: 4.0%±1.4%, p<0.05).

Conclusion We found that NTG subjects experienced higher strains due to adduction than HTG subjects, while HTG subjects experienced higher strain due to IOP elevation than NTG subjects—and that these differences were most pronounced in the LC tissue.

  • Optic Nerve
  • Glaucoma

Data availability statement

Data are available upon reasonable request. Deidentified patient data (ONH strains) is available upon request.

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Data availability statement

Data are available upon reasonable request. Deidentified patient data (ONH strains) is available upon request.

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Footnotes

  • Contributors The authors confirm contribution to the paper as follows: study conception and design: TC, FAB, T, MJAG, TAT, XW, MB, NS, DM, SP, MEN, SKP; data collection: TC, TAT, ZYC; analysis and interpretation of results: TC, TAT, MJAG; manuscript preparation: TC, MJAG, TAT. MJAG is the guarantor of the manuscript. All authors reviewed the results and approved the final version of the manuscript.

  • Funding This work was supported by (1) the Singapore Ministry of Education, Academic Research Funds, Tier 2 (R-397-000-280-112; R-397-000-308-112), (2) Singapore Ministry of Education, Academic Research Funds, Tier 1 (R-397-000-294-114), (3) the National Medical Research Council (Grant NMRC/STAR/0023/2014), (4) National Natural Science Foundation of China (12002025), (5) Tracking and Reducing Glaucoma Blindness with Emerging Technologies (TARGET, MOH-OFLCG21jun-0003) and (6) the 'Retinal Analytics through Machine learning aiding Physics (RAMP)' project supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Intra-Create Thematic Grant 'Intersection Of Engineering And Health' - NRF2019-THE002-0006 awarded to the Singapore MIT Alliance for Research and Technology (SMART) Centre.

  • Competing interests MJAG is the co-founder of the AI start-up company Abyss Processing Pte Ltd.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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