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Updated: Jun 4, 2025
05:14
Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher
Published on: February 23, 2018
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Ciliary muscle traction during accommodation is able to induce optic nerve head deformation
Tingting Liu1,2, Kehao Wang1,3, Ya Xing Wang4
1Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China.
Eye (London, England)
|January 4, 2025
Summary
Ciliary muscle traction during accommodation causes significant optic nerve head deformation. Stiffer ocular tissues amplify this effect, increasing lamina cribrosa strain.
Area of Science:
- Ophthalmology
- Biomechanics
- Medical Imaging
Background:
- Accommodation involves ciliary muscle contraction, which can influence intraocular structures.
- Optic nerve head (ONH) deformation is a critical factor in glaucoma pathogenesis.
- Understanding accommodation's effect on the ONH is crucial for diagnosing and managing optic neuropathies.
Purpose of the Study:
- To investigate the impact of ciliary muscle traction on ONH deformation during accommodation using finite element (FE) modeling and optical coherence tomography (OCT) imaging.
- To analyze how variations in ocular tissue stiffness affect accommodation-induced ONH strains.
Main Methods:
- A FE model simulating ciliary muscle traction during accommodation was developed.
- The stiffness of the sclera, choroid, Bruch's membrane (BM), prelaminar neural tissue, and lamina cribrosa (LC) were parametrically varied.
- In vivo OCT imaging of 20 subjects' ONHs was performed during 0D and 6D accommodation to validate the model and measure ONH strains, choroidal thickness, and BMO changes.
Main Results:
- FE modeling demonstrated that ciliary muscle pulling force transmits to the ONH via the choroid and BM.
- Accommodation-induced LC strain (0.057 ± 0.033) was significantly higher than at rest (0.023 ± 0.014).
- Increased choroidal and BM stiffness led to greater accommodation-induced LC strain, comparable to that from a 45 mmHg IOP elevation.
Conclusions:
- Ciliary muscle traction during accommodation induces substantial ONH deformation.
- Stiffer choroid and BM tissues enhance the transmission of traction forces to the ONH, increasing LC strain.
- These findings highlight a potential biomechanical link between accommodation and optic nerve health.
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