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05:19
Automated Compression Testing of the Ocular Lens
Published on: April 5, 2024
Shear modulus data for the human lens determined from a spinning lens test
G S Wilde1, H J Burd, S J Judge
1Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
Experimental Eye Research
|February 14, 2012
Summary
This study measured the shear modulus of human eye lenses to model accommodation. Lens stiffness increases with age, with the nucleus becoming stiffer than the cortex around age 45.
Area of Science:
- Ophthalmology
- Biomechanical Engineering
- Materials Science
Background:
- Accurate computational models of the eye's accommodation process require precise material properties of the human lens.
- Previous studies have yielded inconsistent data on lens biomechanics, necessitating further experimental investigation.
Purpose of the Study:
- To experimentally determine the shear modulus of human eye lenses across a range of ages.
- To provide data for developing computational models of the eye's accommodation process.
- To investigate age-related changes in lens mechanical properties.
Main Methods:
- Mechanical testing of donated human eye bank lenses using a spinning test rig to induce deformation.
- Finite element inverse analysis to infer shear modulus from observed deformations.
- Testing of 29 lenses from individuals aged 12 to 58 years, with post-mortem times ranging from 47 to 110 hours.
Main Results:
- For younger lenses, the cortex is stiffer than the nucleus.
- Both nuclear and cortical shear moduli increase with age.
- The nucleus becomes stiffer than the cortex from approximately 45 years of age onwards due to a more rapid increase in nuclear stiffness.
Conclusions:
- The study provides crucial shear modulus data for human lenses, essential for refining accommodation models.
- Age-related changes in lens stiffness, particularly the shift in relative stiffness between nucleus and cortex, are quantified.
- The developed 'age-stiffness' models are suitable for integration into finite element models of accommodation.
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