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Updated: Jul 3, 2026
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Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher
Published on: February 23, 2018
Constant volume of the human lens and decrease in surface area of the capsular bag during accommodation: an MRI and
Erik A Hermans1, Petra J W Pouwels, Michiel Dubbelman
1Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands. ea.hermans@vumc.nl
Investigative Ophthalmology & Visual Science
|August 5, 2008
Summary
The human lens maintains a constant volume during accommodation, indicating its material is incompressible and deforms elastically. The capsular bag also deforms elastically, as shown by changes in surface area.
Area of Science:
- Ophthalmology
- Biophysics
- Medical Imaging
Background:
- Understanding the biomechanical properties of the human lens during accommodation is crucial for explaining visual function.
- Previous theories proposed different mechanisms for lens shape changes, involving compressibility or elasticity.
Purpose of the Study:
- To investigate whether changes in lens shape during accommodation are due to material compressibility or elasticity.
- To quantify changes in lens surface area and volume during accommodation.
Main Methods:
- Three-dimensional magnetic resonance imaging (3D MRI) was used to capture the complete lens shape in five healthy young adults.
- A parametric model and Canny edge filter were employed to analyze lens cross-sectional shape, area, volume, and surface area changes.
- Corrected Scheimpflug imaging validated the MRI measurements.
Main Results:
- No significant differences were observed between MRI and Scheimpflug imaging for lens curvature and thickness.
- Accommodation led to decreased radii of curvature and equatorial diameter, and increased lens thickness, consistent with the Helmholtz theory.
- Mean cross-sectional area increased, surface area decreased, but lens volume remained constant.
Conclusions:
- The constant lens volume suggests the internal lens material is incompressible and undergoes elastic deformation.
- The observed changes in surface area indicate that the capsular bag also exhibits elastic deformation during accommodation.
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