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Evaluation of Goldmann applanation tonometry using a nonlinear finite element ocular model
Ahmed Elsheikh1, Defu Wang, Aachal Kotecha
1Division of Civil Engineering, Faculty of Engineering, University of Dundee, Dundee, DD1 4HN, UK. a.i.h.elsheikh@dundee.ac.uk
Annals of Biomedical Engineering
|September 29, 2006
Summary
Goldmann applanation tonometry (GAT) measurements of intra-ocular pressure (IOP) can be inaccurate due to variations in corneal properties. This study used finite element analysis to show how corneal thickness and material affect IOP readings.
Area of Science:
- Ophthalmology
- Biomechanical Engineering
- Computational Mechanics
Background:
- Goldmann applanation tonometry (GAT) is the standard for measuring intra-ocular pressure (IOP), crucial for glaucoma diagnosis.
- GAT does not account for individual variations in corneal thickness, curvature, or material properties, potentially causing measurement inaccuracies.
Purpose of the Study:
- To assess the impact of variations in corneal parameters on GAT-derived IOP measurements using numerical analysis.
- To investigate the relationship between corneal biomechanics and IOP measurement accuracy.
Main Methods:
- Finite element method (FEM) was employed to simulate GAT loading conditions.
- Nonlinear, hyper-elastic material properties of corneal tissue were incorporated into the model.
- Clinical data from 532 glaucoma patients were analyzed for comparison.
Main Results:
- Corneal thickness and material properties significantly influence GAT IOP measurements.
- Corneal curvature demonstrated a less pronounced effect on IOP readings.
- FEM analysis accurately modeled corneal behavior under pressure and provided insights into stress and strain distribution.
Conclusions:
- Individual corneal properties, particularly thickness and material characteristics, are critical factors affecting the accuracy of Goldmann applanation tonometry.
- Nonlinear finite element modeling offers a valuable tool for understanding corneal biomechanics and improving IOP measurement accuracy in glaucoma diagnosis.
