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. 2022 Jul;42(7):1997-2005.
doi: 10.1007/s10792-021-02157-6. Epub 2022 Jun 4.

Finite element method for estimation of applanation force and to study the influence of intraocular pressure of eye on tonometry

R B Bharathi  1 , Rakshath G Poojary  2 , Gopalakrishna K Prabhu  3 , Ramesh S Ve  4
Affiliations

Finite element method for estimation of applanation force and to study the influence of intraocular pressure of eye on tonometry

R B Bharathi et al. Int Ophthalmol. 2022 Jul.

Abstract

Purpose: Discover the associations of force of applanation on the eye with the plunging depth of the cornea and quantify them. The results will be utilized as the feedback parameter in the new prototype development of eye care instruments as additional force may damage the internal structure of the eye or may result in erroneous output.

Method: A finite element-based eye model is designed utilizing the actual dimensions of the human eye. A standardized tonometer is designed and the simulation is carried out at predetermined deformation of the cornea to find the force of applanation on the cornea during tonometry. Adding on, the influence of IOP during tonometry is analyzed for a range of plunging depths of the cornea.

Results: The graphical results inferred the linear relation between the force of applanation with the deformation of the cornea and the results are quantified. The resulting deformation and stress plot of FEM based simulation approach is analyzed and observations regarding deformations and stress are made.

Conclusion: The human eye is successfully developed and also computed force on the cornea during tonometry is validated. The inference drawn from the deformation plot and stress plot is that the junction of cornea-sclera along with cornea-tonometer periphery undergo maximum deformation and experiences the highest stress compared to other areas of the eye while during tonometry.

Keywords: Biomechanical simulation; Finite element analysis; Glaucoma; IOP; Tonometry.

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Conflict of interest statement

All authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Key point sketches (dimensions in mm)
Fig. 2
Fig. 2
Deformation of cornea under tonometry for varying displacement of tonometer, a 0.3 mm, b 0.4 mm, c 0.5 mm, d 0.6 mm, e 0.7 mm, f 0.7 mm isometric view with tonometer with 20 mmHg of IOP
Fig. 3
Fig. 3
Stress distribution (MegaPascal) of eye under tonometry for 20 mmHg IOP for displacement of a 0.3 mm, b 0.4 mm, c 0.5 mm, d 0.6 mm, e 0.7 mm, f 0.6 mm cut section view
Plot 1
Plot 1
Force (Newton) exerted on cornea by tonometer for varying deformation of cornea (mm)
Fig. 4
Fig. 4
Validation plot
See this image and copyright information in PMC

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