A study for lens capsule tearing during capsulotomy by finite element simulation

Area of Science:

• Ophthalmic surgery
• Biomechanical engineering
• Computational modeling

Background:

• Capsulotomy involves applying force to the anterior lens capsule, a critical factor influencing tear dynamics and surgical outcomes.
• Understanding the precise forces involved in capsule tearing is essential for optimizing surgical techniques and preventing complications.

Purpose of the Study:

• To investigate the tear force during capsulotomy using a computational approach.
• To analyze how different tearing conditions affect the magnitude and characteristics of the tear force.

Main Methods:

• A 3D finite element (FE) model of the human lens was created, incorporating anterior and posterior capsules, cortex, and nucleus.
• Crack propagation was modeled using a distortion energy failure criterion and a bilinear interface law.
• Simulations were validated against experimental capsulorhexis in porcine eyes using force-sensing forceps.

Main Results:

• The FE model demonstrated good agreement with experimental data, with small mean force differences (3.10 ± 2.24 mN and 2.14 ± 1.73 mN).
• Minimum mean tear force was observed at specific tear directions (θ₁ = 0°, θ₂ = 30°).
• An appropriate capsulorhexis diameter was found to reduce tear force, while tear velocity showed no significant impact.

Conclusions:

• The developed FE model is a viable tool for simulating lens capsule tearing.
• This model facilitates the theoretical study of tear mechanisms in capsulotomy.
• Findings provide insights into optimizing surgical parameters for safer and more effective capsulotomy.