Finite element analysis and in vitro simulation experiments on ophthalmic trocar needles

Area of Science:

• Ophthalmic surgery
• Biomechanical engineering
• Medical device design

Background:

• Ophthalmic trocar systems are crucial for vitreous cavity access in complex eye surgeries.
• Optimizing trocar needle design may reduce surgical trauma and complications.

Purpose of the Study:

• To investigate the impact of ophthalmic trocar needle design parameters on penetration force and stress distribution.
• To provide a scientific basis for the design of improved ophthalmic trocar systems.

Main Methods:

• Combined in vitro simulation tests with finite element analysis.
• Evaluated four trocar needles varying in outer diameter (23G, 25G), bevel length, and tip surface area.
• Performed penetration force tests and measurements.

Main Results:

• Smaller diameter (25G) needles showed significantly lower penetration force (14.62%).
• Needles with smaller tip surface area and longer bevels exhibited reduced penetration force.
• Finite element analysis revealed needle tip geometry dictates initial stress concentration, while shaft properties influence overall stress distribution.

Conclusions:

• A multi-stage tapering needle with a truncated apex and appropriate bevel length enhances tip strength and cutting efficiency.
• Optimized trocar needle design can improve penetration efficiency and reduce surgical trauma.
• Findings support the development of more precise and minimally invasive ophthalmic surgical instruments.