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While working at Bausch + Lomb, Rob created and presented this work in 2010. No content has been changed from the approved document.

FEA of Prosthetic Lens Insertion During Cataract Surgery Rob Stupplebeen (Bausch + Lomb) Cheryl Liu (Abaqus) Xiaoliang Qin (Abaqus)

Cataracts and basic surgical technique Design overview of a prosthetic lens Design overview of a lens inserter Details of analysis Results Lessons learned Questions

What is a Cataract?

Surgical Technique Corneal incision Removal of crystalline lens (vacuum, irrigation, and ultrasonic) Inserter Intraocular Lens (IOL) Post surgical outcome

Prosthetic Lens Design

Prosthetic Lens Design ISO haptic compression test Compression force Lens vault Optical properties In-vivo

Inserter Design Lunger Tip IOL Loading Area

IOL Compression Ratio Compression ratio C=Area Lens / Area Inserter This design 1.8mm incision, C=2.2 Future design goal 1mm incision, C=3.3

fea-of-prosthetic-lens-insertion-during-cataract-surgery9

IOL Geometry Loading area: rigid, R3D4 Door: rigid, R3D4 Lens: deformable, C3D8R and C3D4 elements Plunger : deformable, C3D8R and C3D4 elements (longer than shown) Tip: deformable, C3D4 elements Top Top door removed right section cut

IOL Analysis Details Step definition Type: Dynamic, Explicit Time period: 1sec Nlgeom: On Mass scaling used during preliminary analyses only Material models Inserter: Linear elastic from vendor data Lens: Neo Hooke fitted from compression data Contact General contact Pressure-Overclosure: Scale Factor Constraints Rigid body Tied between loading area and tip Boundary conditions Rigid bodies and tip given initial velocity (tip velocity suppressed after finite time period End of plunger fixed

Rayleigh damping Rayleigh damping (reduces low frequency oscillations) α (mass proportional) used β (stiffness proportional) not used First natural frequency of the lens was predicted with a separate modal analysis α selected based on this value

IOL Results Force vs. Displacement Test data thin black lines, Model data blue diamonds Filtered model data pink Data noisy requires either a more refined mesh or filtering of data Un-modeled spring causes the force to rise in the test data

IOL FEA Lessons Learned Improved Model Robustness Fillets: Provide a smoother transition for sliding contact Deformable geometry: In place of rigid geometry allows the stiff part to deform slightly reducing the effect of hard corners

IOL FEA Mesh Large deformations occurring in circled area due to plunger loading Lens sectioned to allow brick elements which showed more robustness to large deformations

The presentation, paper and magazine articles are provided by clicking here.

To jump straight to the animations in a YouTube playlist click here.