Foldable Intraocular Lens Step Edge Haptic Design
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Solution Overview
Problem
One-piece intraocular lenses (IOLs) face challenges with posterior capsular opacification (PCO) due to bulky haptics, which increase the incidence of PCO and are difficult to design with a step edge configuration that balances stiffness and volume for small incision delivery, while also minimizing optical aberrations.
Innovation Solution
A foldable intraocular lens with an integrally formed haptic featuring a step edge around the posterior edge of the optical zone, where the haptic thickness is greater than or equal to the optic edge thickness, and a peripheral zone that surrounds the optical zone, providing a continuous surface and reducing the overall lens volume for small incision delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bulky haptics are used in one-piece IOLs to provide rigidity and support, then the haptics can prevent distal portions from sticking to the optic, but the bulky haptics increase the incidence of posterior capsular opacification (PCO)
Solution Approach 1:
The haptic is divided into multiple thickness zones: a thicker proximal portion for rigidity and support, and a thinner distal portion that reduces interference with capsule attachment. This segmentation allows the haptic to provide necessary structural support while minimizing the bulky effect that promotes PCO.
Solution Approach 2:
Different portions of the haptic have different thicknesses and rigidity characteristics tailored to their specific functions. The proximal portion is thicker and stiffer for structural support, while the distal portion is thinner to reduce interference with capsule attachment, creating local quality variations that resolve the contradiction.
2Volume of moving object
If the optic edge is made thin to reduce overall IOL volume, then the IOL can be delivered through smaller incisions, but the haptic becomes too thin to provide sufficient stiffness when a step edge is incorporated
Solution Approach 1:
The haptic is segmented into different thickness portions: a thinner optic edge for reduced volume and a thicker proximal haptic portion for sufficient stiffness. This segmentation allows the IOL to have reduced overall volume while maintaining adequate haptic rigidity for proper function.
Solution Approach 2:
The haptic thickness varies along its length, transitioning from thinner at the optic edge to thicker at the proximal portion. This dimensional variation allows the design to achieve both reduced volume and sufficient stiffness by optimizing thickness in different spatial locations.
3Strength
If the optic edge is made thick to provide attachment area for thicker haptics and room for step edge, then haptic stiffness is improved, but the overall IOL volume becomes too large leading to undesirably large incisions
Solution Approach 1:
The IOL structure is segmented into different thickness zones: the optic edge and distal haptic are thinner to reduce volume, while the proximal haptic is thicker to provide sufficient stiffness and attachment area. This segmentation resolves the contradiction by distributing different thickness requirements to appropriate locations.
Solution Approach 2:
Different regions of the IOL have different thickness characteristics optimized for their specific functions. The proximal haptic region is locally thickened to provide stiffness and attachment area, while other regions remain thin to minimize overall volume, creating local quality variations that resolve the contradiction.
Data Source
AI summary
A foldable intraocular lens for providing vision contains an optic body that includes an optical zone and a peripheral zone entirely surrounding the optical zone. The optic body has an anterior face, a substantially opposing posterior face, an optic edge, and an optical axis. The anterior face comprises a central face, a peripheral face, and a recessed annular face therebetween that is disposed posterior to the peripheral face. The intraocular lens further comprises at least one haptic that is integrally formed with the peripheral zone. The haptic comprises a distal posterior face, a proximal posterior face, and a step edge disposed at a boundary therebetween. The haptic further comprises a side edge disposed between the optic edge and the step edge. The proximal posterior face and the posterior face of the optic body form a continuous surface. An edge corner is formed by the intersection of the continuous surface with the optic edge, the side edge, and the step edge.