Foldable Intraocular Lens Step Edge Haptic Design
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Solution Overview
Problem
One-piece intraocular lenses (IOLs) face increased incidence of posterior capsule opacification (PCO) due to bulky haptics, which compromise the blockage of cell growth and attachment of the anterior capsule to the posterior capsule, leading to a higher incidence compared to three-piece IOLs, and existing designs that reduce IOL volume may introduce optical issues like halos and poor contrast.
Innovation Solution
A foldable intraocular lens with an integrally formed haptic featuring a step edge around the entire posterior edge of the optical zone, which is contiguous and helps prevent cell migration, while maintaining a small overall volume suitable for delivery through small ocular incisions, and incorporates a peripheral zone with a recessed annular face and a cross-sectional profile that reduces optical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If one-piece IOL design is used with integrally formed haptics, then manufacturing simplicity is improved, but posterior capsule opacification incidence increases due to bulky haptics compromising cell growth blockage
Solution Approach 1:
The haptic is divided into two distinct regions: a thinner equatorial region that provides a sharp corner seal to block cell migration, and a thicker proximal region that provides structural support and rigidity. This segmentation allows each region to be optimized for its specific function while maintaining the one-piece construction advantage.
Solution Approach 2:
Different thicknesses are applied to different portions of the haptic structure. The equatorial portion has reduced thickness to minimize bulk and enable effective corner sealing, while the proximal portion maintains greater thickness for mechanical support. This local variation in quality resolves the contradiction between manufacturing simplicity and PCO prevention.
2Volume of moving object
If optic edge is made thinner to reduce overall IOL volume, then incision size is reduced, but haptic stiffness is compromised
Solution Approach 1:
The optic edge thickness is locally varied to accommodate both reduced volume and maintained haptic stiffness. The peripheral zone where the haptic attaches has sufficient thickness to provide structural support, while other portions of the optic can be thinner to reduce overall volume. This local quality differentiation allows the haptic to maintain stiffness without requiring the entire optic to be thick.
Solution Approach 2:
The solution moves from a uniform thickness approach to a multi-dimensional thickness profile. The haptic structure incorporates vertical thickness variations (proximal vs. equatorial regions) and the optic has differentiated thickness zones, allowing volume reduction in non-critical areas while maintaining structural integrity where needed.
3Strength
If optic edge is made thicker to provide attachment area for stiffer haptic, then haptic rigidity is improved, but overall IOL volume increases
Solution Approach 1:
The haptic attachment structure is segmented into the peripheral zone of the optic and the haptic itself, with the haptic further divided into proximal and equatorial regions. This segmentation allows the attachment area to be optimized for rigidity while the rest of the IOL maintains reduced volume through thinner construction in non-critical areas.
4Object-affected harmful factors
If step edge is incorporated in haptic area, then posterior capsule opacification is reduced through continuous edge seal, but IOL volume and incision size increase
Solution Approach 1:
The step edge structure is segmented into a first thickness region providing the corner seal and a second thickness region providing structural support. This segmentation allows the step edge to effectively block cell migration while minimizing the volume added by the step structure, as only the necessary portions are thickened.
Solution Approach 2:
The step edge incorporates local thickness variations where the first portion has reduced thickness for effective sealing while the second portion maintains greater thickness for structural support. This local quality differentiation enables PCO prevention without requiring uniform thickening that would increase overall volume.
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.