Intraocular Lens Haptic Step Feature for PCO Prevention
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Solution Overview
Problem
Intraocular lenses (IOLs) face issues with posterior capsular opacification (PCO) due to epithelial cell migration and unpredictable vaulting after implantation, which affects the final position and refractive performance of the lens.
Innovation Solution
The design incorporates a substantially circular optic with haptics featuring a step feature on the posterior surface and a taper surface on the anterior surface, along with a central optic plane that divides the optic edge surface, preventing epithelial cell migration and minimizing vaulting by creating a barrier angle and facilitating anterior bending of the haptics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the haptic is radially compressed during implantation or after implantation, then the haptic can be seated within the capsular bag, but the refractive region vaults or pushes forwardly (anteriorly) in the eye
Solution Approach 1:
The haptic is divided into distinct segments: a compression-resistant portion that maintains structural integrity during implantation, and a compression-sensitive portion that allows controlled bending. This segmentation enables the haptic to be seated in the capsular bag while minimizing unwanted vaulting of the refractive region.
Solution Approach 2:
Different portions of the haptic are designed with different mechanical properties. The compression-resistant portion has higher rigidity to prevent excessive bending, while the compression-sensitive portion has lower rigidity to allow necessary deformation during implantation. This local differentiation of mechanical properties resolves the contradiction between ease of seating and position predictability.
2Ease of operation
If the haptic is radially compressed during implantation, then the haptic can be inserted through a small incision, but epithelial cells migrate from the haptic to the refractive region causing PCO
Solution Approach 1:
A barrier layer is introduced as an intermediary between the haptic and the refractive region. This barrier layer prevents epithelial cells from migrating from the haptic surface to the refractive region, thereby eliminating PCO while maintaining the benefits of minimally invasive implantation.
Solution Approach 2:
The haptic design incorporates features that automatically prevent epithelial cell migration without requiring additional surgical interventions. The compression-resistant portion maintains a stable configuration that reduces epithelial cell contact with the refractive region, providing self-protection against PCO.
3Manufacturing precision
If the haptic is made more rigid to prevent vaulting, then the final lens position becomes more predictable, but the haptic cannot be properly seated within the capsular bag
Solution Approach 1:
The haptic is segmented into compression-resistant and compression-sensitive portions with different rigidities. The compression-resistant portion provides the necessary stiffness for position predictability, while the compression-sensitive portion allows flexibility for seating in the capsular bag, thus resolving the contradiction between rigidity and ease of implantation.
Solution Approach 2:
The haptic is designed to exhibit dynamic mechanical behavior: it is flexible during implantation to allow seating, and becomes more rigid after implantation to maintain predictable positioning. This dynamic adaptation of mechanical properties resolves the contradiction between ease of operation and position predictability.
Data Source
AI summary
An intraocular lens comprises an optic and at least two haptics, each of which comprises a step feature that protrudes from a posterior surface of the haptic to prevent posterior capsular opacification.