Undercut Ledge Contact Lens for Lid-Driven Translation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current contact lenses, particularly soft bifocal lenses, face challenges in translating across the eye's surface when changing from distance to near vision due to their ability to conform closely to the cornea, limiting users to either uncomfortable hard lenses or monofocal soft lenses, and existing solutions like translation ridges on the front surface often fail to engage the lid effectively.
Innovation Solution
A contact lens design featuring a front surface with multiple zones for distance and near vision correction, including an undercut ledge zone that engages the lower eyelid to facilitate vertical translation, allowing for large amplitude movement, and a manufacturing method using a mold with undercut features to support this design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a translation ridge is added to the front surface of the lens, then the lens translation capability is improved, but the lid engagement is insufficient and the lens does not translate effectively
Solution Approach 1:
Instead of adding a ridge to the front surface of the lens, the invention inverts the approach by adding an undercut ledge to the back surface of the lens. This inverted design allows the lower lid to engage directly with the ledge, providing reliable mechanical engagement that enables effective lens translation without the lid rolling over a front-surface ridge.
Solution Approach 2:
The undercut ledge acts as an intermediary structure between the lens and the lower lid. It provides a dedicated engagement surface that facilitates the interaction between the lens and lid, ensuring reliable mechanical coupling that enables the lens to translate effectively across the eye surface.
2Reliability
If the ridge is positioned nearer to the center of the lid, then the lid can engage the ridge, but the lower lid does not provide enough movement for effective amplitude of lens translation
Solution Approach 1:
The invention extends the engagement interaction into a third dimension by creating an undercut ledge that projects backward from the back surface of the lens. This vertical dimension allows the lower lid to engage the ledge and pull the lens downward, providing sufficient translation amplitude while maintaining reliable engagement.
3Ease of operation
If an undercut feature is added to the lens design, then the lens translation is enabled, but the manufacturing process becomes more complex requiring slides in the mold bases
Solution Approach 1:
The mold design incorporates preliminary actions by including a slide mechanism that is positioned and configured in advance during mold fabrication. This slide is pre-positioned to receive the lens blank during injection molding, allowing the undercut ledge to be formed as an integral part of the lens structure without requiring post-manufacturing modifications or complex multi-step processes.
Data Source
AI summary
The present invention is directed to a contact lens design where the optics position relative to the pupil is controlled by the lens relationship to the lower lid.