Composite Soft Contact Lens Stiff Optic Zone Astigmatism Correction

Solution Overview

Problem

Current toric contact lenses for astigmatism correction often require stabilization mechanisms to maintain orientation on the eye, which can be uncomfortable and less effective, especially for plus powered lenses, due to their reliance on eyelid interaction and thickness differentials.

Innovation Solution

The development of composite soft contact lenses with a central optic zone made from silicone hydrogels having a higher Young's modulus, formed from reactive mixtures containing N-alkyl methacrylamide, silicone components, and cross-linking agents, providing sufficient stiffness for vaulting over the cornea without causing discomfort, while the peripheral zone remains soft for comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a toric contact lens uses stabilization mechanisms to maintain orientation on the eye, then astigmatism correction is improved, but comfort deteriorates due to reliance on eyelid interaction and thickness differentials

Engineering Contradiction:

Improveastigmatism correctionVSAvoidcomfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The contact lens incorporates a central optic zone with higher Young's modulus (stiffer material) surrounded by a peripheral zone with lower Young's modulus (softer material). This local differentiation in material properties allows the central zone to maintain optical stability for astigmatism correction while the softer peripheral zone enhances comfort by conforming to the cornea without requiring aggressive stabilization mechanisms

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The lens is constructed as a composite structure with two distinct material regions: a central zone made from silicone hydrogel with higher modulus and a peripheral zone with lower modulus. This composite approach enables simultaneous achievement of optical reliability and comfort by assigning different material properties to different functional zones of the lens

Inventive Principle:

Principle #40Composite materials

2Reliability

If the central optic zone is made stiffer to vault over the cornea, then optical correction is improved, but comfort may worsen due to potential discomfort from stiffness

Engineering Contradiction:

Improveoptical correctionVSAvoidcomfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The contact lens incorporates a central optic zone with higher Young's modulus (stiffer material) surrounded by a peripheral zone with lower Young's modulus (softer material). This local differentiation in material properties allows the central zone to maintain optical stability for astigmatism correction while the softer peripheral zone enhances comfort by conforming to the cornea without requiring aggressive stabilization mechanisms

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The lens is constructed as a composite structure with two distinct material regions: a central zone made from silicone hydrogel with higher modulus and a peripheral zone with lower modulus. This composite approach enables simultaneous achievement of optical reliability and comfort by assigning different material properties to different functional zones of the lens

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design allows for effective astigmatism correction with reduced reliance on stabilization mechanisms, enhancing comfort and maintaining optical correction by creating a tear lens with matching refractive index to neutralize corneal toricity, thus improving vision without the need for rotational alignment.

Implementation Method 1

The higher modulus hydrogel material creates a stiffer central optic zone relative to the peripheral zone of the contact lenses

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

Since the index of refraction of the fluid or tear lens is nearly a match for the cornea, the corneal toricity is optically neutralized or reduced

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS11829008B2Increased stiffness center optic in soft contact lenses for astigmatism correction

Publication Date: 2023.11.28 JOHNSON & JOHNSON VISION CARE INC

AI summary

A molded contact lens comprising a stiffer optic zone relative to the peripheral zone of the contact lens provides an optical element for correcting astigmatism without the need for or substantially minimizing the need for the correction of rotational misalignment. The higher elastic modulus optic zone vaults over the cornea thereby allowing a tear lens to form. The tear lens follows or assumes the shape of the back surface of the contact lens. The combination of the tear lens and the optical zone provide an optical element for correction of refractive error.