Toric Contact Lens Back Surface Design for Pressure Uniformity

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Solution Overview

Problem

Existing toric contact lenses face challenges in maintaining rotational stability and minimizing corneal pressure across a range of cylinder powers, leading to discomfort and potential corneal staining due to uneven contact pressure distribution.

Innovation Solution

The optimization of the back surface design for toric contact lenses involves adjusting the sag and radius of curvature of the peripheral zone and increasing the outer diameter of the transition zone, while selecting a reference meridian that balances slope deviations, thereby reducing the differential in corneal pressure across various cylinder powers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the back surface design is optimized for a specific cylinder power, then the optical correction is improved, but the contact pressure becomes uneven across different cylinder powers

Engineering Contradiction:

Improveoptical correction precisionVSAvoidcorneal contact pressure distribution

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

The patent applies parameter changes by adjusting the sag and radius of curvature of the peripheral zone, and increasing the outer diameter of the transition zone, to optimize the back surface geometry. These parameter modifications reduce the differential in corneal pressure across various cylinder powers while maintaining optical correction precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by creating a transition zone with specific geometric characteristics that differ from both the optic zone and peripheral zone. This localized region with optimized sag, radius of curvature, and outer diameter provides uniform contact pressure distribution specifically where needed, while maintaining the optical properties of the central zone.

Inventive Principle:

Principle #3Local quality

2Stress or pressure

If the transition zone outer diameter is increased, then the contact pressure uniformity is improved, but the lens geometry complexity increases

Engineering Contradiction:

Improvecontact pressure uniformityVSAvoidlens geometry complexity

Core Design Contradiction:

Stress or pressureVSDevice complexity

Solution Approach 1:

The patent resolves this contradiction by optimizing the transition zone outer diameter parameter to a specific value that achieves contact pressure uniformity without excessive complexity. The parameter is adjusted to the minimum necessary size to achieve the desired pressure distribution, avoiding unnecessary geometric complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250102829A1Optimized Posterior Surface for Toric Contact Lenses

Publication Date: 2025.03.27 JOHNSON & JOHNSON VISION CARE INC

AI summary

A method for improving a reference set of soft toric contact lenses, an improved set of toric contact lenses and an improved toric lens are provided. The method involves identifying geometric characteristics of the reference lenses including at least a target sphere power, a radius of curvature of the posterior surface of the peripheral zone, a lens center thickness, a lens material refractive index, the optic zone diameter and an outer diameter of said transition zone; identifying a reference meridian of the reference set of toric lenses; reducing slope deviations along the reference meridian by adjusting a sag and the radius of curvature of the peripheral zone, and/or increasing the outer diameter of the transitional zone; and creating the improved set of lenses by applying the adjusted sag and radius of curvature, and/or increased outer diameter of the transition zone to all lenses within the improved set of lenses.