Customized Refractive Correction Using Objective Wavefront Sensing
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Solution Overview
Problem
Conventional refractive correction methods, such as manifest refraction, are limited by subjective measurements and high tolerance in lens manufacturing, leading to inaccurate and variable prescriptions for cylindrical errors, while wavefront-guided corrections face challenges in precise lens manufacturing and alignment, resulting in suboptimal vision correction.
Innovation Solution
A method combining objective wave aberration measurements for cylindrical power and axis with subjective refraction for focus power to generate customized refractive prescriptions for ophthalmic lenses with resolutions finer than 0.25 D, using toric surfaces and advanced lens manufacturing techniques to achieve precise control of cylindrical power, and a phoroptor with wavefront sensing for accurate alignment and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional manifest refraction is used, then the process is simple and time-efficient, but the measurement precision of cylindrical error is limited to 0.25 D and varies by practitioner
Solution Approach 1:
The patent replaces the manual, subjective mechanical process of manifest refraction with an automated objective wavefront sensing system. The wavefront aberrometer objectively measures all aberrations including cylindrical error without requiring practitioner or patient subjectivity, thereby improving measurement precision while reducing process complexity through automation.
Solution Approach 2:
The patent uses objective wavefront sensing to create a precise digital copy of the eye's optical aberrations. This digital representation allows for high-precision measurement of cylindrical error without the limitations of physical lens testing, enabling reproducible results independent of practitioner expertise.
2Manufacturing precision
If conventional lens manufacturing tolerances are used, then the manufacturing process is simple and cost-effective, but the manufacturing precision of cylindrical power is limited to ±0.09-0.37 D
Solution Approach 1:
The patent changes the manufacturing parameters by specifying cylindrical power with a resolution finer than 0.25 D (e.g., 0.125 D or 0.0625 D steps). This finer parameter resolution enables precision beyond conventional tolerances while maintaining manufacturability through computer-controlled lens surfacing equipment that can achieve these tighter tolerances.
Solution Approach 2:
The patent performs preliminary objective measurement of the eye's wavefront aberrations to determine the precise cylindrical error before lens manufacturing. This advance knowledge allows the lens to be manufactured with targeted precision, and any residual error can be compensated through custom toric surface design rather than requiring ultra-precise manufacturing from the start.
3Measurement precision
If wavefront-guided correction is used, then the measurement precision of all aberrations is improved, but the device complexity and alignment requirements increase
Solution Approach 1:
The patent segments the refractive correction into distinct components: objective wavefront measurement of all aberrations, subjective refraction for focus error, and separate customization of toric surfaces for cylindrical correction. This segmentation allows each component to be optimized independently, reducing the overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The patent merges objective wavefront sensing with subjective refraction in a unified process that combines the advantages of both approaches. The objective measurement provides precise aberration data while the subjective process ensures optimal focus error correction, and the results are integrated to create a customized prescription that leverages the strengths of both methods.
4Measurement precision
If subjective refraction is used, then the focus error correction is optimized based on patient response, but the process is time-consuming with three independent variables
Solution Approach 1:
The patent performs preliminary objective measurement of wavefront aberrations to obtain precise estimates of focus error, cylindrical error, and axis orientation before the subjective refraction process. This advance information reduces the number of iterations needed during subjective testing, allowing the practitioner to focus only on refining the focus error correction rather than searching through multiple variables.
Solution Approach 2:
The patent uses objective wavefront measurement as an intermediary that bridges the gap between the patient's subjective visual responses and the actual optical aberrations. This intermediary provides objective data that guides the subjective process, reducing the time needed to optimize focus error correction by eliminating unnecessary trial-and-error adjustments.
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
This approach enables precise and customized refractive corrections, achieving visual acuity of 20/10 for most eyes by accurately determining and correcting cylindrical errors, reducing astigmatism, and improving night vision, while simplifying lens manufacturing and alignment processes.
Implementation Method 1
an objective measurement of a wave aberration of the eye is obtained without the use of a patient's responses
Implementation Method 2
correcting an eye's astigmatism using conventional vision correction... a customized prescription for an ophthalmic lens... toric surfaces
Data Source
AI summary
Methods and devices are provided to obtain refractive correction with superior visual acuity (e.g., 20/10) by achieving an astigmatism-free customized refractive correction. The astigmatism-free customized refractive correction involves obtaining an objective and precise measurement of cylindrical power in a resolution between 0.01 D and 0.10 D in an eye using an objective aberrometer, reliably relating the cylindrical axis obtained from the objective aberrometer to that in a phoroptor, determining an optimized focus error of an eye through subjective refraction with a phoroptor, generating a customized refraction by combining the objective measured cylindrical power, the objective measured cylindrical axis, and the subjectively measured focus power, fabricating a custom lens with a tolerance finer than 0.09 D based on the generated customized refraction, and delivering an ophthalmic lens that can provide an astigmatism-free refractive correction for an eye.