Intraocular Lens Power Calculation Using Corneal Spherical Aberration
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Solution Overview
Problem
Current regression formulas for calculating intraocular lens (IOL) power, such as SRK, SRKII, and SRK/T, fail to accurately predict the necessary power for achieving emmetropia, especially in eyes with extreme myopia or hyperopia, and do not account for corneal aberrations, leading to inaccuracies in refractive outcomes, particularly for post-lasik patients.
Innovation Solution
A method and system that incorporate corneal spherical aberrations into a modified regression formula, using empirically derived constants to estimate IOL power, which includes the product of corneal spherical aberration with an empirically derived constant and biometric parameters like axial length and corneal power, to predictively select an IOL that achieves a desired postoperative refractive condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional regression formulas (SRK, SRKII, SRK/T) are used for IOL power calculation, then the calculation process is simple and quick, but the prediction accuracy is insufficient especially for extreme myopia or hyperopia and post-lasik patients
Solution Approach 1:
The patent modifies the traditional regression formula by adding a new parameter - corneal spherical aberration coefficient. This transforms the conventional IOL power calculation into a new regression formula that incorporates aberration parameters, thereby improving prediction accuracy for extreme cases and post-lasik patients while maintaining the regression-based calculation framework
Solution Approach 2:
The patent separates the IOL power calculation into two components: the traditional regression-based power calculation and the additional aberration compensation term. This segmentation allows the system to maintain the simplicity of traditional formulas while adding precision through the aberration coefficient, resolving the contradiction between simplicity and accuracy
2Adaptability or versatility
If regression formulas are based on average emmetropic eyes, then the formulas work well for average patients, but they produce errors for extreme myopia or hyperopia and non-average eye configurations
Solution Approach 1:
The patent applies local quality by introducing patient-specific corneal spherical aberration coefficients that vary according to individual eye characteristics. Instead of using a universal average-based formula, the calculation is customized for each patient's specific aberration profile, improving accuracy for extreme myopia, hyperopia, and post-lasik eyes while maintaining effectiveness for average cases
Data Source
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AI summary
An intraocular lens, and a system and method of providing an intraocular lens, having at least one characteristic of the intraocular lens customized in accordance with a modified regression that includes a modification for corneal spherical aberration. The lens, system and method may indicate measuring at least one biometric parameter of an eye at a desired light level, determining a desired postoperative condition of the eye, obtaining a corneal spherical aberration of the eye, applying at least one empirically derived regression calculation, and predictively estimating, in accordance with an output of the at least one empirically derived regression calculation, the at least one characteristic of the intraocular lens to obtain the desired postoperative condition. The empirically derived regression calculation includes at least a product of the corneal spherical aberration with an empirically derived corneal spherical aberration constant, and a mathematical indication of the at least one biometric parameter or one of the paraxial regression formulas commonly used in clinical practice to calculate IOL power in normal patients.