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 optimal IOL power for eyes with extreme refractive states or those that have undergone LASIK surgery, as they do not account for corneal spherical aberrations, leading to inaccuracies in achieving emmetropia.
Innovation Solution
A modified regression formula that incorporates corneal spherical aberration, using the equation P=A*Formula+D*(corneal spherical aberration)+E, where D and E are empirically derived constants, to optimize IOL power calculations, ensuring accurate prediction of IOL power for both average and non-average eyes, including post-LASIK patients.
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 for eyes with extreme refractive states or post-LASIK eyes
Solution Approach 1:
The patent modifies the traditional regression formula by adding a new parameter term: D*(corneal spherical aberration). This transforms the original formula P=A-2.5*AXL-0.9*K into an enhanced version P=A*Formula+D*(corneal spherical aberration)+E, where D and E are empirically derived constants. This parameter addition directly addresses the inaccuracy for extreme refractive states and post-LASIK eyes while maintaining the regression-based calculation framework.
Solution Approach 2:
The patent introduces corneal spherical aberration as an intermediary parameter that mediates between the traditional biometric measurements and the final IOL power prediction. This intermediary term captures the optical quality of the cornea, which is particularly important for post-LASIK eyes where corneal geometry has been altered, thereby improving prediction accuracy without completely replacing the established regression methodology.
2Reliability
If the regression formula is modified to include corneal spherical aberration, then the accuracy for post-LASIK eyes improves, but the calculation requires additional measurements and constants
Solution Approach 1:
The patent performs preliminary action by empirically deriving the constants D and E from clinical data before actual IOL power calculations. This pre-calculation of constants allows the modified formula to be applied routinely without requiring complex real-time computations, thereby maintaining ease of operation while improving reliability for post-LASIK eyes.
3Adaptability or versatility
If traditional formulas are used, then emmetropia can be achieved for average eyes, but errors arise for extreme myopia or hyperopia and non-average eye configurations
Solution Approach 1:
The patent enhances the adaptability of the regression formula by incorporating corneal spherical aberration as an additional parameter. This modification allows the formula to adapt to various refractive states including extreme myopia and hyperopia, as well as non-average eye configurations, thereby improving measurement precision across diverse patient populations while maintaining the versatility of the regression approach.
Data Source
AI summary
A system for predicting optical power for an intraocular lens based upon measured biometric parameters in a patient's eye includes: a biometric reader capable of measuring one or more biometric parameters of the patient's eye and obtaining at least one value for at least one of the one or more biometric parameters, and further measuring a representation of a corneal topography of the patient's eye; a processor; and a computer readable medium coupled to the processor and having stored thereon a program that upon execution causes the processor to: receive the at least one value; obtain a corneal spherical aberration (SA) based upon the representation of the corneal topography; and calculate an optimized optical power to obtain a desired postoperative condition by applying the received at least one value and the obtained corneal spherical aberration to a modified regression.