Nomograph Calibration for Corneal Laser Astigmatism Correction
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Solution Overview
Problem
Current methods for correcting astigmatism through LASIK surgery are unpredictable, relying on subjective patient feedback and resulting in varying outcomes due to the cornea's ability to heal and change shape post-treatment, making it difficult to accurately determine the success of astigmatism correction.
Innovation Solution
A system calculates nomographs based on the difference between expected and actual astigmatism coefficients using Zernike polynomials, allowing for calibration of correction coefficients for subsequent LASIK treatments by analyzing pre-operative, correction, expected, and actual astigmatism coefficients in a sample population, thereby improving the accuracy of astigmatism correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LASIK surgery is performed to correct astigmatism, then visual acuity is improved, but the outcome varies between patients due to corneal healing and shape changes
Solution Approach 1:
The system implements feedback by measuring actual post-operative astigmatism coefficients and using these measurements to update and refine correction algorithms. The nomograph is generated based on accumulated data from multiple patients, creating a feedback loop that continuously improves prediction accuracy for future surgeries.
Solution Approach 2:
The system changes parameters by transitioning from theoretical correction coefficients to empirically-derived nomograph values. The nomograph provides adjusted correction coefficients that account for actual corneal healing patterns observed in the patient population, transforming the correction approach from purely theoretical to evidence-based.
2Loss of information
If traditional subjective patient feedback is used to assess correction success, then patient perception is captured, but objective measurement accuracy is reduced
Solution Approach 1:
The system replaces the subjective mechanical assessment (patient feedback) with an objective optical measurement system. By using instruments to directly measure corneal astigmatism coefficients, the system substitutes human perception with precise optical instrumentation, eliminating subjectivity while maintaining comprehensive outcome assessment.
3Device complexity
If correction coefficients are based on theoretical calculations, then treatment planning is simplified, but actual correction accuracy decreases due to corneal healing
Solution Approach 1:
The system performs preliminary action by pre-calculating nomograph values based on accumulated surgical outcomes before actual surgery. These pre-computed nomograph values are ready for use in treatment planning, allowing surgeons to apply empirically-refined correction coefficients without performing complex real-time calculations during patient consultations.
Data Source
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AI summary
A method for to calculation of actual astigmatism correction and nomographs for corneal laser treatment includes performing a post-operative measurement of the cornea of a patient to determine actual astigmatism coefficients. The actual astigmatism coefficients are compared against the expected astigmatism coefficients to generate a nomograph value or a nomograph curve over a sample population. The nomograph is used to calibrate subsequent laser treatments for improved accuracy of clinical results.