Customized Flap Shapes for LASIK Refractive Precision
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Solution Overview
Problem
Current LASIK methods face challenges in achieving optimal refractive outcomes due to limitations in flap shape and ablation profile precision, leading to issues like flap shrinkage and creasing, which result in postoperative optical aberrations and suboptimal image formation on the retina.
Innovation Solution
A control program for a pulsed laser system that calculates and generates customized flap shapes and diameters based on empirical data, allowing for non-axisymmetric flaps with projections for anchorage, which can be controlled using a computer to direct a femtosecond laser for precise photodisruptive cutting, addressing flap shrinkage and creasing by enabling three-dimensional shaping and fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional LASIK methods with standard flap shapes are used, then the surgical procedure is simple and quick, but postoperative optical aberrations occur and refractive outcomes are suboptimal
Solution Approach 1:
The patent applies local quality by creating non-axisymmetric flap shapes with different diameters in different axes (e.g., larger diameter in the meridian perpendicular to the hinge, smaller diameter in the hinge direction). This localized variation in flap dimensions optimizes the refractive outcome by matching the ablation profile requirements in different regions of the cornea, thereby reducing optical aberrations while maintaining surgical feasibility.
Solution Approach 2:
The patent employs asymmetry by deliberately designing flaps with non-uniform dimensions across different axes. The flap diameter is made asymmetric relative to the ablation profile, with specific emphasis on creating larger diameters in certain meridians and smaller diameters in others. This asymmetric design compensates for optical aberrations and improves refractive outcomes by optimizing light distribution across the treated zone.
2Reliability
If flap diameter is increased to prevent shrinkage, then anchorage is improved, but more corneal tissue is removed and healing time increases
Solution Approach 1:
The patent applies local quality by varying the flap diameter locally in different directions. The flap has a larger diameter in the meridian perpendicular to the hinge to ensure adequate anchorage and prevent shrinkage, while maintaining a smaller diameter in the hinge direction to minimize tissue removal and accelerate healing. This localized differentiation allows simultaneous optimization of anchorage reliability and healing time.
3Manufacturing precision
If axisymmetric circular flaps are used, then the surgical process is simple and standardized, but optical aberrations occur due to mismatch with non-axisymmetric ablation profiles
Solution Approach 1:
The patent employs asymmetry by designing flaps with non-axisymmetric dimensions that specifically match the ablation profile geometry. The flap diameter is made asymmetric, with larger dimensions in meridians perpendicular to the hinge and smaller dimensions in the hinge direction. This asymmetric design compensates for optical aberrations caused by mismatched ablation profiles, thereby improving optical precision while maintaining surgical feasibility through computer-controlled laser systems.
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 enhances postoperative refractive results by minimizing higher-order optical aberrations and ensuring accurate flap fitting, reducing the likelihood of undesirable postoperative faults like flap shrinkage and creasing, while allowing for true-to-shape folding and anchoring, thereby improving surgical precision and patient outcomes.
Implementation Method 1
a laser is also used for generating the flap. To this end in particular FS lasers (femtosecond lasers) are used, the radiation of which is focused in the stroma below the surface of the cornea so as to photodisruptively cause tissue separation at a multiplicity of adjacent positions there
Data Source
AI summary
The present invention relates to a method for generating a control program for ophthalmologic LASIK surgery, with which a pulsed laser system can be controlled for the photodisruptive cutting of a flap, having the following steps: obtaining empirical data, which relate to the effect in particular of flap shapes and ablation profiles on postoperative refractive results, obtaining measurement data relating to the eye to be treated, calculating an optimal cutting shape for the photodisruptive cutting of the flap by taking into account the said empirical data and the said measurement data, and generating the control program on the basis of the calculated cutting shape.