Corneal Laser Cutting via Segmented Focus Path
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Solution Overview
Problem
Existing methods for creating cutting planes in the cornea using pulsed laser radiation face challenges in achieving high accuracy and minimizing collateral damage, particularly with two-dimensional deflection strategies that either result in central bubbles causing vision issues or difficulties in positioning the focus due to peripheral bubbles.
Innovation Solution
The method involves guiding the focal point in two partial steps with a decreasing path radius in one step and an increasing path radius in the other, allowing for an overlapping zone between sections, with the cut initiated from the outside in for the inner section and from the inside out for the outer section, enabling precise control of the cutting plane formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the laser focus is guided in a single continuous path for cutting plane generation, then the process is simple, but central bubbles are formed causing vision issues and peripheral bubbles make focus positioning difficult
Solution Approach 1:
The cutting plane generation process is divided into two distinct sections: a first section where the focus is guided from the outside in with decreasing path radius, and a second section where the focus is guided from the inside out with increasing path radius. This segmentation allows each section to be optimized independently, preventing bubble formation in problematic areas while maintaining cutting accuracy.
Solution Approach 2:
The patent applies reverse cutting directions for different sections of the cutting plane. The first section cuts from the outside in, while the second section cuts from the inside out. This inversion strategy prevents bubbles from forming in the center of the cornea (which would cause vision issues) and avoids peripheral bubbles that would interfere with focus positioning.
2Manufacturing precision
If high focusing of laser beam with very short pulses is applied, then pinpoint accuracy is achieved, but precise control of cutting plane formation becomes difficult
Solution Approach 1:
The patent employs dynamic control of the laser focus path, transitioning between different guidance strategies in the first and second sections. The focus path radius decreases in the first section and increases in the second section, allowing adaptive control to maintain pinpoint accuracy while facilitating precise cutting plane formation through controlled bubble dynamics.
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 the quality of cutting plane generation by reducing collateral damage and improving precision, allowing for more accurate refractive corrections and flap creation in ophthalmic surgery by minimizing bubble formation and facilitating precise focus positioning.
Implementation Method 1
the treatment laser radiation within the tissue, i.e. beneath the tissue surface, is focused in such a way that optical breakthroughs in the tissue are formed. If the power density of the radiation exceeds a threshold value, an optical breakthrough will occur, generating a plasma bubble in the material.
Implementation Method 2
an optical breakthrough will occur, generating a plasma bubble in the material. After the optical breakthrough has been generated, said plasma bubble grows due to expanding gases.
Implementation Method 3
If a plasma is generated at a material boundary, which may also be located within a material structure, material will be removed from said boundary. This boundary phenomenon is then referred to as photoablation.
Implementation Method 4
In connection with a plasma bubble which separates previously connected material layers, the term photodisruption is usually applied.
Implementation Method 5
a laser radiation source, which focuses laser radiation into the material and effects optical breakthroughs therein, whereby a scan unit, which shifts the focal point three-dimensionally
Data Source
AI summary
A method and a device for forming cut surfaces in a transparent material, particularly in the cornea, by producing optical breakthroughs in the material by application of laser radiation focused into the material. The focal point is adjusted in three dimensions to form the cut surface by the sequential arrangement of optical perforations. The focal point is guided in such a manner that cutting is divided into at least two steps, and in at least one of the steps, the formation of the cut is carried out with a path radius that decreases in size, and in one of the steps, the cut formation is carried out with a path radius that increases in size.