Cornea Cutting Surface Radially Stepped Profile
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Solution Overview
Problem
Current methods for refractive laser corrections in eye surgery face challenges in maintaining corneal stability, especially for strong optical corrections, often resulting in residual stromal thickness that impairs optical quality and limits the extent of correction possible.
Innovation Solution
A planning device that generates control data for a treatment device to create a cornea cutting surface composed of multiple sub-surfaces, allowing for a radially stepped lenticule profile that reduces maximum lenticule thickness and introduces abrupt changes in thickness at specific radii, enabling corrections beyond previous minimum thickness limitations while ensuring corneal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser correction methods are used to achieve strong optical corrections, then the refraction correction effect is improved, but the residual stromal thickness becomes insufficient which impairs corneal stability and biomechanical integrity
Solution Approach 1:
The cutting surface is divided into multiple sub-surfaces (first, second, third sub-surfaces) with different orientations and functions. The first sub-surface creates an initial cut, the second sub-surface creates a parallel cut at a distance, and the third sub-surface connects them at an angle, segmenting the correction process to achieve both precision and stability
Solution Approach 2:
Different regions of the cutting surface are assigned different properties: the first and second sub-surfaces are substantially parallel to the optical axis for precise depth control, while the third sub-surface is angled to create the desired refraction effect, allowing local optimization of both correction precision and corneal stability
2Adaptability or versatility
If the residual stromal thickness is reduced to enable more extensive corrections, then the refraction correction range is improved, but the biomechanical stability of the cornea deteriorates
Solution Approach 1:
The cutting surface is extended into the third dimension by creating a multi-layered structure with sub-surfaces at different depths and angles. This volumetric approach allows correction of larger refractive errors while preserving sufficient stromal thickness in critical regions for biomechanical stability
3Ease of operation
If a single cutting surface is used for correction, then the treatment simplicity is maintained, but the ability to correct large sight defects is limited due to minimum thickness requirements
Solution Approach 1:
The first sub-surface creates a preliminary cut that establishes the initial geometry and depth, preparing the cornea for subsequent cuts. This preliminary action allows the second and third sub-surfaces to achieve the final precise correction geometry without compromising minimum thickness requirements
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 allows for more extensive refractive corrections over the entire optical zone, reducing residual stromal thickness and enhancing biomechanical stability, making it possible to correct eyes with large sight defects that were previously uncorrectable, while promoting rapid healing and minimizing regression.
Implementation Method 1
the excimer laser, which removes, by ablation, the corneal tissue which is exposed under the lamella in this manner
Implementation Method 2
a cutting geometry which separates a cornea volume (known as a lenticule) in the cornea is formed in the cornea of the eye by means of a short-pulse laser, preferably a femtosecond laser
Data Source
AI summary
A planning device produces control data for a treatment device for eye surgery which produces at least one cutting surface in a cornea of the eye using a laser device. The planning device includes a calculation module for establishing a cornea cutting surface. The calculation module is configured to establish the cornea cutting surface based on data of a refraction correction, to produce a control data set for actuating the laser device for the cornea cutting surface, and to determine the cornea cutting surface in such a way that it consists of a plurality of sub-surfaces, each of which make a contribution to the refraction correction.