Laser Corneal Flap Tissue Strip Removal for Creaseless Fit
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Solution Overview
Problem
LASIK treatments for myopia often result in flaps that do not fit perfectly into the corneal bed post-ablation, leading to creases and visual impairments due to the intensive resection of material in the center of the optical zone, which diminishes the radius of curvature and arc length of the optical zone.
Innovation Solution
A device using focused laser radiation with controllable components and a control program to generate incisions in the cornea, including a tissue strip along the peripheral edge of the flap, allowing for targeted shortening of the flap to ensure a snug fit without creases, by defining an incision figure that separates the tissue strip from the flap and corneal bed, facilitating easy removal and optimizing the flap's shape and size based on ablation data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intensive resection of material is performed in the center of the optical zone to correct myopia, then the visual defect is corrected, but the radius of curvature and arc length of the optical zone decrease, causing the flap to not fit perfectly into the corneal bed
Solution Approach 1:
The invention divides the corneal tissue into distinct segments: the flap, the corneal bed, and a connecting tissue strip. This segmentation allows independent manipulation of each part to achieve both effective ablation and precise flap positioning. The tissue strip acts as a separate element that can be removed to adjust flap dimensions.
Solution Approach 2:
The incision figure is predetermined based on the desired ablation profile and flap geometry. The laser creates the complete incision pattern including the tissue strip boundaries before any ablation occurs. This preliminary structuring enables subsequent precise manipulation of the flap to ensure perfect fit after ablation.
2Ease of manufacture
If the flap is folded back after ablation, then the treated cornea is restored, but creases (striae) may form in the flap due to size mismatch, causing visual impairments
Solution Approach 1:
The invention extracts the connecting tissue strip from between the flap and corneal bed. This removal allows the flap to be resized to perfectly match the ablated bed dimensions, eliminating the source of creases and visual impairments while maintaining ease of procedural restoration.
Solution Approach 2:
The invention changes the geometric parameters of the flap by removing the tissue strip, adjusting the flap's arc length and curvature to precisely match the post-ablation bed dimensions. This parameter adjustment prevents mismatch-related crease formation while preserving the restorative function.
3Manufacturing precision
If additional heating and smoothing treatment is applied to the flap after folding, then striae can be eliminated, but the patient undergoes additional treatment burden
Solution Approach 1:
The invention performs the flap sizing adjustment through precise laser incisions and tissue strip removal before the flap is folded back. This preliminary geometric correction eliminates the need for subsequent thermal smoothing, reducing treatment steps while maintaining flap smoothness and precision.
Solution Approach 2:
The invention replaces the thermal/mechanical smoothing process with a precise laser-based geometric adjustment. Instead of heating and mechanically smoothing the flap after folding, the laser precisely removes the tissue strip to achieve the correct dimensions, eliminating the need for additional thermal treatment.
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
The solution prevents the formation of striae by ensuring the flap fits exactly into the corneal bed, reducing the need for additional smoothing measures and minimizing visual impairments, thereby making LASIK operations more patient-friendly.
Implementation Method 1
For the generation of incisions by means of focused laser radiation in transparent material (transparent to the laser radiation), the so-called laser-induced optical breakthrough is utilised by way of physical effect. This results in a photodisruption of the irradiated tissue in the region of the focus.
Implementation Method 2
These exposed tissue regions are then treated in ablating manner by means of focused UV laser radiation, i.e. corneal material is resected in accordance with an ablation profile ascertained individually for the patient.
Data Source
AI summary
A device for machining the human cornea with focused laser radiation includes controllable components for setting the location of the radiation focus, a control computer for controlling these components, and also a control program for the control computer. The control program contains instructions that have been designed to bring about, upon execution by the control computer, the generation of incisions in the cornea in accordance with a predetermined incision figure, the incision figure defining a corneal bed, a flap situated on the bed and also at least one tissue strip situated in the region of the peripheral edge of the flap between the bed and the flap and extending along the edge of the flap. After the flap has been folded away, the tissue strip has to be removed and enables a creaseless post-ablative close fitting of the folded-back flap against the surface of the bed. In this manner, microstriae which may impair the visual capacity can be avoided.