Flapless Corneal Reshaping Using Femtosecond Laser Bubbles
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Solution Overview
Problem
Conventional LASIK procedures involve creating a flap, which can lead to complications such as flap striae, epithelial ingrowths, and trauma due to long pulse duration lasers, and there is a need for a method that can reshape the cornea without cutting a flap, while minimizing tissue damage and improving precision.
Innovation Solution
The method involves creating bubbles under the cornea using low-energy femtosecond laser pulses for photo-disruption, followed by channel creation and ablation using multi-photon ablation with higher intensity pulses, allowing for precise reshaping of the cornea without a flap, thereby reducing trauma and improving precision and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long pulse duration lasers (nanosecond) are used for corneal ablation, then tissue can be removed, but strong shock waves and significant tissue heating occur causing trauma and inflammation
Solution Approach 1:
The patent changes the pulse duration parameter from nanosecond scale to femtosecond scale (10^-15 seconds). This parameter change fundamentally alters the interaction mechanism between laser and tissue, enabling photo-disruption at lower energies while minimizing thermal diffusion and shock wave generation, thus resolving the contradiction between ablation efficiency and tissue trauma
Solution Approach 2:
The patent utilizes photo-disruption, a non-thermal ablation process where ultra-short laser pulses cause instantaneous breakdown of molecular bonds in tissue water, creating cavitation bubbles that mechanically remove tissue. This phase transition from thermal to mechanical ablation mechanism eliminates the harmful thermal effects while maintaining productivity
2Productivity
If conventional LASIK flap procedure is performed, then corneal reshaping can be achieved, but complications such as flap striae, epithelial ingrowths, and flap tears occur
Solution Approach 1:
The patent extracts and eliminates the problematic flap creation step from the LASIK procedure. By using femtosecond laser photo-disruption to create channels and reshape the cornea intrastromally without forming a flap, the source of flap-related complications is completely removed while preserving the corneal reshaping function
Solution Approach 2:
The patent replaces the mechanical microkeratome blade used for flap creation with a femtosecond laser system that uses photo-disruption. This substitution eliminates mechanical contact and cutting forces that cause flap complications, achieving flapless corneal reshaping with improved reliability
3Manufacturing precision
If higher intensity laser pulses are used for photo-ablation, then ablation precision improves, but tissue damage and energy loss increase
Solution Approach 1:
The patent uses periodic femtosecond laser pulses delivered at optimized repetition rates. The ultra-short pulse duration ensures that each pulse deposits energy before thermal diffusion can occur, while the periodic delivery allows tissue cooling between pulses. This periodic action maintains high precision while minimizing cumulative energy loss and tissue damage
Solution Approach 2:
The patent achieves continuous corneal reshaping through high repetition rate femtosecond pulsing, where thousands of ultra-short pulses are delivered in rapid succession. This continuous action maintains precision throughout the procedure while the brief intervals between pulses prevent thermal accumulation, optimizing the balance between precision and energy efficiency
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 uniformity of channel creation, decreases the time and energy losses of laser pulses, and improves the precision of stromal ablation, resulting in less tissue damage and faster procedure times.
Implementation Method 1
delivering a first plurality of ultra-short laser pulses 115 to the eye to create at least one row of bubbles 155 in the cornea 110 by photo-disruption
Implementation Method 2
delivering a second plurality of ultra-short laser pulses 190 to the stroma 1025, 1035 to ablate material at the end of the channel 180, 1020 by multi-photon ablation
Data Source
AI summary
Ultra-short pulsed laser radiation is applied to a patient's eye to create a row of bubbles oriented perpendicular to the axis of vision. The row of bubbles leads to a region of the eye to be ablated. In a second step, a femtosecond laser beam guided through the row of bubbles converts it to a channel perpendicular to the axis of vision. In a third step, a femtosecond laser beam is guided through the channel to ablate a portion of the eye. Using a femtosecond laser with intensity in the range of 1011-1015 W/cm2 for the second and third steps facilitates multi-photon ablation that is practically devoid of eye tissue heating. Creating bubbles in the first step increases the speed of channel creation and channel diameter uniformity, thereby increasing the precision of the subsequent multi-photon ablation.