Ophthalmologic Device Asymmetric Pulse Processing
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Solution Overview
Problem
Femtosecond laser systems used for ophthalmological procedures face issues with energy wastage and tissue stress in overlapping areas during cutting operations, leading to unwanted heating and residual tissue bridges.
Innovation Solution
An ophthalmological device with a light projector that generates femtosecond laser pulses with non-circular pulse processing areas, specifically elliptical or oval-shaped, which are aligned to minimize overlapping and reduce energy irradiation, allowing for more efficient cutting with reduced tissue bridges and shorter processing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If circular pulse processing areas are used with conventional focusing, then the focal spots are as circular as possible, but overlapping areas of successive laser pulses cause undesired energy irradiation and tissue bridges
Solution Approach 1:
The patent applies asymmetry by transforming the conventional circular pulse processing areas into non-circular shapes (such as elliptical or kidney-bean shaped). This asymmetric transformation allows the processing areas to be optimized for linear scanning patterns, reducing overlapping regions between successive pulses while maintaining effective tissue dissolution. The asymmetric shape is achieved through specific optical means including cylindrical lenses or astigmatic focusing in the laser projection system.
Solution Approach 2:
The patent implements local quality by creating pulse processing areas with non-uniform intensity distributions and asymmetric geometries tailored to the specific requirements of linear scanning. The intensity profile is optimized locally along the scanning direction to ensure complete tissue dissolution at pulse intervals while minimizing energy deposition in overlapping regions. This local optimization allows different regions of the processing area to serve different functions: the leading edge for primary ablation and the trailing edge for controlled overlap reduction.
2Reliability
If pulse distance is reduced to avoid tissue bridges, then complete tissue dissolution is achieved, but energy wastage increases in overlapping areas
Solution Approach 1:
The asymmetric pulse processing area shape allows for optimized pulse spacing along the linear scanning direction. By elongating the processing area in the scanning direction and compressing it perpendicular to the scan, the system achieves complete tissue dissolution with larger effective pulse separation, reducing the number of overlapping pulses and associated energy wastage while maintaining reliable tissue dissolution without bridges.
Solution Approach 2:
The patent employs dynamic control of the laser scanning parameters and pulse processing area characteristics to optimize the balance between complete tissue dissolution and energy efficiency. The system dynamically adjusts the relationship between pulse repetition frequency, scanning speed, and processing area geometry to minimize overlapping while ensuring complete dissolution, adapting to different tissue types and treatment requirements.
3Ease of operation
If conventional circular pulse processing areas are used, then processing is straightforward, but cutting time increases due to smaller effective cutting track width
Solution Approach 1:
The asymmetric pulse processing areas are specifically designed to elongate in the linear scanning direction, effectively increasing the cutting track width for a given pulse spacing. This geometric transformation allows fewer pulses to cover the same linear distance, reducing total processing time. The asymmetry is achieved through optical means such as cylindrical lenses that focus the laser beam into an elliptical or asymmetric pattern aligned with the scanning direction.
Solution Approach 2:
The patent applies dimensionality change by transforming the isotropic circular pulse processing area into an anisotropic shape with different dimensions along and perpendicular to the scanning direction. This dimensional transformation effectively increases the cutting efficiency by utilizing the scanning direction as a primary dimension for tissue removal, allowing longer processing distances to be covered with the same number of pulses.
4Temperature
If total energy radiated into eye tissue is reduced to minimize heating, then energy wastage in overlapping areas decreases, but processing efficiency may be compromised
Solution Approach 1:
The asymmetric pulse processing area distribution concentrates energy delivery more efficiently along the scanning path, reducing the number of overlapping pulses and associated energy wastage. By optimizing the spatial distribution of pulse processing areas to be asymmetric rather than circular, the system achieves complete tissue dissolution with lower total energy input, minimizing thermal accumulation and heating in the eye tissue while maintaining processing 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
The solution effectively reduces energy wastage and tissue stress by optimizing pulse processing area alignment, resulting in more precise cuts with less energy usage and reduced processing time, while avoiding tissue bridges.
Implementation Method 1
femtosecond laser pulses for the dissolution of eye tissue, the femtosecond laser pulses each being projected onto a focal surface
Implementation Method 2
light projector for projecting femtosecond laser pulses for dissolving eye tissue
Data Source
Figure 1
Figure 2a~2d
Figure 3a~4c
AI summary
Opthalmology device (1) including a light projector (11) for projection of ultrashort femtoseond laser pulses for loosening (disintegration, sic)(Auflosung) of eye tissue (21) with focussing on a focal surface. The device includes an optical agent (13) for production of pulse treatment zones (E) on the focal surface with a zone boundary on this surface deviating from circular profile.