Infrared Laser Parameter Tuning for Low-Heat Tissue Disruption
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Solution Overview
Problem
Existing lasers for tissue disruption, particularly in medical procedures like cataract surgery and vitreoretinal surgery, are inefficient in delivering mechanical disruption while minimizing heat deposition, with efficiencies typically below 0.1 and limited by conventional pulse duration and energy density parameters.
Innovation Solution
Operating lasers at infrared wavelengths between 2.6 to 3.3 microns or 1.8 to 2.1 microns, with pulse durations greater than 1 nanosecond and delivering energy densities of 2,500 J/cm³ or higher, to achieve high efficiency in photodisruption by pressurizing adjacent water volumes and mechanically breaking tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional lasers are used for tissue disruption, then the procedure can be performed, but the disruption efficiency is low (below 0.1) and excessive heat is deposited in adjacent tissue
Solution Approach 1:
The patent changes the laser operating parameters specifically the wavelength (to 2.94 micrometers in the water absorption band) and pulse duration (1-100 nanoseconds) to optimize the balance between disruption efficiency and heat deposition. This parameter optimization enables high disruption efficiency while minimizing thermal damage to surrounding tissue.
Solution Approach 2:
The patent employs pulsed laser operation with specific pulse durations (1-100 nanoseconds) rather than continuous wave operation. This periodic action allows energy delivery in controlled bursts that achieve mechanical disruption through photothermal and photomechanical effects while allowing thermal diffusion to minimize heat accumulation in adjacent tissue between pulses.
2Productivity
If higher pulse energy is used to improve disruption efficiency, then more mechanical disruption is achieved, but heat transfer to adjacent tissue increases
Solution Approach 1:
The patent optimizes the pulse energy parameter within specific ranges (pulse energies from 0.1 to 10 millijoules) combined with specific pulse durations (1-100 nanoseconds) to achieve the desired mechanical disruption while controlling heat transfer. The specific wavelength selection (2.94 micrometers) enhances water absorption to improve mechanical disruption efficiency at lower energies.
Solution Approach 2:
The patent maintains continuous useful action through optimized pulse sequences that deliver energy efficiently for mechanical disruption while allowing sufficient time between pulses for heat dissipation. This continuous optimized action achieves cumulative disruption effect without proportionally increasing heat damage to adjacent tissue.
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 method achieves disruption efficiencies ranging from 0.1 to 0.35, significantly higher than conventional lasers, with minimal heat transfer to adjacent tissue, enabling precise and efficient tissue cutting.
Implementation Method 1
The present disclosure is directed to methods of operating lasers. The lasers may be operated for photodisruption.
Implementation Method 2
The laser energy may be absorbed by a small volume of water that is adjacent to a laser optical fiber tip.
Data Source
AI summary
Methods are disclosed for operating a laser. Such methods may comprise operating the laser to emit electromagnetic energy in an infrared range in pulses with a pulse duration of greater than 1 ns. The wavelength of infrared electromagnetic energy may be in a range of about 2.6μ to about 3.3μ or about 1.8μ to about 2.1μ. The pulses may have a pulse energy selected to deliver an energy density of 2,500 J/cm3 or greater. The laser electromagnetic energy may be delivered for a medical application, such as cataract surgery to break apart a cataractous lens by photodisruption.