Laser apparatus for treatment of a cataractous lens
Inventors
Kraemer, Darren • Cowan, Michael
Assignees
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Publication Number
US-11648150-B2
Publication Date
2023-05-16
Expiration Date
Abstract
An apparatus for aiding the removal of cataracts in which an optical fiber delivers sufficient optical energy of the correct wavelength, pulse duration to achieve controlled non-thermal and non-acoustic dissolution of hard cataract tissue.
Core Innovation
The invention relates to an apparatus for disruption of cataracts in lens tissue enclosed by aqueous humour or vitreous humour using a controllable pulsed mid-infrared laser delivered through an optical waveguide. A source of energy consisting of pulsed laser radiation is controllable to select a pulsing rate, and the optical waveguide transmits the pulsed laser radiation from a proximal end to a distal end located inside the lens tissue via a handle. The pulsed laser radiation is controlled so that the light intensity exiting the optical waveguide produces microdisruption of the lens tissue by impulsive heat deposition.
A central concept is selecting the wavelength to match an absorption peak of at least one component of the lens tissue, with the wavelength in the range of about 2700 nm to about 3300 nm. The wavelength is used to produce laser pulses having energy sufficient that, when absorbed in a volume irradiated by the laser pulses, the irradiated volume reaches superheated temperatures above a vaporization point of the at least one component. The apparatus selects a pulse duration time in the range of about 100 ps to about 10 ns so that each pulse duration time is shorter than a time required for thermal diffusion out of the irradiated volume and shorter than a time required for thermally driven expansion of the irradiated volume to avoid shock wave propagation in the lens tissue.
The invention further limits peak intensity and energy conversion to target microdisruption while avoiding undesirable effects. The combination of selected pulse duration time and selected pulse energy is selected to result in a peak intensity below a threshold for ionization-driven ablation to occur in the irradiated material, and conditions are selected so that conversion of a majority of the energy contained in each laser pulse occurs to ablation of the material in the volume with any residual energy insufficient to substantially damage material surrounding the volume irradiated by the pulsed laser. The apparatus uses tracking of the distal end position through one or more sensors and controller feedback based on the tracked position, with optional refinements described for irrigation/aspiration near the distal end and optical sensing of backscattered light transmitted from near the distal end.
Claims Coverage
The document provides one independent claim. The independent claim defines a microdisruption-based cataract disruption apparatus with controllable pulsed mid-IR laser conditions delivered via an optical waveguide, plus handle-based positional feedback for controlling the distal-end positioning inside aqueous or vitreous humour.
Controllable pulsed mid-IR laser for impulsive heat deposition microdisruption via an optical waveguide
The apparatus includes a source of pulsed laser radiation controllable to select a pulsing rate, and an optical waveguide coupleable to the source to transmit the pulsed laser radiation to the cataracts in enclosed lens tissue, with conditions at the distal end such that the light intensity exiting the optical waveguide is sufficient to produce microdisruption of the lens tissue by impulsive heat deposition.
Wavelength selection to match a lens-tissue absorption peak
The pulsed laser radiation is controlled such that the conditions include a wavelength in the range of about 2700 nm to about 3300 nm, with the wavelength selected to match an absorption peak of at least one component of the lens tissue.
Superheated temperatures above a vaporization point with controlled pulse duration to avoid shockwave propagation
The wavelength causes the pulsed laser radiation to produce laser pulses having energy sufficient to cause, when absorbed in a volume of material irradiated by the laser pulses, superheated temperatures above a vaporization point of the at least one component of material contained in the irradiated volume; and each pulse duration time is selected in the range of about 100 ps to about 10 ns such that each pulse duration time is shorter than a time required for thermal diffusion out of the irradiated volume and shorter than a time required for a thermally driven expansion of the irradiated volume to avoid shock wave propagation in the lens tissue.
Peak intensity and energy conversion selected to avoid ionization-driven ablation and reduce surrounding damage
The combination of selected pulse duration time and selected pulse energy is low enough to result in a peak intensity of each laser pulse below a threshold for ionization-driven ablation to occur in the irradiated material; and the conditions are selected to result in conversion of a majority of the energy contained in each laser pulse to ablation of the material in the irradiated volume with any residual energy being insufficient to substantially damage material surrounding the irradiated volume.
Handle with controller and sensors for tracking distal-end position and feedback control
The apparatus further comprises a handle to insert and control the position of the distal end of the optical waveguide inside the lens tissue, wherein the handle comprises a controller and one or more sensors for tracking a position of the distal end of the optical waveguide inside the lens tissue, and wherein the controller is configured to send signals to the handle to cause the handle to provide a feedback based on the tracked position of the distal end of the optical waveguide.
Overall, the independent claim coverage emphasizes a controllable pulsed laser microdisruption mechanism delivered to cataracts via an optical waveguide, using selected mid-IR wavelength and pulse duration with intensity and energy constraints to avoid ionization-driven ablation and to minimize damage to surrounding tissue, together with handle-based tracking and feedback control of the distal-end position inside lens tissue.
Stated Advantages
Produces microdisruption of the lens tissue by impulsive heat deposition while avoiding shock wave propagation in the lens tissue.
Avoids ionization-driven ablation by selecting peak intensity below a threshold for ionization-driven ablation to occur in the irradiated material.
Converts a majority of the energy contained in each laser pulse to ablation of material in the irradiated volume with any residual energy insufficient to substantially damage material surrounding the irradiated volume.
Uses feedback based on tracked position of the distal end of the optical waveguide inside the lens tissue to control distal-end positioning.
Documented Applications
Disruption of cataracts in lens tissue enclosed by aqueous humour or vitreous humour.
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