Ophthalmic Laser Modulator for Corneal Incision Thermal Management
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Solution Overview
Problem
The use of femtosecond lasers in ophthalmic surgery for corneal incisions can lead to thermal damage due to uneven energy distribution along the scan path, particularly at reversing bends where scanner inertia causes local concentrations of laser spots, potentially resulting in thermal damage to the corneal tissue.
Innovation Solution
A system that includes a pulsed laser source, a scanner, an electronic control unit, and a modulator unit to adjust laser pulse energy or suppress pulses in regions of high energy input, ensuring reduced area-specific energy input by modulating or blanking selected laser pulses along the scan path, maintaining consistent pulse repetition rate and spot size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a meandering line scan pattern is used to cut the flap bed, then the incision geometry is achieved, but local concentrations of laser spots occur at reversing bends due to scanner inertia, potentially causing thermal damage
Solution Approach 1:
The patent applies local quality by differentiating pulse energy delivery based on location along the scan path. At reversing bends where scanner inertia causes spot accumulation, the pulse energy is reduced or pulses are suppressed. In linear segments where normal cutting is required, full pulse energy is maintained. This spatially varying energy delivery resolves the contradiction between achieving precise incision geometry and avoiding thermal damage at problematic locations.
Solution Approach 2:
The control unit preemptively identifies reversing bend regions in the scan path and applies energy reduction or pulse suppression before thermal damage can occur. By anticipating the harmful effect of spot accumulation at reversing bends and counteracting it in advance, the system prevents thermal damage while maintaining the overall incision geometry.
2Ease of operation
If constant pulse energy is used along the entire scan path, then the laser system operation is simplified, but area-specific energy input becomes uneven due to path geometry, risking thermal damage
Solution Approach 1:
The patent implements dynamics by making the pulse energy variable rather than constant. The control unit dynamically adjusts pulse energy based on the instantaneous position of the beam focus along the scan path, reducing energy at reversing bends and maintaining full energy in linear segments. This dynamic adaptation resolves the contradiction between operational simplicity and thermal damage prevention.
3Speed
If the scanner operates with inertia at turning-points, then the scan path can be executed, but adjacent focal points become closely spaced, causing excessive local radiation energy
Solution Approach 1:
The control unit uses feedback from the scanner's position and motion state to adjust pulse energy in real-time. By monitoring when the scanner is at reversing bends and reducing pulse energy accordingly, the system compensates for the inertial effects that cause focal point accumulation. This feedback mechanism resolves the contradiction between maintaining scanner speed and controlling local energy deposition.
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 reduces the risk of thermal damage by adapting pulse energy to the ocular tissue based on location and motion patterns, ensuring a non-thermal photodisruption process without compromising incision quality.
Implementation Method 1
the energy density in the beam focus has to be great enough in order to generate an optical breakthrough, the so-called photodisruption
Implementation Method 2
a source of pulsed laser radiation with radiation parameters matched to the making of an incision in an ocular tissue
Data Source
AI summary
The invention relates to a system for ophthalmic laser surgery, comprising a source (110) of pulsed laser radiation with radiation parameters matched to the making of an incision in an ocular tissue, particularly in the cornea, a scanner (160) for deflecting the laser radiation, an electronic control unit (190) which has been set up to control the scanner in accordance with a predetermined incision geometry, and a modulator unit (170) for modulating the laser pulses emitted from the source (110). The control unit (190) has furthermore been set up to control the modulator unit (170) in accordance with a beam-deflection pattern established for the incision geometry in such a manner that in predetermined parts of the beam-deflection pattern at least some of the laser pulses have a reduced pulse energy or are suppressed.