Confocal Measuring System for Corneal Laser Cut Detection
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Solution Overview
Problem
Current ophthalmological laser systems face challenges in accurately performing post-treatment of the cornea due to biomechanical changes after initial laser treatment, making precise follow-up treatments difficult, especially when trying to reuse or reposition existing laser cuts, which can lead to complications and incomplete or incorrect refractive corrections.
Innovation Solution
An ophthalmological laser system equipped with a confocal measuring system, including a beam splitter and control unit, allows for high-accuracy detection and localization of existing laser cuts by using a polarization beam splitter and optical phase delay system to differentiate backscattered light from stray light, enabling precise alignment and post-processing of old cuts for follow-up treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical means (microkeratome) are used to prepare the corneal flap, then the flap can be detached and refractive correction can be performed, but the procedure carries surgical risks and the residual corneal thickness is reduced
Solution Approach 1:
The patent replaces the mechanical microkeratome system with a femtosecond laser system for flap preparation. The laser creates photodisruption in the corneal stroma through optical breakdown, forming a flap without mechanical contact. This substitution eliminates the risks associated with mechanical cutting while preserving corneal thickness better than mechanical methods, as the laser can precisely control the depth and location of incisions.
Solution Approach 2:
The femtosecond laser utilizes optical breakdown and photodisruption - a phase transition phenomenon where the laser radiation creates plasma in the corneal tissue through nonlinear optical absorption. This phase transition from organized tissue structure to plasma state enables precise flap creation without mechanical force, resolving the contradiction between surgical safety and tissue preservation.
2Adaptability or versatility
If follow-up treatment is performed after initial laser treatment, then refractive corrections can be adjusted, but biomechanical changes and epithelial growth make precise repositioning of laser cuts difficult
Solution Approach 1:
The patent performs preliminary mapping and documentation of the initial laser cut positions before biomechanical changes occur. The system records the precise coordinates and characteristics of laser cuts created during the first treatment, storing this data for later reference. This preliminary action enables accurate reproduction or adjustment of cut positions during follow-up treatments, overcoming the problem of position drift due to epithelial growth and corneal remodeling.
Solution Approach 2:
The system incorporates feedback mechanisms where the positions and outcomes of initial laser cuts are detected, measured, and fed back into the treatment planning system. This feedback loop allows the system to compensate for biomechanical changes by adjusting subsequent treatment parameters based on actual measurements of corneal state and previous cut locations, thereby maintaining measurement precision across multiple treatment sessions.
3Device complexity
If a single laser system is used for both flap preparation and refractive correction, then device complexity is reduced, but the laser must be capable of delivering different power levels and pulse durations
Solution Approach 1:
The patent employs a single femtosecond laser system that is designed to perform multiple functions: flap preparation, stromal cutting, and refractive correction. The laser system incorporates variable pulse duration control and adjustable power levels, allowing it to adapt to different surgical requirements. This multi-functional design reduces device complexity by eliminating the need for separate excimer and femtosecond laser systems while maintaining the versatility needed for various refractive procedures.
Solution Approach 2:
The laser system features dynamic parameter adjustment capabilities, where pulse duration, power, and repetition rate can be changed in real-time during different phases of the surgical procedure. This dynamic adaptability allows the same physical laser system to deliver the appropriate parameters for flap creation (higher energy, longer pulses) and precise stromal ablation (lower energy, shorter pulses), resolving the contradiction between device simplicity and functional versatility.
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 solution enables precise reuse or repositioning of old laser cuts, minimizing errors and complications during follow-up treatments by providing high-accuracy imaging and irradiation control, allowing for accurate refractive corrections and reducing the risk of biomechanical changes affecting treatment outcomes.
Implementation Method 1
using a polarization beam splitter and optical phase delay system to differentiate backscattered light from stray light
Implementation Method 2
highly focused radiation from femtosecond lasers has been used to make incisions in the cornea (Femto-LASIK). A photodisruption is generated in the focus, which leads to minimal bubble formation in the stromal tissue.
Implementation Method 3
a laser whose radiation can be focused in an examination area as illumination light via an illumination beam path that has a scanner unit and focusing optics
Data Source
Figure 1
Figure 2A~2B
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AI summary
1. The invention relates to an ophthalmologic laser system and to an operating method. 2.1. Following refractive laser correction to the eye, secondary treatment can be required. The invention enables laser-supported secondary treatment of the cornea with high accuracy. 2.2. In addition to a laser (4) for light, a scanner unit (7) and a focusing lens (8), an ophthalmologic laser system (1) comprises a beam splitter (5) that directs radiation that reaches the beam splitter (5) from the direction of the area of examination through a confocal aperture orifice (11) onto a detector (12), and comprises a control unit with which a cornea (2) arranged in the examination area can be irradiated by means of the laser (4) at a lighting laser power and detection light can be registered by means of the detector (12). The cornea (2) is scanned in three dimensions, in that the cornea is irradiated at multiple points and detection light is registered from there. Based on the detection light, a laser cut (C) in the cornea (2) is identified and the form and/or position of the laser cut (C) calculated. 2.3. The invention further relates to refractive laser surgery.